Introduction :
Soaps and Detergents
Soaps
Soap is any salt of a fatty acid, and usually made by saponification of fatty oil with caustic soda. A specific type of salts lowers the surface tension of water and emulsifies fat having soil particles. But now-a-days herbal soaps are preferred by everyone.
Ordinary household bar soap or toilet soap is a mixture of sodium salts of long chain fatty acids. The fatty acids contain 8 to 22 carbon atoms. Potassium ammonium and some organic base like triethoanl amine soaps are, like sodium soap, also soluble in water making a specific type of solution called soap solution. Though the definition of soap covers heavy metalic soaps also, these differ from normal soaps in that they are insoluble in water and therefore do not function in the same manner, i.e. as detergents in water solution.
Soap has a long history of manufacture-from using tallow and wood ashes 2000 years ago to the present-day methods of using oils or fatty acids and caustic soda. Soaps today are far too sophisticated and are available in a wide variety of forms for specific end uses. The twentieth century has seen transformation of soap manufacture from the conventional batch process of boiling oils with caustic soda in kettles to continuous automated processes involving less steam and also higher recovery of glycerine as a by-product. Similarly processes for conversion of soap base to end products such as washing or toilet soaps have undergone a complete transformation.
Laundry soaps were earlier produced as blocks or slabs that were cut into bars and further into cakes. The current process is to spray-cool the molten liquid soap and extrude it as a continuous bar which is cut into billets, stamped and packed.
In the case of toilet soaps, the earlier practice was to dry the soap in a shelf drier, followed by milling, storing the milled chips, mixing with other ingredients in a mixer, milling again and extruding. The cut billets were manually stamped and wrapped. At present, toilet soaps are made through continuous processes. Oils or fatty acids and caustic soda are continuously saponified, spray dried, mixed and extruded. Machines are used to stamp, wrap and pack the soap into cardboard boxes.
There have been changes in formulation also. The import of tallow or other animal fats is banned in India for use in soaps. Practically all indigenous soaps are made from vegetable oils. Tallow is completely replaced by different herbal ingredients.
Synthetic Detergents
The search for substitutes for soaps started during the World Wars because of an acute shortage of oils and fats. Extensive research carried out in Germany and in the U.S. and U.K. eventually led to the adoption of edible oils has widened with the development of methods for pre-treating oils for removing objectionable colours, odours and other harmful compounds and making them suitable for soaps and for the manufacture of fatty acids. Thus, the formulation of oils for soapmaking has undergone a sea change as practically any oils available in commercial quantities can be suitably treated and used for making laundry as well as toilet soaps. This step is also necessary because the import of oils involves an outflow of foreign exchange which is already in short supply.
Linear alkyl benzene is one of the chief raw materials for heavy duty detergents. A number of other heavy duty detergent raw materials have since been marketed each having its own functional benefits. Currently a wide choice of raw materials is available depending on the end use-be it dish washing, for washing ordinary or delicate clothes, or bathing.
Earlier, detergents were made by the organised sector by spray-drying the detergent slurry containing the active ingredient, water-softening chemicals, colour, soil suspending chemical, optical brightener, and other builders that improved detergency. The product was sold as powder packed in moisture-proof cartons. Subsequently, detergents were available in different forms such as cakes and liquids for specific end uses.
More recently detergents containing enzymes and bleaches are available in the form of powders packed in plastic containers. These detergents are more effective in removing proteinaceous stains from the fabrics and in improving overall detergent efficiency.
Physical Properties of Soap
The following properties of pure soap are useful for design engineers and development chemists :
- Viscosity,
- Specific heat,
- Latent heat,
- Density
- The 66% rule,
- Salt distribution between soap curd and lye,
- Glycerol distribution between soap curd and lye, and
- Rate of drying of soap.
Viscosity
When an oil blend is saponified with caustic soda, the resultant soap has a viscosity which is much more than that of either the oil or the caustic soda solution. Above 75oC the viscosity increase is not significant, but below 75oC it increases rapidly.
The viscosity varies in the range of 10-20 Poise depending on the temperature of the soap and the composition of the oil blend. For the purpose of design of pumps, a viscosity of 15 Poise at 80oC may be assumed.
Specific heat
The specific heat of soaps at 0.56 cal/g is satisfactory for calculation of heat transfer rates.
Latent heat
The latent heat of fusion of soaps is approximately 38 cal/g.
Density of soap
The density of pure soap is in the range of 0.96-0.97 g/c.c. at 30oC. It may be noted that the figures quoted for viscosity, density, specific heat and latent heat are used frequently. In actual practice, variations around these figures may be expected depending on the composition of soaps.
66% Rule
A soap curd consists of soap hydrate containing 66% fatty acid and lye, identical in composition to that from which it has separated.
Salt distribution between curd and lye
Applying the 66% rule, the free solution in curd contains the same percentage of salt as the spent lye from which the curd has separated.
Glycerol distribution between curd and lye
The glycerol distribution in curd and lye is related to the water content of the two layers. Thus,
| Water in curd |
Glycerol in curd |
| Water in lye |
Glycerol in lye |
Rate of drying of soap
When soap is allowed to dry by exposure to ambient air, moisture is lost depending on the initial moisture content, its physical structure, duration of exposure, the atmospheric temperature and humidity. Moisture can also be retained or marginally absorbed by the soap when the atmospheric humidity is high.
When soap is dried, the moisture that diffuses from the centre to the surface brings with it some soap and electrolytes which eventually appear as 'bloom' especially if the soap contains fillers such as soda ash and sodium silicate.
Under certain conditions, soaps such as sodium oleate appear on the surface of the soap as hairy growth. This is a phenomenon observed in the case of soaps processed through spray cooling under vacuum, and derived from natural oils and fats which do not contain rosin. This problem can be eliminated by incorporating 1-2% rosin in the oil blend, or by using hydrogenated oil instead of natural hard oils as the hard oil component of the oil blend. It is possible that the elaidic acid in hydrogenated oil is responsible for suppressing the hairy growth on soaps.
Raw Materials Oils and Fats
(The Main Raw Materials for Soaps)
Classification of Fats/Oils
Glycerides of various fatty acids solid at room temperature are called fats and those liquid at room temperature are called oils.
Thus glycerides heaving higher melting points are termed fats and those having lower melting points are termed oils. And these in turn depend upon the nature of fatty acids content of esters. These acids fall in two series as follows.
- Saturated series, such as stearic acid.
- Unsaturated series.
- Mono enoic acid containing one double bond, such as oleic acid.
- Poly enoic acids containing more than one double bonds, such as linoleic, linolenic acids.
The more unsaturated acids give esters with lower melting points and these are the chief constituents of oils. The more saturated acids containing esters are of higher melting points and are chief constituents of fats (Table-2).
These oils are called fixed oils as distinguished from essential oils and petrolium oils. Fixed oils cannot be distilled without some decomposition under normal atmospheric pressure. Only fixed oil produces soap.
Fatty Oils are Further Classified as :
Animal origine : These usually occur as fats, such as tallow, lard etc. The liquid types include fish oils, fish liver oils, sperm oils etc.
Vegetable origin : These are again sub classified as :
A. On the Basis of Degree of Unsaturation
| Drying |
Iodine value above 130 (linseed oil, Tung oil). |
| Semi drying |
Iodine value 90-130 (soyabean oil, cottonseed oil etc.) |
| Non drying |
Iodine value below 90 (coconut oil, castor oil etc.) |
B.Enedible Soap stocks (palm oil, coconut oil, mahua oil, rice bran oil other enedible varieties of vegetable oils).
C. Edible (sunflower oil, coconut oil, corn oil, soyabean oil, mustard oil, olive oil, cotton-seed oil etc.).
Theoretically any oil or fat can be used for making soap. However, in actual practice, the usage of an oil or fat is dictated by the following considerations :
- Suitability
- Availability in commercial quantity
- Price
In India import of animal fat is banned. Therefore, the discussion on raw materials will be mainly confined to vegetable oils and fats. Table 2.1 shows the approximate availability of indigenous oils for soap-making.
Other oils used in small quantities are mango kernel, watermelon seed, tobacco seed, khakan, pilu, nahor, undi, dhupa, jute seed, tea-seed etc. for which reliable statistics are not available.
The suitability of an oil for soap-making depends upon its analytical characteristics and the end use of the soap to be produced. The physical hardness of soap depends on the type of oil used. In order to obtain the right hardness it is common to use a blend of oils for soap-making. This subject will be discussed further in Chapter 3. The usage of an oil is also determined by its price and availability.
Table 2.2 shows the analytical characteristics of common soapmaking oils.
Table 2.1 Availability of oils for Soapmaking (1991-1992)
| Oils | Tonnes* |
| Rice bran |
1,70,000 |
| Sal seed |
30,000 |
| Acid Oils |
1,00,000 |
| Castor |
60,000 |
| Groundnut RGII |
40,000 |
| Coconut |
30,000 |
| Linseed |
30,000 |
| Neem |
20,000 |
| Mowrah |
20,000 |
| Karanja |
20,000 |
| Kusum |
4,000 |
*Average estimate from ISTMA, DGTD.
For a better understanding of the quality of fatty raw materials for soaps, it is necessary to explain the significance of the following characteristics :
- Colour
- Saponification value
- Iodine value
- FFA content
- Titre
- Fatty acids, containing OH and CO groups.
Colour
All oils possess a characteristic colour. Light coloured oils are preferred for making soap. The colour of an oils can be measured quantitatively by using an instrument called tintometer. The colour reading is carried out by matching the colour of the oil taken in a glass cell of definite thickness against standard tinted glass slides and recorded as yellow, red and, if necessary, blue units. The standard instrument used for the purpose is Lovibond tintometer. All contracts for the purchase of oil specify the acceptable colour reading, and the size of the cell (container) in which the oil colour is to be taken. The oil is regraded as inferior if the colour reading is higher than the specified value. There is also a procedure for adding up the yellow, red and blue colours into a composite unit for the sake of convenience. This procedure is stipulated in the contract.
Saponification Value
This is abbreviated as sap value and is defined as the number of milligrams of potassium hydroxide required to fully saponify one gram of oil.
It should be noted that the saponification value of an oil is variable within limits. This is why a range of values is prescribed for each oil. The figure for any particular oil can be determined by standard chemical procedures.
Table 3 : Characteristics of Various Oils and Fats
| Oil/Fat | Saponification value | Iodine value | Titer 0C | Unsaponifiable matter, % |
| Coconut |
250-260 |
7.5-10.5 |
20-24 |
0.2-0.5 |
| Palm karnel |
245-255 |
14-22 |
20-25 |
2-0.8 |
| Babassu kernel |
247-253 12-16 |
22-24 |
02-07 |
| Palm |
195-205 |
44-58 |
40-47 |
0.2-0.8 |
| Tollow (cattle) |
192-198 |
31-47 |
39-52 |
0.2-0.3 |
| Lard |
190-203 |
46-66 |
34-42 |
0.2-0.4 |
| Chinese vegetable tallow |
180-205 |
3-40 |
45-55 |
1-1.5 |
| Grease (fleshing) |
190-195 |
35-40 |
0.8-1.0 |
| Corn |
187-193 |
103-130 |
14-20 |
1.3-2.0 |
| Cottonseed |
189-200 |
103-115 |
32-38 |
0.5-1.5 |
| Groundnut |
188-196 |
84-100 |
26-32 |
0.2-1.0 |
| Castor |
176-185 |
80-90 |
3-5 |
0.3-1.0 |
| Ol Oive |
188-195 |
78-85 |
17-20 |
0.5-1.5 |
| Rice bran |
180-195 |
92-110 |
27-29 |
3-5 |
| MaMahua |
180-190 |
- |
- |
- |
| LiLinseed |
188-195 |
170-205 |
19-21 |
0.5-1.5 |
| Neat's foot |
192-197 |
67-73 |
24-27 |
0.1-0.7 |
| Fish |
180-195 |
125-190 |
23-30 |
0.5-4.0 |
Saponification value is by itself not a test for the identification of oils. It is a value which is used for calculating the requirement of caustic soda for fully saponifying the oil, and it helps in detecting gross adulteration in some cases.
Since saponification value is expressed in terms of caustic potash, it is necessary to apply a factor for conversion to caustic soda, while calculating the theoretical quantity of sodium hydroxide needed for the complete saponification of the oil charge.
Iodine Value
All oils mainly contain glycerides of fatty acids. These fatty acids can be broadly classified as saturated fatty acids e.g. stearic acid, and unsaturated fatty acids e.g. oleic acid. The chemical formulae of these fatty acids can be written as follows :
It can be seen that oleic acid is characterised by the presence of a double bond in its structure. These are other fatty acids with more than one double bond, e.g. linoleic acid has two double bonds and linolenic acid has three double bonds.
In general, oils containing unsaturated fatty acids give rise to soft soap. The greater the unsaturation, softer is the soap. Iodine value is a measure of the extent of unsaturation of oils; higher the iodine value, higher is the unsaturation. It is defined as the percentage of iodine absorbed by the oil. If the molecular weight of the unsaturated fatty acid is known, it is possible to calculate the iodine value of the fatty acid.
Example : Oleic acid having one double bond can absorb two atoms of iodine as shown by the following equation :
The molecular weight (rounded off to the nearest integer) of oleic acid is 282 and that of Iodine is 2 x 127 = 254. Thus 282 gms of oleic acid will absorb 252 gms of iodine. Therefore the iodine value of oleic acid (rounded off to the nearest integer) is(254/282) x 100 = 90.
Similarly, the iodine values of linoleic acid and linolenic acid are 180 and 270 respectively.
Oils contain unsaturated fatty acids in different proportions. Each oil is characterised by its iodine value and if the soap is derived from a blend of oils, the iodine value of the blend is important, as it indicates the consistency of the soap in terms of its hardness.
It has been seen that for soaps, a satisfactory iodine value of the oil blend should be 50-55.
As in the case of saponification value, the iodine value of an oil also shows variability because of minor changes in its fatty acid composition. Thus each oil has a range of iodine values which are given in Table 2.2.
Iodine values of oils are determined by a standard chemical method. Higher iodine values of oil blends lead to poor stability of soap, since the unsaturated fatty acid components become vulnerable to oxidation leading to rancidity.
Free fatty acids
Not all natural oils are pure glycerides. Oil seeds contain certain enzymes which have the property of splitting the oils present in oleaginous material into their fatty acid components.
The free fatty acid formation is fairly rapid in the case of rice bran and mowrah which depends upon the history of the bran and mowrah seeds respectively and the manner of extraction of the oils. The enzyme action starts in the seed and depending upon the age of the seeds and conditions of storage, the free fatty acid content of the freshly produced oil can vary. The enzymatic action is rapid during storage of rice bran. Some activity also occurs in raw unfiltered oils containing moisture.
Thus, all oils when purchased exhibit a free fatty acidity to the extent to which glycerol is not available from the oil for recovery during soap manufacture.
The importance of stipulating free fatty acids (FFA) content of oils is due to the fact that higher the FFA content, lower is the glycerol recovery. Therefore, oils with lower FFA are preferred.
The percentage of free fatty acids is calculated as lauric acid for coconut and palm kernel oils, and as oleic acid for most other oils. The free fatty acids can also be expressed in terms of the acid value, the number of milligrams of potassium hydroxide required to neutralise FFA in 1 gram of oil. The relationship between the acid value and % FFA (calculated as oleic acid) is : 1 unit of acid value = 0.503% FFA.
Titre
Titre represents the setting point of the fatty acids contained in an oil. It is a property that determines the composition of oil charge designed for soaps.
The titre is generally specified as a test for semi-hard and hard oils especially when such oils form the bulk component of the oil blend. Titre is not a test for identification of oils, but provides a tool for the quality control of major hard oil components and oil blends used in soapmaking.
Fatty acids containing-OH and -CO groups, hydroxy and keto-stearic acids
Hydroxy (OH) and keto-stearic acids (CO) are specified only in the case of processed castor oil for soap manufacture. They are related to work-softening of soaps and will be discussed under section 2.1.2.
Characteristics of individual Oils
Oils cannot be used alone in making good quality soaps. Based on the quality requirements of a soap such as its colour, odour, shelf life, etc., it is necessary to pre-treat the oil in order to render it suitable for use. Subsequently, the cost of the treated oil, its availability, and suitability will determine its level of usage in a formulation. In the case of laundry soaps, the level of usage of an oil and pre-treatment needs are more flexible, since the soap is used only for washing clothes. On the other hand, in toilet soaps the level of usage of a each oil and its quality standards are critical. The flexibility can be increased if the oil is split into its fatty acid, distilled, and the distillate used for soapmaking.
The characteristics of some important vegetable oils used in soapmaking are discussed below :
Rice bran oil
Rice bran oil is a very important source of indigenous oil that has a vast potential for use in soaps. The resources are however not fully tapped.
Two grades of the oil are commercially available: the edible grade with low FFA content (under 10%) and the soap grade with FFA content up to 60%.
The oil is dark brown colour and it is difficult to measure its colour in standard instruments such as the Lovibond tintometer. Hence, the colour is normally not specified when purchasing the oil.
When rice bran oil is saponified, it gives soft soap and therefore it is necessary to hydrogenate it to an iodine value of 45 units for use as a hard oil component. Because of the dark colour, it is also necessary to bleach the oil prior to use. Conventional bleaching by using activated bleaching earth is unsatisfactory. Chemical bleaching with sodium chlorate or chlorite in an acidic medium is adequate for use of the oil in laundry soap. The method for chemical bleaching has been described later in this chapter.
For use in toilet soaps, the hydrogenated oil is split under pressure into its fatty acids which are then distilled. The distillate, which has a light colour, is used for making toilet soaps when mixed with other oils and/or fatty acids.
The analytical characteristics of soft as well as hard rice bran oil are shown in Table 2.2. The characteristics of the rice bran fatty acids are somewhat similar except for the colour which is very light and has a pale pinkish tint.
Sal
Sal is a natural hard fat of tree origin found in abundant quantities in the remote forests of West Bengal, Assam, Uttar Pradesh, Madhya Pradesh, Bihar and Orissa. The collection of seeds is however inadequate, thus limiting its availability. The oil is dark coloured and needs to be bleached prior to use. The colour which behaves like chlorophyll in nature is destroyed by chemical bleaching, or by bleaching with a highly active bleaching earth. Even after chemical bleaching, the oil has a dark colour which restricts its usage (10-20%) to coloured toilet soaps.
Table 2.2 gives the characteristics of sal oil from which it is evident that there is no need to hydrogenate the oil for use in soapmaking.
Castor oil
Castor oil differs from the conventional soapmaking oils in that the oil contains glyceride of ricinoleic acid, which has in its chemical structure a hydroxyl group, which confers certain undesirable properties from the point of view of using the oil in soapmaking, e.g. ease of salting out the soap from the saponification mass. It is, therefore, necessary to modify the oil by a process of dehydroxylation. Even after dehydroxyation, the oil gives rise to a soft soap. Therefore, a hydrogenation step is also necessary.
The procedure that is adopted on a commercial scale is, to hydrogenate the oil to an iodine value of less than 5, under controlled conditions to minimise the formation of keto-stearic, conjugated dienoic acid, estolides and elaidic acids. The oil is dehydroxylated using acid activated earth under vacuum. The resultant oil may be termed as castor olein since the bulk of the ricinoleic acid in the oil is converted during the hydrogenationdehydroxylation step to oleic acid. (Refer patent no. 151711 for processing castor oil).
The processed castor oil can be used to the extent of 30-40% in laundry soaps and up to 30% in toilet soaps. However, processed castor oil is more expensive as compared to processed rice bran oil, and hence its usage is generally restricted to toilet soaps.
Table 2.2 gives the typical analytical data on processed castor oil, which shows that the oil contains a small proportion of hydroxy and keto-stearic acids. Uncontrolled levels of these constituents can lead to difficulties in plodding of the soap, since the soap undergoes what may be termed as 'work softening' due to mechanical working in the plodder. Extrusion of bars becomes difficult.
Coconut oil
Coconut oil is an essential component of oils used for making toilet soap. Nowadays it is not generally used in laundry soaps because of its high price. The advantage of coconut oil is that it gives a hard soap of light colour and profuse lather. The level of usage depends on the grade of toilet soap and varies in the range of 6-20%. While a bleaching and deodorisation step is desirable this it not essential unless the oil is used for high grade toilet soaps.
The distilled fatty acids of normal or hydrogenated coconut oil are incorporated into toilet soap as a superfatting agent for producing rich and creamy lather.
The analytical characteristics of coconut oil in Table 2.2. shows that the oil is unique in comparison with the rest of the oils because it has a very low iodine value, high saponification value and a desirable fatty acid composition.
Linseed oil
Linseed oil is mainly used in the paint and linoleum industries. Its usage in soapmaking is limited because it is expensive.
The oil is highly unsaturated and if used without pre-treatment would give soft and sticky soap with poor stability. It is essential to hydrogenate the oil prior to its use in making soap. Hydrogenation has to be carried out selectively so that all the linolenic and most linoleic acids present are converted to oleic/stearic acids. A final deodorisation step is desirable. The level of usage of this oil for making soap will depend on its price, availability, and the processing method of the oil.
Typical characteristics of the processed oil are shown in Table 2.2.
Raw grade II groundnut oil (RG II)
Raw Grade II groundnut oil is permitted by the government to be used in soapmaking since it is not considered satisfactory for edible purposes. The Grade I variety is not permitted for conversion to soap.
The oil is mainly obtained by the solvent extraction of groundnut oil cake. It has a dark colour and gives soft soap. The bleached oil is used as a soft oil component in toilet soap base to the extent of 5-10% mainly for balancing the hardness of the soap. It can also be used as a hard oil after bleaching and hydrogenation.
Table 2.2 shows the typical analytical characteristics of the oil.
Mowrah
Mowrah is a natural hard oil used usually up to 30% of the oil blend for toilet soaps depending on its price and availability. When solvent extracted mowrah can be used in laundry soap, the expeller variety is used for toilet soaps, since the stability of these soaps is adversely affected by solvent extracted oil. The expeller oil is bleached by activated earth, and the filtered oil is deodorised prior to use. Trans-esterification by methanolysis, followed by distillation of methyl ester, is an alternative method for upgrading the oil.
Table 2.2 shows the analytical characteristics of mowrah oil.
Kusum oil
Kusum oil is a natural hard oil and can be used for making laundry soaps, after suitable pre-treatment to destroy the cyano-glucosides present in the oil to the extent of 1.2 to 1.5 %. In the absence of pre-treatment, sodium cyanide is produced on saponification. This leads to pollution and allied problems relating to the quality of glycerol recovered. Unlike conventional oils, kusum oil yields only 4-5% glycerol which is usually discarded.
Pre-treatment involves hydrolysis of the cyano-glucosides, using zinc oxide and sodium bisulphite under pressure, followed by settling and removal of the aqueous layer.
The treated oil contains 50-100 ppm residual cyano-glucosides. The oil is saponified separately, and the lye containing glycerol is discarded after dilution with water. The soap is mixed with other soap bases, forming part of the laundry soap base, and processed into the finished product.
Neem oil
Neem is a natural semi-hard oil. It has a strong and characteristic odour that is not desirable in conventional soaps. Nevertheless, the oil has medicinal activity on the skin. Toilet soaps are produced using 30-40% neem oil in the formulation, after subjecting the oil to a deodorising treatment, and using an appropriate perfume and other additives for masking the base odour. For analytical characteristics of this oil please refer to Table 2.2.
Neem oil can also be used to produce neem fatty acids by splitting the oil in an autoclave, or can be used as such after an alcoholic alkali or by physical refining.
Acid oils
During alkali refining of oils in vanaspati factories, a by-product called soap stock is produced in two stages during pre-refining and post-refining. During post-refining, soap stock is obtained in smaller proportions and has a lower iodine value. The mixture of soap stocks can be used as a component for making laundry soaps.
Alternatively, the soap stocks may be split by boiling with sulphuric acid leading to the production of mixed acid oils. These acid oils are dark coloured, and are used as soft oil components of the oil blend used for making laundry soaps, at levels determined by the grade of soap and composition of the remaining oil blend. Typical analytical characteristics of the acid oil are given in Table 2.2.
Although soap stock is cheaper than acid oil, it is bulky, contains impurities and large quantities of water. Certain impurities are removed during the production of acid oil. Some manufacturers use a bit of both when there is limited capacity for handling all the soap stock that is produced. The increased use of edible oils with high FFA content for producing vanaspati has led to an increase in the production of soap stock. Unless soap stock is converted to acid oil, the production of vanaspati may be hampered for want of space for the storage of soap stock. For this reason the acid oil production line is considered an essential wing in vanaspati factories.
These is no colour specification for acid oils since these are variable in composition and their colours are too dark to be read correctly in ordinary tintometers. Consequently, acid oils are mainly used in the production of laundry soaps where the colour of the finished soap is not critical. The actual level of usage will, of course, depend on the grade of soap aimed at.
Acid oils are also difficult to bleach with conventional bleaching earths. Chemical bleaching with 2-3% sodium chlorite or chlorate on oil has been found more effective, but can only upgrade the oil to the laundry soap grade. Another possibility is de-gumming using phosphoric acid (described in a later section) followed by bleaching using superior quality bleaching earth.
In general, small scale, soap manufacturers use a higher proportion of acid oil in the oil charge than do the organised soap manufacturers, mainly due to price considerations.
One way of upgrading acid oil for use in toilet soaps is by splitting the oil and distilling the mixed fatty acids to produce a light coloured distillate. The distillate can be hydrogenated if necessary and used as a component up to certain limits based on development work.
Karanja Oil
This is an oil with a rather unpleasant smell and dark colour, and has limited usage in good grade soaps. The analytical characteristics given in Table 2.2 show that it is a soft oil. It can thus be used in making soap only after hydrogenation. The oil is difficult to bleach, and finds its application at levels of 5% in oil blends for laundry soaps.
Sometimes, an alcoholic alkali refining method is followed for the pre-treatment of karanja oil.
Raw Materials : Herbal Products
This chapter lists and describes the most important herbal products including essential oils used in the manufacture of herbal soaps, shampoos and detergents. To help you, we have grouped together that are related by genus or by association. The plant name appears alphabetically in a bold heading followed by botanical name in italics. Historical and anecdotal information is followed by the individual headings described below with its medicinal properties.
ACACIA ARABICA
A. indica Benth
(N.O. - Mimosaceae)
Sankrit : Babbula
Hindi : Babul
Parts Used : Bark, gum, leaves, seeds, pods.
Historical Aspects : It is used traditionally in ayurveda for a number of afflictions. The bark, which is markedly astringent, was considered a remedy in diarrhoea, dysentery, and as a mouthwash and gargle in aphthous stomatitis, in a decoction. The gum is a powerful demulcent and relieves irritation in infections of the throat and larynx. The twig is commonly used for brushing the teeth.
Botanical Description : A small tree with straight sharp pointed spikes, occurring in pairs beneath the petioles. Leaves: 6-12 pinnae and 20-40 leaflets. Flowers : In rounded heads, axillary, supported upon short peduncles, with bracts above the middle. Pods : Stalked, straight, subindehiscent, persistently grey, with fissures between the 8-12 seeds.
Phytochemistry : It has been studied extensively. Bark : Phenolic constituents and tannins, quercetin, catechin, gallic acid, catechol, epicatechol, dicatechol, epigallocatechin. Leaves contain tannins, carotene, and vitamin C. Pods have 41% tannins. Gum contains polysaccharides, calcium, magnesium, salts of arabic acid, malic acid, L-arabinose, D-galactose, L-rhamnose, oxidative enzymes.
Pharmacology : Alcoholic extract of bark has an antiprotozoal action against E. histolytica. CNS depressant activity was present as seen by amphetamine hyperactivity test. Bark tannins killed bacterial virus (E-coli R host cell) at 1:25,000 dilution within 5 minutes.
Clinical Usage : The juice of tender leaves is used as a lotion in conjunctivitis, while a leaf paste in cold water is used as an anti-dysenteric agent. The root powder is used in leucorrhoea. The bark is used widely as a demulcent, in conjunctivitis, and the gum as an anti-pyretic, and anti-diarrhoeal medicine. The bark extracts are used in medicinal sops.
ACALYPHA INDICA
(N.O. - Euphorbiaceae)
Sans.-Arittmanjarie. Eng.-Indian acalypha. Hind. - Kuppu; Khokali, Ben.-Muktajhuri; Sveta-basanta., Guj.- Vanchi Kanto. Mab.- Khokli; Khajoti. Tel.-Kuppichettu; Harita-manjiri; Kuppinta or Muripindi. Tam.-Kuppivaeni; Kuppaimeni. Can.-Kuppigida. Mal.-Kuppamani. Kon.-Kunkmiphal. Uriya-Indramaris. Sinb.-Kupa-menya.
Habitat: Common annual shrub in Indian gardens and waste places throughout the plains of India.
Parts Used: Leaves, root, stalks (young shoots) and flowers.
Constituents: Alkaloids "acalypus" and "acalyphine."
Action : Cathartic, anthelmintic, expectorant, emetic, anodyne and hypnotic.
Preparations : Infusion of root, powder, decoction, cataplasm, succus (juice expressed), tincture and liquid extract.
Uses : Leaves possess laxative properties; "are used as a substitute for Senega," are used in the form of powder or decoction; mixed with gralic they are used as anthelmintic in worms. Mixed with common salt they are applied to scabies; and their juice mixed which oil forms an application in rheumatic arthritis. Expressed juice of the leaves is a safe, certain and speedy emetic for children in one teaspoonful (1 drachm) doses, in cases of croup; in smaller doses it is expectorant, and is useful in chronic bronchitis, asthma and consumption. The decoction is employed in ear-ache as instillation and also as fomentation round the aching ear; and a cataplasm of the bruised leaves is applied to syphilitic ulcers, to maggot-eaten sores and also to relieve the pain of snake-bites. "Juice from fresh leaves may be employed in scabies and other skin diseases, and with lime and onion it is a good stimulating application in rheumatism." Powder of dry leaves is used in bed sores. In congestive headache a piece of cotton saturated with the expressed juice of the plant or leaves and inserted into each nostril is said to relieve it by causing haemorrhage from the nose. In cases of obstinate constipation of children the leaves ground into a paste and made into a ball and introduced into the rectum, relaxes the sphincter ani and produces free motions. An infusion of the root or the root bruised in water, acts as a cathartic. In the treatment of acute mania the following is recommended.-Macerate three ounces of the fresh leaves, stalks and flowers in a pint of spirit of wine in a closed jar for seven days, occasionally agitating the same, strain, press, filter and add sufficient spirits of either to make one pint; dose is from 30 to 60 minims frequently repeated during the day in honey. Hakims treat cases of acute mania and hysteria in early stages by the following mode :-Take one ounce of fresh juice of the leaves and dissolve in it six grains of common salt; drop a little of this mixture in each nostril every six hours from morning and then place the patient under cold shower baths for three mornings regularly; this causes a quantity of mucus and other matter to escape from the nostrils.
The juice gives cooling effect to skin diseases and is extensively used in herbal soap solution.
ANDROPOGON MURICATUS. Retz. or A. Squarrosus.
(N.O. - Gramineae)
Sans. Usheera; Veeranam; Amranalam. Eng. Cuscus grass. Hind. Khas; Khas bena. Ben. Khaskhas. Guj. Valo. Mah. Vala. Gwalior. Khus. Tel. Kuruvaeru; Vetti-vellu; Vetti-veru. Tam. Vettiver. Mal. Ramachham. Can. Lavanchi; Mudivala. Kon. Bhanavalo. Punj. Panni.
Habitat - Coromandel Coast, Mysore, Bengal, Rajputana, and Chota Nagpur.
Parts Used - Fibrous wiry roots from the rhizome.
Constituents - A volatile essential oil, resin, colouring matter, a free acid, a salt of lime, oxide of iron and woody matters.
Action : Tonic, refrigerant, stomachic, stimulant, anti-spasmodic, disphoretic, diuretic and emmenagogue.
Action and Uses in Ayurveda and Siddha - Tikta rasam, Mathura anurasam, seetha-veeryam, kapha pitta-haram, lago, pachanam, sthambhanam, in jwaram, chardhi, trishna, rakta dosham, visarpam, daham, krichram, vranam.
Action and Uses in Unani - Hot 20, Dry 20. Tonic to heart and brain, bood-purifier, headache, palpitation."
Preparations - Powder, dose - 5 to 30 grains; infusion (1 in 40), dose - 1 to ounces; paste for external application. Essence or oil or otto, dose : 1 to 2 minims on loaf sugar.
Uses : Being a cooling medicine it is in the form of infusion a grateful refreshing drink in fevers, inflammations and irritability of the stomach. Externally a paste of root is rubbed on the skin to remove oppressive heat or burning of the body. By mixing it with red sandalwood and a fragrant wood called padma kasta (all in powder) to a tub of water an aromatic bath is prepared. Its essence or oil or otto is given in two minim doses to check the vomitting of cholera, and it used in perfumery. Grass used in the form of cigarettes and smoked with benzoin relieves headache.
Angelica (Angelica archangelica)
Thought to have originated in Syria, angelica was one of the few aromatics exported to the Orient. The oil was a common flavoring and apothecary drug, and magical powers were attributed to it as the "root of the Holy Ghost." The way angelica hovers over the herb garden, it's no wonder! It offers little fragrance until you bite into a seed or snap a root. It still flavors Cointreau liqueur.
Family : Apiaceae (Umbelliferae)
Extraction : Distilled from root or seed. Absolute. The root oil is stronger and slightly more expensive, and it smells earth/herbal; the seed oil is spicy/peppery.
Medicinal Action : Angelica regulates menstruation, is a digestive tonic and stops coughing.
Emotional Attribute : The fragrance relieves depression (especially nerve-related) and provides a new outlook on problems.
Considerations : Use angelica very carefully : it can overstimulate the nervous system, and the root oil contains photosensitizing bergaptene.
Anise (Pimpinella anisum)
Originally form Asia Minor and Egypt, anise now grows throughout the Mediterranean. Turner's 1551 Herbal recommends it "maketh the breth sweater." The oil's delightful taste still flavors pharmaceuticals, confections, toothpaste, "licorice" candy in the United States, and numerous alcoholic beverages around the world such as French anisette, Turkish raki, Latin American aguardiente, Latvian kummel, Spanish ojen and Greek ouzo.
Family : Apiaceae (Umbelliferae)
Extraction : Distilled from the seed, anise has a sweet, licoricelike scent. The oil solidifies at room temperatures.
Medicinal Action : Anise is calming, and it reduces muscle spasms, indigestion and coughing. It is also mildly hormonal, increasing breast milk.
Emotional Attribute : Smelling anise enhances relaxation, sleep patterns, emotional balance and even a sense of humor. It relieves stress from over-work. Said to be aphrodisiac, anise overcomes heartache.
Considerations : The oil can be narcotic and can slow circulation, so be careful. Although it may not be detrimental, it should be avoided by those with problems related to high estrogen. The anethole found in anise causes skin dermatitis in sensitive individuals.
Associated Oil
Star Anise (Illicium verum)-This Oriental tree oil has similar chemistry and scent, so it sometimes replaces anise. It is distilled mostly from seed and occasionally from the star shaped fruit. The related I. religiosum was once combined with rue and pyrethrum as a fumigant to keep bugs out of books.
AZADIRACHTA INDICA.
(N.O. Meliaceae)
Sans. - Raevipriya; Vembaka; Vranashodhakari; Nimba; Arishta; Pichumanthah. Eng. - Neem or Margosa Tree; Indian Lilac. Fr. - Azadirae d'Inde; Margousier. Ger. - Indischer Zedrach. Hind., Duk., Punj. & Ben. - Nim or Nimb; Nimga-chh. Guj. - Limba. Mah. - Kadunimba. Bom. - Nim; Balanimb; Tel. - Vepa. Tam. - Vembu; Veppan. Mal. - Veepan. Can. - Bevina-mara; Kahibevu. Kon. - Beva-rooku. Pers. - Neem. Sinh. - Kohumba. Burm. - Tamabin; Kamabin Malay - Dawon Nambu; Baypay.
Habitat - Indigenous to and cultivated nearly all over India and in Burma.
Parts Used - Every part of the plant - bark, root-bark, young fruit, nut or seed, flowers, leaves, gum and toddy or sap. "Bark and leaves are of particular interest from medicinal point of view."
Constituents - "The bark exudes a clean bright amber-coloured gum which is collected in small tears or fragments. It contains a bitter alkaloid named 'margosine' in long white needles, as a double salt of margosine and soda-a neutral, amorphous resin believed to reside in the inner bark or liber. Leaves contain a small quantity of bitter substance of a similar character but much more soluble in water. This substance also contained in the bark is a hydrate of the resin which it closely resembles in its properties. Seeds contain about 10 to 31 p.c. of a yellow bitter fixed oil which is extracted by boiling or by pressure. "The oil is deep yellow in colour and has a strongly disagreeable acid taste; it has a specific gravity of 0.9235 at 15.50C; at about 100 to 70C, if congealed without losing its transparency; the oil contained free and volatile fatty acids. After standing for about 36 hours, the freshly expressed oil deposited a white sediment which on microscopical examination was found to be amorphous in character. The colour reactions of the margosa oil were not characteristic. The volatile fatty acids probably consist of mixture of stearic and oleic acids with a small amount of lauric acid.
The oil contains following constituents : (1) Sulphur 0.427 per cent; (2) a very bitter yellowish substance obtained from the alcoholic extract of the oil, which is supposed to be an alkaloid; (3) Resins; (4) Glucosides, indifinite; (5) Fatty acids.
We had also prepared an acid named 'Margosic acid' and its salts from the neem oil. had also been prepared (The process is decribed in Chopra's "Indigenous Drugs of India"). The salts are nearly white in colour and are soluble in water. They are extremely bitter to taste.
Some consider that the objectionable odour of the neem oil is chiefly due to organic sulphur compounds which are slightly volatile. On prolonged steam distillation of the oil a volatile sulphur compound slowly distils over and collects on the condensed water. A bitter principle, about 200 times as bitter as the original oil, was separated by these workers. The ultimate analysis of the bitter substance showed that it consists of two different portions-an amorphous and a crystalline substance. The crystalline substance has been termed "margosopicrin."
However, some consider that the odorous element in the oil consists of an evil-smelling essential oil which remains in a state of solution of the oil itself and cannot be easily separated on distillation.
It was shown that the bitterness of the oil is due to the presence of the sodium salt of an acid and partly to the presence of the free acid which are held in solution in the oil. The acid contains sulphur in its molecule and is unsaturated."
The toddy or sap contains glucose, sucrose, gums and colouring matter, proteids and ash, containing potassium, iron, aluminium, calcium and carbon dioxide. Neem oil contains margosic acid, glycerides of fatty acids (soluble 3.5 p.c., insoluble 89.1 p.c.), butyric acid and a trace of valeric acid detected as volatile acids, a small quantity of neutral resin, two other acid resins and a small quantity of an alkaloidal substance. Cake left after expression of oil was found to contain a neutral principle, organic matter 83 to 84 p.c., moisture, and ash 6 to 9 p.c. containing nitrogen and phosphoric anhydride.
Action : Root-bark and young fruit are astringent, tonic and antiperiodic. Bark is bitter, tonic, astringent, anti-periodic and also vermifuge. Fruit is purgative, emollient and anthelmintic. Leaves are discutient; leaf juice is anthelmintic. Oil from nuts and leaves is local stimulant, insecticide and antiseptic. Flowers are stimulant, tonic and stomachic. Gum form the bark is a stimulant and demulcent tonic. Toddy is refrigerant, nutrient and alterative tonic. The drug also possesses antispiroc aetal and emmenagogue properties.
Most of the ingredients of herbal soaps are cooked in Neem oil.
Basil (Ocimum basilicum)
Basil comes from India, but has been cultivated in the Mediterranean for thousands of years and is now also grown in North Africa. The genus name Ocimum is probably from the Greek word "to smell." Once made into cleansing water for the hands and feet, it provides modern perfumes and soaps with an inexpensive substitute for mignonette (lily of the valley). The basils are so diverse in their scents, it has been suggested that they be classified according to chemistry instead of botany. You need to grow your own to have a complete collection, since only a few types are distilled. We have fun home-distilling a variety of spicy, citrus and fruity basils into hydrosols.
Family : Lamiaceae (Labiatae)
Extraction : Distilled from the leaf and flowering tops. The scent is sweet and spicy.
Medicinal Action : The scent relieves headaches, sinus congestion, head colds and resulting loss of smell. Basil treats herpes, shingles, nausea (even from chemotherapy), indigestion and sore muscles. Basil hormonally stimulates adrenals, menstruation, childbirth and production of breast milk.
Cosmetic/Skin Use : Used for oily skin conditions.
Emotional Attribute : Basil's uplifting effect overcomes a lack of confidence, indecisiveness, negative thoughts, stress, rattled nerves, hysteria and mental fatigue. It is said to increase awareness of one's surroundings. Gerard found the buoyant smell "good for the heart" and said it "taketh away sorrowfulness."
Considerations : Large dosages can be overstimulating and may eventually stupefy.
Associated Oils : Reunion Basil (O. basilicum)- This variation from the Comoro and Reunion Islands (hence its name) has a harsher, more herbal scent. It flavours food and dental products. It contains very little linalol, but has 70-88 percent methyl chavicol, a skin irritant, so use carefully.
Eest Indian Basil (O. gratissimum) : Chemotypes of this East Indian species supply high percentages of thymol or eugenol. Hairy Basil (O. Canum) : From East Africa, this basil is delightfully spicy because of its high content of methyl cinnamate and camphor.
BALSAMODENDRON MUKUL, HOOK. or B. agollocha.
(N.O. - Burseraceae)
Sans. - Guggula; Kou-shikaha. Eng. - Salaitree; Gum-gugul; Indian Bedellium. Hind., Duk., Tel., & Mah. - Gugal. Ben. Guggul; Mukul Can. Guggula. Tam - Gukkulu; Gukkal; Mastsatchi Kungiliyam. Tel - Maihakshi, Gukkulu. Guj - Gugara; Gugal. Arab. - Mogla; Mool; Mokhil; Aphalatana. Pers. - Baijahundana. Sinh. - Rata-dummula.
Habitat - Sind, Rajputana, Eastern Bengal, Berars, Assam, Khandesh and Mysore.
Characteristics - When fresh the oleo-gum-resin is moist, viscid, fragrant and of a golden colour. It burns in fire, melts in the sun, and forms a milky emulsion with hot water.
Parts Used - Gum
Constituents - Volatile oil, gum-resin and bitter principle.
Action - Demulcent, aperient, alterative, carminative, anti- spasmodic and emmenagogue. "The pharmcological action of the olco-resin resembles in many ways the action of copaiba and cubels. It has no action on the unbroken skin, but on the abraded skin and on the mucous membranes, it acts as an astringent and antispetic. When taken internally it acts as a bitter, stomachic and carminative, stimulating the appetite and improving the digestion. It produces a sensation of warmth in the stomach and is quickly absorbed. Like all oleo-resins it causes an increase of leucocytes in the blood and stimulates phagocytosis. It is excreted by the skin, mucous membranes and the kidneys.
The gum is mixed with sulphur, catechu and borax for the treatment of gonorrhoea, dropsy, foul ulcers and syphilis etc. The gum cooked in coconut oil/Neem oil are used in the manufacture of medicated ayurvedic soaps and detergents.
BALSAMODENDRON MYRRHA (N.O. Burseraceae)
Sanskrit : Vola, Rasagandha
Hindi: Bol, Bal.
Parts Used : Gum from the bark of the tree
Historical Aspects : Myrrh of commerce is obtained from the resinous exudation of the tree B. myrrha. There are at least three varieties, two of them being known as Karam and Mutiya. It is a rare and costly products, very often adulterated with gum of commiphora mukul which is known as false myrrh.
Habitat : Indigenous to North Eastern Africa. Collected in Southern Arabia, Abyssinia, Persia, Siam and sold in Indian bazars.
Botanical Description : A small tree or low bush about 3 m in height with a large trunk, many knotty irregular branches, terminating at right angles in sharp spines. Leaves trifoliate, fruit long and pyriform. Gum resin is obtained from phloem which contains ducts and cavities.
Pharmacognosy : The phloem contains schizogenous ducts and lysigenous cavities which are filled with yellowish granular resinous liquid. With incisions in the bark, the liquid exudes out and hardens to a reddish brown mass. The gum resin is collected from spontaneous exudation from cracks or fissures on the bark. Myrrh occurs in irregular agglutinated tears or masses. Its external surface is rough and reddish brown, covered with yellowish dust. Thin pieces are translucent or almost transparent, odour is aromatic and taste aromatic, bitter and acrid.
Phytochemistry : Myrrh contains volatile oil 2 to 10%, resin 25 to 40% and gum 57 to 61% and 3 to 4% impurities. Volatile oil is called as myrrhol and contains cuminicaldehyde, eugenol, m-cresol, pinene, limonene, dipentene and two sesquiterpenes.
Ayurvedic Properties : Guna : Ruksha, Laghu. Rasa : Katu, Tikta, Kashaya, Veerya : Ushna. Vipaka : Katu. Dosha : Tridoshahara. Karma : Pradarahara.
Pharmacology : Volatile oil of myrrh exhibits anti-fungal activity against Rhizopus nigricans, Saccharomyces cerviseae, Fusarium oxysporum and Gibberella funtukaros. X-ray irradiation causes only slight increase in anti-fungal activity.
Clinical Usage : Myrrh has stimulant and antiseptic properties and is mainly used in medicinal tooth powder and mouth wash and soap. Useful in dyspepsia, it is also given in menstrual disorders and as a stimulating expectorant in chest diseases, especially in chronic bronchitis and asthma. Externally it is used as an astringent, also for stimulating healing in ulcerated conditions and as a gargle for spongy gums and in ulcerated sore throat. It is used to prevent hair loss. Tincture of myrrh is useful in menstrual disorders and chlorosis in young girls.
Bay (Laurus nobilis)
Also called "laurel" bay leaves were once placed on the heads of headache sufferers and Greek scholars. Today, we still confer a baccalaureate degree, which means "noble berry tree" in French. Crush a leaf and the smell is so intense it can produce a headache as easily as cure one. Apparently bay has even more interesting properties : the ancient Greek priestesses at Delphi sat over the burning fumes to increase their prophetic visions.
Family : Lauraceae
Extraction : Distilled from leaf (occasionally berry). Smells pungent and spicy.
Medicinal action : Bay is a stimulant to lymph, sinuses lungs, and circulation. It makes a very good liniment.
Emotional Attribute : Smelling bay is stimulating and is said to improve memory.
Associated Oils :
Bay Rum Tree (Pimenta racemosa) : Also called "oil of pimento," this is the source of most commercial bay oil and the scent in Bay Rum cologne, which was originally from the Virgin Islands and made with rum. Cooler and sweeter than true bay, it scents bay soaps, cosmetics and colognes.
Allspice (P. dioica) : Familiar to cooks, this culinary seed tastes like a combination of cloves, cinnamon and pepper. It is the source of pimento water, an indigestion remedy in the West Indies and South America, where this evergreen grows. The name comes from the Spanish pimiento because the seed (actually a berry) looks like black pepper. It is old as "Bay" oil.
Benzoin (Styrax benzoin)
The Arabs, who traded it for a frankincense substitute, called this Southeast Asia tree "incense of Java," or luban jawi. The Europeans interpreted this as benjawi and pronounced it "benjamin," then "benzoin." They made solid "vanilla" pomades from it. In India, the fragrance is sacred to the Brahma-Shiva-Vishnu triad, and Malays use it to deter devils during rice-harvesting ceremonies. The sweeter Sumatran S. tonkinense, especially the thick "almond tears," is considered better quality than the Sumatran S. benzoin.
Family : Styracaceae
Extraction : Solvent extracted from gum resin. Absolute, often thinned with ethyl glycol. It has a sweet, vanilla-like odor.
Medicinal Action : Once called "friar's balsam" because it soothes coughs and relieves lung congestion, a formula is still sold by this name. It is also used to treat poor circulation and muscular problems.
Cosmetic/Skin Use : Benzoin is antiseptic, anti-fungal, protects chapped skin and increases skin elasticity. Emotional Attribute : This fragrance is for those who feel anxious, emotionally blocked, lonely or exhausted, especially from a life crisis. It creates a "safe space" that protects one from outside interference.
Considerations : Skin sensitizing.
Associated Oils :
Balsam of Tolu (Myroxylon balsamum) : A Colombian tree once cultivated by the Incas for its vanilla-like fragrance and medicine. The oil, distilled from the gum resin, treats lung congestion, scabies, eczema, and ringworm. Skin sensitizing.
Balsam of Peru (M. balsamum var. Pereirae) : This El Salvadoran tree got its name because it was shipped with Peruvian goods. The taste is hotter and more bitter than tolu. Skin sensitizing.
Styrax (Liquidamber orientalis) : The vanilla-like resin from this tree is used for indigestion, intestinal worms, poor appetite (especially due to illness), insomnia and menstrual irregularity. It can be toxic in quantity. L. styraciflua is the American variety. Skin sensitizing.
Bergamot (Citrus bergamia)
The small green fruit produced by this Mediterranean citrus tree aren't edible or pretty, but the smell they emit is wonderful! Unfortunately, you must live in a warm climate like California to grow them. First mentioned in the 17th century En la Parfumerie Francoise, the fruit was named after Bergamo, Italy, where the oil originated. It is still grown in Italy, mostly in Calabria. Bergamot scents many colognes and flavors Earl Grey tea and some candies. Don't confuse this citrus with the common herb-garden bee balm (Monarda didyma), also called bergamot.
Family : Rutaceae.
Extraction : Cold-pressed from almost-ripe fruit rind. Fresh, clean scent.
Medicinal Action : An anti-inflammatory and antiseptic, bergamot enhances immunity; treats genital, urinary, mouth and throat infections, flu, herpes, shingles and chicken pox; and aids digestion. It is a traditional Italian folk medicine for fever and intestinal worms.
Cosmetic/Skin Use : Bergapten-free bergamot is suitable on most skin conditions and eczema, and is a deodorizer.
Emotional Attribute : Sniff bergamot to reduce depression, anxiety, insomnia or compulsive behavior cycles (including eating disorders). It balances emotions, instilling composure.
Considerations : Because it contains bergapten, bergamot is photosensitizing (i.e. may cause a reaction when skin is exposed to the sun). A bergapten-free essential oil is available.
Associated Oils : See Lemon, Orange and Orange Blossom.
Birch (Betula lenta)
This North American tree is the common source of Wintergreen oil, with which it shares similar chemistry, properties and fragrance. The formula for the popular 19th-century "Russian Leather" men's fragrance (so named because it kept book bindings soft) was closely guarded, but we now know it was mostly birch oil.
Family : Betulaceae.
Extraction : Distilled from the inner bark after maceration in warm water. Sweet, sharp scent like some candies.
Medicinal Action : Birch is a muscular and arthritic pain reliever, a diuretic and a circulatory stimulant.
Cosmetic/Skin Use : Birch is a skin softener that soothes irritation and psoriasis and helps prevent dandruff.
Considerations : Use this slightly toxic oil carefully and, because it smell like candy, be sure to store it safely away from children.
Associated Oils :
Birch Tar Oil : The thick tar is produced from the destructive distillation of bark, which involves burning and steam distillation, and produces a smoky odor. It is used on skin infections and infestations.
White Birch (B. alba) : This Northern European oil has different, less toxic, chemistry with similar properties.
Wintergreen (Gaultheria procumbens) : Native to northeastern North America, but a small and not very abundant tree, true wintergreen oil is rarely available and potentially toxic in large doses.
Calendula (Calendula Officinalis)
The oil is costly and almost never available commercially, so we plant the colorful flowers in our gardens and infuse them into an herbal oil to use as a base for essential oils. Since two different flowers are called marigold, calendula is often confused with Tagetes (see Associated Oils, below), the oil of which is more common and also more toxic. Essential oil from both plants is often sold as "calendula".
Family : Asteraceae (Compositae).
Extraction : Absolute or CO2 extraction from flowers. It has a pungent, fragrant odor.
Medicinal Action : Calendula relieves lymphatic congestion, inflammation and hemorrhoids, and is antiseptic.
Cosmetic/Skin Use : Calendula heals skin wounds, rashes, inflammation and bites. Use it on oily complexions.
Associated Oil :
Marigold (Tagetes minuta and T. patuh) : This marigold is sometimes used on calluses, but the tagetone it contains makes the oil toxic and irritating, and the oil is phototoxic. Use calendula instead. Tagetes is high in beta-carotene (the precurser to vitamin A), is deep orange and sometimes sold as "carrot oil." It has recently become popular as an ingredient in perfumes. Use with caution.
Caraway (Carum carvi)
A medieval European love potion, facial water and cordial called Huile de Venus, this "oil of love" toned muscles and softened complexions. It was also sipped to quell indigestion. Today caraway seeds are more likely to find their way into rye bread than facial products.
Family: Apiaceae (Umbelliferae)
Extraction: Distilled from the seed, the fragrance is sharp and somewhat bitter.
Medicinal Action: Caraway relieves indigestion, colds, poor circulation, dizziness, some intestinal parasites, and nerve pain such as toothache.
Cosmetic/Skin Use: A skin softener, caraway improves the complexion and decreases bruising.
Emotional Attribute: The fragrance helps overcome mental strain and improves energy efficiency.
Considerations: Skin irritant.
Cardamom (Elettaria cardamomum)
Cardamom is a relative of ginger from the Middle and Far East, where it flavors Turkish coffee and East Indian chai tea. The seeds were a valued export item in ancient Greece.
Family: Zingiberaceae
Extraction: Distilled from the seed. Oleoresin. The best quality is sweet and spicy. Inferior seeds are more harsh, with a hint of eucalyptus odor.
Medicinal Action: Cardamom treats indigestion, poor appetite, diarrhoea, coughs and muscular spasms.
Emotional Attribute: An invigorating scent which East Indians have long considered an aphrodisiac.
Associated Oil: See Ginger.
CITRUS MEDICA, Linm.
(N.O.-Rutaceae)
Sans.-Karuna ; Mahalunga ; Matulang. Eng. -Citron. Hind-Maphal. Ben.-Chholongo nebu. Mah.-Kagdi limbu ; Mahalung. Punj.-Bajauri-nimbu. Guj.-Balank ; Bijoura ; Turanj. Can.-Madalada-hannu. Tel.-Madeephalamu. Mal.-Madalanarakam. Kon.-Mavalinga.
Habitat.-It is a garden plant chiefly cultivated for its valuable fruit and met with chiefly in Khasia Hills, the south-west of India, and parts of Northern India.
Parts Used-Rind, Juice and oil.
Constituents.-Similar to C. bergamia or C. acida. Oil is obtained from the rind by distillation and by expression. Expressed oil is pale-yellow, fragrant, aromatic, bitter, soluble in alcohol in 3. It contains citrene or limonene 7-6 p. c., citrol 7-8 p. c., cymene and citronellal. Dose : -½ to 3 minims.
Action.-Fruit is an expellant of poisons. Yellow pulp is an excellent aromatic and stomachic. Pulp is bitter and described as cold and dry if acid, but cold and moist if sweet. Rind is aromatic, stimulant, hot, dry and tonic, and is an anti-scorbutic. Distilled water of the fruit is sedative. Seeds, leaves and flowers are hot and dry. Juice is refrigerant, astringent and digestive.
Uses.-Its juice makes a pleasant refrigerant drink (sherbet in allaying febrile heat and thirst, and checks bilious vomiting. It is useful in bilious and remittent fevers when combined with Port Wine and cinchona barn. Thick and fleshy inner rind is made into an excellent marmalade and the pleasant preserve in sugar or honey is used in dysentery. Both fruit and preserve are somewhat bitter to the taste. Candied citron rind is well-known. It is also made into a pickle with salt, sweet oil, chillies and other ingredients, which is useful as an appetiser in various kinds of fever, dyspepsia and inflammatory affections. Rind if steeped in a vessel of wine will convert it into vinegar. Extract of cidrat is the oil of citron dissolved in spirits to which bergamot is sometimes added. Essential oil extracted by means of sweet oil from the powdered rind is used as a stimulating liniment, and is also used in perfumery soap. Essential oil of flowers and leaves extracted in the same way is considered to have the same properties. Kernel is eaten and preserved in sugar. Leaves are used in flavouring. The drug is used in scorpion-sting and snake-bite.
Herbal based Soaps & Shampoos
A Typical Batch for Household Herbal Washing Bar Soap
For 200 Kg. of Finished Product
| |
Kg. |
| Palm oil |
20.0 |
| Mahua oil |
21.0 |
| Groundnut oil |
21.0 |
| Ricebran oil |
22.0 |
| Coconut oil |
11.0 |
| Rosin |
2.0 |
| Shikakai |
55.0 |
| Sodium silicate, 40 percent |
33.3 |
| Soda ash |
10.0 |
| Solvent naphtha |
2.5 |
| Sodium hydrosulphite |
2.0 |
| Perfume |
0.1 |
| Anhydrous soap content |
50 percent |
| Water content |
32 percent |
Formulations for Herbal Washing Soaps
As mentioned before, generally coconut oil, olive oil are spared in preparation washing soaps. But these are other low titer oil soaps and some potassium soft soaps are best prepared by semi-boiling/cold-made process.
Depending upon the availability of raw fats and oils, variation in the proportion of fatty oils are to be made. Combination hard fats and soft fats (oils) are to be established keeping additional consideration of their fatty acid composition. In some cases balance in acid composition may be obtained adding required quantity of free fatty acids to the fatty oils mixture.
Hard Fats are
Tallow, Palm oil, Lard, Greases etc. Non availability of one hard fat may be compensated by correct estimation of other available hard fats.
Soft Fats are
Coconut oil, Olive oil, Groundnut oil, Cotton-seed oil, Palm kernel oil, Babassu nut oil, ricebran oil, Corn oil, Castor oil and more other oils.
As coconut oil and its substitute palm kernel oil and babassu nut oil produce best soaps, these are costlier oils so cheaper oils and fats are used for making washing soaps.
Some Suggested Formulations for Washing Soaps
1. Good Quality
| |
Kg. |
| Mahua Oil |
28 |
| Palm Oil |
30 |
| Coconut Oil |
38 |
| Rosin |
2 |
| Caustic soda solution. 36oBe |
52 |
| Sodium silicate, 40 percent |
37 |
| Sodium carbonate |
10 |
| Sodium hydrosulphite |
2.5 |
| Perfume |
0.2 |
[/br]
2. Cheaper Quality
| |
Kg. |
| Ricebran Oil |
20 |
| Groundnut Oil |
9 |
| Cottonseed Oil |
30 |
| Mahua Oil |
20 |
| Palm Oil |
-18 |
| Rosin |
3 |
| Soapstock (cottonseed Oil) |
15 |
| Caustic soda lye, 36oBe' |
52 |
| Sodium silicate, 40 percent |
35 |
| Sodium carbonate |
10 |
| Stannous Chloride |
2 |
| Perfume |
0.2 |
In the preparation of soap with soap stone as filler, soap stone is to be added to the molten oil before saponification and kept in suspension by agitationuntil the saponification begins and the saponified mass becomes thick and homogeneous.
3. Cheaper Quality
A Typical Batch for Herbal Based Toilet Soap Oriental type
| |
Kg. |
| Mhua oil |
22.0 |
| Palm oil |
16.5 |
| Ricebran oil |
33.0 |
| Groundnut oil |
16.5 |
| Castor oil |
5.5 |
| Soapstock of cottonseed oil |
5.5 |
| Caustic soda Iye, 36oBe' |
50.0 |
| Sodium silicate, 40 percent |
37.0 |
| Sodium carbonate |
10.0 |
| Foam booster |
1.0 |
| Sodium hydrosulphite |
2.5 |
| Colour pigment |
0.02 |
| Solvent nephtha |
2.5 |
| Perfume |
0.05 |
Perfume mixture as formulated below
| |
Kg. |
| Coconut oil |
30 |
| Salsa |
50 |
| Chitrak |
20 |
| Caustic soda Iye 39o Be' |
46 |
| Colouring matter (windsor Brown) |
0.005 |
| Sodium Hydrosulphite |
1 |
| Perfume mixture |
0.403 |
| Bargamot oil |
0.108 |
| Sassafras oil |
0.108 |
| Clove oil |
0.108 |
| Thyme oil |
0.108 |
| Oil of meroli |
0.050 |
| Tincture of mask |
0.020 |
Formulation for Superfatted Soap (for dry skin)
| |
Kg. |
| Neem oil |
66.00 |
| Coconut oil |
30.00 |
| Castor oil (bleached) |
4.00 |
| Caustic soda Iye, 39o Be' |
45.00 |
| Bachh |
1.00 |
| Deodar |
1.00 |
| Colour-pink |
0.05 |
Perfumes as formulated below
Perfume Mixture
| Geranium oil |
0.310 |
| Bargamot oil |
0.310 |
| Lavender oil |
0.062 |
| Vetiver oil |
0.062 |
Mostly the superfatted soaps have tallow : Coconut oil ratio of 50 or 60: 40 and have 7 to 10 percent free fatty acids added in it. Soap For Excessive Oiliness in the Skin.
For such type of soap the soap base is incorporated with about 5 percent soda ash.
Formulation of fancy Soap Type
| |
Kg. |
| Coconut oil |
40.00 |
| Malethi |
60.00 |
| Caustic soda Iye 35oBe' |
55.00 |
| Stabilizer |
1.00 |
Perfume Mixture
| Geranium oil |
0.280 |
| Bergamot oil |
0.280 |
| Citronella oil |
0.140 |
| Lavender oil |
0.012 |
| Vetever oil |
0.009 |
Himalayan Boquet Type Parts
Colour-
| Coconut oil |
40.000 |
| Antamul |
60.00 |
| Caustic soda Iye, 38oBe' |
49.500 |
| Stabilizer |
1.000 |
| Brilliant Soap Green |
0.105 |
Perfume Mixture :
Rose Soap Type :
| Bargamot oil |
0.280 |
| Palmarosa oil |
0.140 |
| Lavender oil |
0.280 |
| Lemon oil |
0.140 |
| Cedar wood oil |
0.180 |
| Tincture of Mask |
0.020 |
| Coconut oil |
95.00 |
| Castor oil (refined) |
5.000 |
| Caustic soda Iye, 38oBe' |
54.500 |
| Stabilizer |
1.000 |
Perfume Mixture :
| Palmarosa oil |
0.205 |
| Lavender oil |
0.205 |
| Citronella oil |
0.205 |
Transparent Soap - No. 1.
(glycerine soap of market)
The transparent soaps vary greatly in composition. Usual method of manufacture is to add alcohol and glycerol in the proportion of 2 : 1 to a not saponified batch of semi-boiled soap until a rapidly cooled sample is clear, after which the batch is put into frames in the usual way. Sugar may also be added. The fats used in transparent soap are tallow and coconut oil. Upto about 30 percent castor oil is often used in the fats charge since the presence of this oil reduced the amount of alcohol, glycerol or sugar required to render the soap transparent. The anhydrous soap content of transparent soap is well under 50 percent.
A suggested formulation
| |
Kg. |
| Coconut oil |
60 |
| Babul gum |
34 |
| Castor oil |
25 |
| Caustic soda Iye 38oBe' |
68 |
| Stabilizer |
1.2 |
Composition of sugar, water, alcohol and glycerol to be added to the saponified mass :
| |
Kg. |
| Sugar |
40 |
| Water |
45 |
| Alcohol |
20 |
| Glycerol |
10 |
The perfume mixture from following ingredient is to be mixed with the finished soap before pouring into the frames
| Lemon oil |
3 parts |
| Geranium oil |
2 parts |
| Palmarosa oil |
10 parts |
| Bergamot oil |
0.5 parts |
The colour added is water soluable red soap colour.
Transparent Soap-No.2(by special milling method)
| |
Kg. |
| Coconut oil |
22 |
| Salai gum |
65 |
| Castor oil |
13 |
| Caustic soda Iye, 39oBe' |
46 |
The fats and oils are purified, then saponified with pure caustic soda lye. The transparent, hot soap paste is there upon applied to cooled rollers in such a manner that in the course of 2-3 seconds the temperature is reduced from about 95oC to about 20oC. The ribbons are perfumed along with added preservatives and milled once or twice on cold rollers. Then the soap mass with an anhydrous soap content of about 71 percent, is passed through a slowly operating plodder, the head of which is cooled. The extruded strip of soap is cut in to chips or cakes. The soap obtained is extremely transparent and is ready for packing. When stored, the soap will dry without altering its shape. The soap has a final anhydrous soap content of about 73 to 75 percent.
Mottled Soap
The coloured streaks, for example, blue in a mottled soap are interspread with a white, cream or any other light colour are due to the presence of a small amount (25 percent) or as desired, of ultramarine blue added to the soap kettle before the soap is finished. Adding excess alkali, the niger is kept unseparated from the soap and as such poured in the frames in the form of two distinct but intermingled phases, only one of which contains colouring matter. The final appearance of the soap is developed by very slow cooling in the frames.
The mottled soaps are also prepared by hand mixing carefully of a coloured and uncoloured base.
Carboli Acid Soap
The soap is made by addition of commercial carbolic acid so that is has an appeal of disinfectant value. But phenolic constituent nearly impart a disinfectant odour to ordinary toilet soap. The soap is conventionally coloured with a red dye. This type of soap is also manufactured in liquid form.
Suggested Formulation
| |
Kg. |
| Coconut oil |
90.00 |
| Groundnut oil (refined) |
80.00 |
| Castor oil (refined) |
10.00 |
| Caustic soda lye, 38oBe' |
90.00 |
| Muleth |
2.00 |
| Stabilizer |
0.90 |
| Red soap dye (Oil Red) |
0.20 |
| Water to dissolve dye |
2.00 |
Procedure
The colour dye is first dissolved in 2 kg. of water. Then the solution is mixed with caustic soda lye. The filtered solution is then added gradually to oil mixture preheated at 80o to 90oC for saponification while the mass is well agitated. After addition of alkali solution is completed, the reacted mass is crutched for an additional period of 30 minutes while heating is maintained.
Then heating is stopped and stabilizer is added and mixed. The saponified mass is allowed to be cooled down and then carbolic acid is added to the viscous soap and intimately mixed by maintaining agitation.
The molten soap is finally framed, cooled, cut, rack-dried, stamped, wrapped and packed as described before.
Medicated Soaps
These soaps are prepared taking soap-base obtained by saponification of purer grade oils and given the finishing through milling process. In the milling operation the medicinal agents such as mercuric iodide, sulphur, iodine etc. are incorporated.
Castile Soap
It is less irritative to the skin than ordinary toilet soaps and hence it is a medicinal soap and a soap for infants.
It is prepared from pure olive oil usually by cold-made process. A mixture of oils which approximates the fatty acids composition of olive oil (Table-2) may also be used for making castile soap.
It is a hard soap of white or yellowish white in colour. The mildness of castile soap is due to the absence of capric and lauric acid soap (source of skin irritation) present in the coconut oil and similar oil soaps.
Preperty of good solubility can be achieved in the castile soap by preparing it using oil composing largely of oleic acid, thereby avoiding coconut oil for such solubility benefit. Refined groundnut oil with added quantity of free oleic acid with corresponding amount of glycerol may made a mixture nearly equal to the composition of olive oil.
The finishing operations are as like that of toilet soaps.
CASTILE SOAP BY BOILING PROCESS
Process Description
Step 1 : 1000 kg., of crude olive oil and 675 litre of caustic soda lye of Sp. Gr. 1.09 are put in the pan. The mixture is boiled with live steam for three hours then sufficient quantity of salt is added in to it to separate the spent lye. Supply of steam is stopped and the whole mass is allowed to rest for 4 or 5 hours. Spent lye is drawn off.
Step 2 : 450 litres of caustic soda lye of Sp. Gr. 1.160 is added into the soap mixture and boiled again for 4 or 5 hours, taking care that the soap does not boil over the pan. Spent lye is again separated by addition of salt and following previous method. Spent lye is drawn off and the mass is boiled again with addition of 490 litres of caustic soda lye of Sp. Gr. 1.210.
Step 3 : Final operations are followed as described in the finishing of full-boiled milled toilet soap adding necessary perfume and preservatives.
Some Suggested Formulations for Castile Soap
| |
No. 1 |
No. 2 |
| |
Kg. |
Kg. |
| Olive oil |
40 |
30 |
| Groundnut oil |
30 |
- |
| Cottonseed oil |
- |
30 |
| Babchi |
30 |
40 |
| |
No. 3 |
| |
Kg. |
| Olive oil |
30 |
| Cocoa butter |
30 |
| Palm karnel oil |
40 |
| |
No. 4 |
| |
Kg. |
| Palm oil (bleached) |
50 |
| Sesame oil |
20 |
| Chitrak |
30 |
The caustic soda lye used in the corresponding steps as described before are :
67.5 litres of Sp. Gr. 1.090
45.0 litres of S.P. 1.160
56.0 litres of Sp. Gr. 1.210
Translucent Coconut Oil Soap
| Coconut oil |
20 Kg |
| Caustic soda lye, 36o Be' |
10 Kg |
| Caustic potash lye, 30o Be' |
1½ Kg |
| Oil of anise |
60 gm |
| Oil of peppermint |
40 gm |
The coconut oil is first saponified with caustic soda and then caustic potash is added with constant stirring. The mixture is then heated gently until the saponified mass becomes clear. After about an hour the kettle is uncovered and oil of anise and oil of peppermint are added and well mixed. Final finishing may be given as desired.
Some Suggested Formulations for Disinfectant Soaps
No. 1 Parts
| Sulphonated Neem oil |
99 |
| Mercuric chloride |
1 |
| Soda ash to neutralise |
required quantity |
No. 2
| Cocoa butter |
48 parts |
| Ammonium sulphate |
20 parts |
| Water |
19 parts |
| Mercuric iodide |
1 part |
| Soda ash to neutralise |
required quantity |
Liquid Antiseptic Soap
| Cottonseed oil |
100 kg. |
| Alcohol |
66.6 litres |
| Water |
150.0 litres |
| Sodium hydroxide |
15 kg. |
| Potassium carbonate |
3.33 kg. |
| Ether |
5.0 litres |
| Phenol (liquified) |
8.33 litres |
The oil is taken in a pan and then 33 litres of water and 66.6 litres of alcohol are added in to it. The mass is mixed thoroughly with the help of agitator. Sodium hydroxide and potassium carbonate being dissolved in 110 litres of water is added slowly to the oil mixture with stirring. For colouring, water soluble Rhodamin derivative of requisite quantity (proportion mentioned before while discussing colouring of soaps) is first dissolved in 7 litres of water and then added to soap mixture. Finally phenol and ether are added and thoroughly mixed.
Deodorant Soaps
These soaps, classed toilet soap are prepared by the process like that of medicated soaps. In the milling operation deodorizing ingredients are incorporated. Some of the deodorant soaps are superfatted.
Modern anti-microbial agents have largely replaced the phenol, cresylic acid formulations of soap.
There are three most commonly used classes of anti-microbial agents used in toilet soaps of today. These are :
bis (hydroxy phenyl) alkanes; poly brominated salicylanilides; halogenated carbanilides.
These agents effectively suppress the growth of Gram-positive skin bacteria responsible for body odour at low concentrations. The following two combinations of anti-microbial agents are recommended to be used in deodorant toilet soaps which have superior inhibition power of growth of large number of bacteria over a non medicated toilet soap.
Combination in Soap No. 1.
| Darhald |
0.75 percent |
| Babchi |
0. 75 percent |
Combination in Soap No. 2
| Mulethi |
0.67 percent |
| Khus |
0.67 percent |
| Duk |
0.67 percent |
VARIOUS INDUSTRIAL SOAPS
Textile Soaps
For scouring and cleansing operations in the manufacture of textiles, various special soaps are in use.
Textile soap must be easily soluble at low temperatures and are free from any builders.
Cheaper fats are used for soap making. Little or no tallow or coconut oil is used to prepare the soaps.
The mostly used fats of textile soaps are-corn, cottonseed, groundnut oil fats, olive oil fats, palm oil, greases, red oil (red liquid obtained during refining of stearic acid by press method. This red oil after separation of stearic acid is mainly composed of oleic acid). In some special formulations coconut oil and its substitute palm kernel oil are preferred.
The alkali used is mostly caustic soda. The processes followed are cold-made and semi-boiled processes.
Some of the uses are
Silk after degumming with enzyme is treated with an olive oil soap solution having 5 gm. of soap per litre at a temperature of 65oC.
In the scouring treatment of acetate rayon, olive soap to the extent of 450 gm. per 4.5 litres of bath solution along with other chemicals at a temperature of 65o to 75oC is used. In the bleaching of acetate rayon, red oil soap is used along with other bleaching compounds.
In some bleaching powder, soap prepared from fats and oils as mentioned before is used.
Textile Bleaching-Washing Soap Powder
| |
Kg. |
| Soap powder |
49 |
| Sodium perborate |
15 |
| Sodium hexa meta phosphate |
10 |
| Soda ash |
9 |
| Magnesium silicate |
1 |
Laundry Soap Formulations
| |
Kg. |
| Finished soap |
500.00 |
| Soda ash |
7.00 |
| Wax/Rosin (1:1) |
11.00 |
| Sodium silicate 40o Be' |
0.02 |
| Soap stock |
20.00 |
| Sodium carbonate solution (30 percent) |
11.00 |
Careful choice of fats and oils with appropriate proportions are to be used in making soap.
For textile cleaning other products are described while dealing with synthetic detergents.
More Formulations
No. 1
Coconut oil fatty acids70
No. 2
| |
Kg. |
| Neem oil |
30 |
| Soda ash |
30 |
| Potassium carbonate |
5 |
| Sodium perborate |
12 |
| |
Kg. |
| Mixture of groundnut oil and palm kernel oil fatty acids |
100 |
| Soda ash |
33 |
| Potassium carbonate |
10 |
| Sodium perborate mixed |
28 |
| with sodium silicate (1 : 1) |
No. 3
| Fatty acids |
100 |
| Benzene, Xylene or |
| Hydrogenated hydrocarbons |
22 |
| Soda ash |
30 |
| Potassium carbonate |
5 |
| Sodium perborate |
16 |
In formula 1 and 2 fatty acids are saponified with alkali at 35oC, just before the mass becomes viscous sodium perborate is added.
The final products may be powdered; extruded to filaments; platelets: needles etc.
Some Soap-Bases other than Genuine Soap used in Textile Cleaning Preparations :
Curd Soap : This soap is inferior to genuine soap. During the final graining stage of soap boiling process the composition of lye on which the soap is boiled is maintained as such that some what open grain soap-curd rests on a lye consisting of salt solution containing small amount of caustic soda.
Marbelised Soap : In manufacturing curd soap, using low quality fats (grease, bone-fat etc.), when impurities as nigre is not allowed to be separated which on cooling segregate in the form of veins in the soap is called marbelised soap. The process is done by finishing soap on lye some what stronger in alkali.
Marseilles Soap : Curd soap of lower quality than marbelised soap is marseilles soap.
Laundry Washing Aids
Detergent properties of washing compounds are greatly increased by incorporating finely divided solid matters in it. These assist in the, mechanical removal of the dirt from the fabrics.
Various formulations of such different mixtures, the addition of any one to the laundry water gives satisfactory result.
| |
No. 1 |
No. 2 |
| |
Parts |
Parts |
| Bentonite |
50-70 |
75-85 |
| Soda ash |
30-50 |
- |
| Caustic soda |
- |
15-25 |
| |
No. 3 |
No. 4 |
| Bentonite |
75-90 |
75-85 |
| Trisodium phosphate |
10-30 |
- |
| Sodium borate |
- |
15-25 |
In all the above formulations sodium silicate may also be used in proportions ranging from 20-40 percent.
More Laundry Wash Mixtures FORMULA-1
(Soap and metasilicate dry mixture)
<th colspan='3' align='center'>Where different mixture are used for breaks and suds
| Where one mixture is used for break and suds |
| | | Break | Suds |
| Soap |
3 Kg. |
3 Kg |
2 Kg. |
| Sodium metasilicate |
2 Kg. |
4 Kg. |
1 Kg. |
(Soap and Sodium Metasilicate Solution)
FORUMLA-2
<th colspan='3' align='center'>Where different mixture are used for breaks and suds. ..
| Where one mixture is used for break and suds |
| | | Break | Suds |
| Water |
450 litres |
450 litres |
450 litres |
| Soap |
14 Kg. |
10 Kg |
14 Kg |
| Sodium metasilicate |
7 Kg. |
14 Kg. |
7 Kg |
A Fabric Cleaning Compound
50-70 parts of bentonite together with 30-50 parts of sodium carbonate are dispersed in water maintaining bentonite in highly fluid condition beyond the maximum jell effect on the bentonite. There a small amount of soap is also to used with the composition.
Cotton Scouring Soap
Water500 litres
| Tallow |
112 Kg. |
| Caustic soda solution, 30 percent |
46 litres |
First tallow is melted and then saponified with the addition of caustic soda solution. The mass is boiled for 5 hours. Final quantity of water is added to make up the volume. This is used for scouring cotton cloth.
Dry Cleaner's Soap
This is a solvent soap, paste or liquid containing 10 to 15 percent of actual soap. Dry cleaning operation is done with organic solvents, hence the soaps used are prepared in such a way that these are easily soluble in cleaner's solvents.
Saponification reaction is carried out in a medium of organic solvent to make soap with an excess of 5 to 10 percent oleic acid as free fatty acid.
Calcium and magnesium oleates are used in the dry cleaning industry where they serve as detergents and help to reduce the fire hazard caused by volatile solvent.
The soap is mostly prepared using triethanol amine as base instead of caustic potash. Tryethanol amine soap is easily soluble in cleaner's solvent as well as in water. Minimum quantity of water is used during soap making.
The cleaner's solvent used is generally trichloro ethylene. Though carbon tetrachloride also finds its use as solvent, it is more toxic by inhalation and skin absorption.
Diethylene glycol or triethylene glycol is incorporated as softener.
A sugested Formulation of Dry Cleaner's Soap
| |
Kg. |
| Oleic acid |
25.00 |
| Caustic potash |
5.00 |
| Water |
8.75 |
| Trichloro ethylene |
250.00 |
| Diethylene glycol |
12.00 |
First caustic potash solution is made with 8.75 litre of water 25 kg. of oleic acid is mixed with 25 kg. of trichloro ethylene in saponifier. Then caustic potash solution is added slowly with stirring to make oleic acid soap in presence of solvent. After saponification is complete, 12 kg. of diethylene glycol is added and mixed with soap mass. Finally the whole product is dissolved in remaining 225 kg. portion of trichloro ethylene.
WATER SOFTNER
(Chemicals which may be used for prevention of soap curds)
Sodium metaphosphate and sodium metaborate prevent the formation of soap curds and even dissolved calcium and magnesium soaps. For this reason they may be used in laundries to make the clothes whiter and saving in soap. They are excellent for rinsing the hair after is has been washed to remove any remaining soap.
JELLY SOAP/ SOFT SOAP
Jelly soap is mostly used by textile working units and in dry cleaning trade.
Jelly soaps are made by semi-boiled process. Potash soap of low titeroils containing 40 percent or more water having jelly like consistency are termed soft or jelly soaps. Cheaper quality jelly soaps are made by using inferior quality grease along with castor oil.
Instead of potassium hydroxide as a whole for saponification of base, mixture of sodium and potassium hydroxide is used for making jelly soaps. Sodium stearate helps to impart jellying property.
Some soaps are made with oleic acid and ammonia and petroleum naphtha or ethyl acetate containing 30 percent hydrocarbon forming a gelatinous mass. The best soap contains about 5 percent excess unsaponified fats. Jellyfication property helps to retain other substances incorporated in the soap, thus enabling to manufacture various kinds of special soaps.
AUTOMOBILE SOAP
It is marketed in the form of paste. The soap is prepared by saponification of linseed oil, corn or soyabean oil with caustic potash. Usually these are superfatted soap. There is no difference between linolium floor soap and automobile soap except that the former is liquid.
WIRE DRAWING SOAP
The soap is made by saponifying tallow or grease with caustic soda having talc as filler.
SCOURING SOAP
These soaps are manufactured in the form of bar, paste or powder containing one or more finely powdered insoluble abrasive materials chosen to assist particular job such as :
Washing of Mechanics Hand;
- Pots;
- Tiles;
- Walls;
- Floors;
Abrasive materials include talc, pumice, quartz and feldspar. Alkaline builders such as sodium silicate, trisodium phosphate, sodium carbonate are incorporated. Soap content of such products are generally not required to be kept above 10 percent, as not great amount of sudsing is desired.
A mechanic's hand washing soap is made from coconut oil in which pumice is incorporated to the extent of 50 percent of soap. The soap also contains sodium silicate as additive. Abrasive material helps to remove dirt or grease from hands.
PREPARATION OF WASHING SOAP POWDER
Simplified Method
In a batch of 50 kg. of molten soap the following ingredients are added and well-mixed :
| Sikakai(dissolved in minimum quantity of water) |
1 kg. |
| Sodium silicate, Sp. Gr. 1.375 |
10 kg. |
| Sodium carbonate (anhydrous) |
22.5 kg. |
When the temperature is below 50oC, then 9.5 kg. of sodium perborate is added and the mixture is reduced to powder.
SHAVING SOAPS
The Desirable Properties of Shaving Soap are :
- It should produce thick good lather.
- It should be slow drying.
- The soap should not contain any alkali.
- It should be hard but not too hard and not insoluble.
A combination of potassium soap and sodium soap having good amount of stearic acid and glycerine gives slower drying, close, thick lather with desirable hardness and solubility.
To ensure no alkali, the soap is superfatted with 0.5 to 1 percent stearic acid.
Procedure
The soap is made by cold-made or semi-boiled process so that it contains certain amount of glycerine.
To have good amount of stearic acid soap in the final product the initial fat charge usually contains atleast one third of total fats as commercial stearic acid.
Coconut oil or palm kernel oil is generally used to the extent of 25 to 35 percent. The remainder fats may be tallow, palm oil etc.
To minimise hardness and to increase solubility of the soap, the saponification reaction is done with a mixture of caustic potash and caustic soda solution. The percentage of potash soap may vary but not be less than 50 percent of total soap.
A Typical Charge
| |
Kg. |
| Coconut oil |
25.00 |
| Babul gum |
40.00 |
| Dhania |
35.00 |
| Caustic potash, 38o Be' |
23.00 |
| White pigment |
0.50 |
| Stabilizer |
0.50 |
| Additional stearic acid |
1.00 |
| Perfume |
0.15 |
The soap is prepared by semiboiled process in a stainless steel pan and after saponification is complete, a test samples should indicate no free alkali (dissolving small sample of soap in distilled water and then adding few drops of phenolphthalein indicator to it, a persistent pink colour indicates free alkali). Then glycerine and excess quantity of stearic acid is added. Finally pigment, preservative and perfume are added and intimately mixed.
The product may be given extrusion finish using plodder followed by extruder having round or rectangular opening. Finally cutting, superficial drying, stamping, and packing make the finished soap.
Shaving Cream
Characteristics of shaving creams are similar to that of shaving soaps except that the former remains in soft plastic form to be easily pressed out from tube and the later is a hard soap.
There are shaving creams having their composition different. The most extensively used type is made with the same raw materials as are used in the preparation of shaving soap with a necessary change in their proportions.
Higher proportion of stearic acid with correspondingly lower proportions of coconut oil and tallow or palm oil are used.
The ratio of potassium soap to sodium soap is maintained at 5 :1.
In the final product upto 5 percent free fatty acids are allowed to be present as superfatting of cream. This is done by liberating fatty acids from finished soap cream by addition of calculated amount of dilute sulphuric acid or hydrochloric acid or boric acid.
The lusture and softness of the body of the cream is due to the presence of large percentage of free stearic acid and glycerol (5-10 percent).
The cream usually contains about 35 percent anhydrous soap.
A Typical Charge
| |
Kg. |
| Coconut oil |
20.00 |
| Khus |
30.00 |
| Stearic acid |
50.00 |
| Caustic potash, 28o Be' |
19.00 |
| Glycerine |
7.00 |
| Boric acid |
1.00 |
| Stabilizer |
0.50 |
| Perfume |
0.15 |
| Additional water |
115.00 |
Caustic potash and caustic soda lye are first prepared with requisite quantity of water. The two are mixed together and heated to about 80oC and then glycerine is added to it. The mixture is kept ready. Coconut oil, tallow and stearic acid are melted in the saponification pan, temperature being brought to about 80oC with water bath heating system. Then caustic lye mixture with glycerine is added slowly to the fatty mixture in the saponification pan with efficient stirring. When saponification is complete, balance quantity of water which is also heated to the same temperature is added to the soap mass. Addition of stabilizer, lanolin etc. (antioxidant) and then boric acid is made. The cream is allowed to be cold then perfume is mixed and kept as such for 2 to 3 days before filling in tubes by filling machine.
Other Formulation
| |
Kg. |
| Stearic acid |
15.00 |
| Coconut oil |
5.00 |
| Emblic myrobalan |
15.00 |
| Potassium hydroxide, 28o Be' |
33.00 |
| Sodium hydroxide, 18o Be' |
6.30 |
| Shikakai |
9.00 |
| Lanolin |
1.00 |
| Other additives |
1.00 |
| Kala Bhangra |
1.00 |
| Perfume |
0.10 |
| Additional water |
30.00 |
Brushless/Latherless Shaving Cream
Brushless creams are oil-in water emulsions. The oil may be mineral oil or vegetable oil. Stable emulsion is made with special soaps which also help wetting the beard and their subsequent absorption of water.
In one type, the aqueous phase consists of paste of superfatteo potassium soap of stearic acid.
In other type triethanol amine soap is used instead of potassium soap.
Others are composed of sulphonated tallow or sulphated oils as surface active agents.
All types contain 70 to 80 percent water consistent with the proper body.
LIQUID SHAVING CREAM
Basic Combination
| |
Part |
| Gum rosin |
200 |
| Triethanol amine |
10 |
| Water |
800 |
Thicker Cream
| Gum rosin |
200 |
| Triethanol amine |
10 |
| Andydrous sodium carbonate |
10 |
| Water |
800 |
Aerosol Package
The compound consists of an aqueous solution of detergent with a propellant in it. The propellant is a easily liquified halocarbon and is immiscible with aqueous detergent solution.
The container in which the compound is packed is designed in such a way that it generates and delivers shaving creams as a foam.
Liquid Soaps/Shampoos
Liquid soaps may be classified as
- Liquid Toilet Soaps, such as
- Dispenser's soap
- Soaps used in public wash rooms
- Other specific purposes soaps
- Liquid Washing Soaps, such as
- Soap used for washing linolium, tiles; composition floors in office, schools, institutions and various public buildings, etc.
- Shampoos
Process of Manufacture
All the liquid soaps are manufactured undergoing following steps :
Step 1 : Saponification for concentrated soap base by semi-boiled process.
Step 2 : Dilution of concentrated soap with requisite quantity of water.
Step 3 : Chilling and filtering of the diluted soap.
Step 4 : Incorporation of perfume and colouring matter and if needed addition of alcohol to prevent further solidification on cooling.
Step 5 : Packing.
EQUIPMENTS
- A jacketed saponification kettle fitted with stirrer, made of stainless steel.
- Caustic potash solution tank made of stainless steel.
- A chilling unit.
- A vacuum filtration unit.
- Storage tanks.
- Packaging unit.
LIQUID TOILET SOAP CONCENTRATES
These are made by saponifying mainly coconut oil mixed with soft oils, such as cottonseed oil, ground nut oil, soyabean oil etc., with caustic potash. The concentrated soap base is usually diluted with water to an anhydrous soap content of about 15 percent.
Some suggested Formulations
For Office use
| |
Kg. |
| Coconut oil |
126 |
| KOH solution, 38o Be' |
90 |
| Glycerine |
17 |
| Water |
560 |
For Workshop use
| |
Kg. |
| Coconut oil |
220 |
| KOH solution, 38o Be' |
157 |
| Glycerine |
26 |
| Water |
418 |
Perfume and colouring matter are added as desirable. Formulation of Dispenser's soap is given before while describing medicated soaps.
Soap Bubble Liquid
| Castile soap |
30 g. |
| Glycerine |
120 c.c. |
| Distilled water |
240 c.c. |
The soap is dissolved in water then glycerine is added and mixed thoroughly. The liquid mass is allowed to stand until it is cleared at the bottom which is siphon off or separated by other means and is ready for use.
LIQUID WASHING SOAP CONCENTRATE
The liquid washing soaps are made by saponifying linseed oil or soyabean oil with caustic potash and are superfatted with free fatty acids because there should remain no alkali residue after floor is washed. The soap base is then diluted with water to an anhydrous soap base is then diluted with water to an anhydrous soap content of about 25 percent. The soaps are usually compounded with small amount of pine oil.
Technology of Manufacturing Herbal Synthetic Detergents
The formulation of herbal based detergent powders is indeed a challenging task in the Indian context, since it must take into account the purchasing power of different sections of the population while offering a good detergency. A variety of detergents, varying widely in price and performance characteristics produced by, the small-scale as well as by the organised sector are being marketed. In general, the small-scale sector produces detergent powders by the dry mix route whereas the organised sector produces the bulk of the powder by the spray drying route although in recent times the latter are also following the dry mix route for some of the powder detergents. Heavy duty liquid detergents have not yet become popular because of price constraints.
Performance Criteria
The formulation of a detergent powder normally takes into account the following factors.
- The washing habits
- The quality of water used for washing (iron content, hardness)
- The nature and extent of soiling
- White vs. coloured clothes
- Facilities available for manufacture (dry mix vs. spray drying route).
- Safety and pleasant 'in use' qualities
- Pleasing colour, odour and flow characteristics
- Long shelf life
- Pricing
1. Washing habits
The normal practice is to dissolve the powder in warm or hot water, soak the clothes for some time, squeeze and rinse. Profuse lather is a chief requirement in this case. For use in washing machines, low foam detergents are preferred.
2. Quality of water
In India, the hardness of water varies widely and the detergent powder must incorporate a water softener in the formulation, either for precipitating calcium and magnesium salts or for chelating them.
3. Soiling
In India the extent of soiling is fairly severe, especially in large cities, which necessitates the formulation of heavy duty detergents. Soil mainly comprises collar and under arm stains, caused by dirt/particulates/sweat/oily matter and also from atmospheric pollution that settle on the main body of the clothes.
4. White vs. coloured clothes
In spite of good intentions, white and coloured clothes are seldom washed separately with the result that no separate formulation exists for the whites and coloured. Added complications sometimes result from the running of colours and their deposition on other coloured or white garments being washed together.
5. Manufacturing facilities
The spray drying route for detergent powder is capital and energy intensive. Therefore, this route is mainly followed by the organised sector. On the other hand the small-scale or cottage sector follows the 'dry-mix' route since hardly any capital equipment other than pots and pans is required. Formulation by the dry-mix route is far more flexible and as a result in small-scale sector the bulk of the detergent powders are of this type. Efforts are however now being made by the organised sector to produce dry mixed powder for reducing costs and possibly for improving efficacy.
6. Safety and pleasant 'in-use' qualities
The advantage of spray dried powder is that the powder is more uniform and dissolves in water easily. The powder is also generally kinder to the skin as compared to powders produced by the dry mix route which have higher soda ash levels responsible for skin irritation on prolonged contact.
7. Colour, odour and flow characteristics
The flow characteristics of spray dried powder are generally superior to those of dry-mix powders. The former can however give rise to dust in handling if the moisture content is not kept under control. Colour and odour of powders manufactured by both the routes are comparable.
8. Shelf life
With moisture proof packaging, the product is generally well protected and remains satisfactory for several months.
9. Pricing
Pricing is a function of formulation, packaging and government incentives if any. There is such a keen competition between the small-scale and organised sector that the latter has been compelled to re-align some of their formulations in order not to be widely different from those adopted by the small scale sector.
Formulation Requirements
For maximum cost effectiveness, conventional detergent powder should be optimised to match user requirements and brand positioning. Two criteria for formula optimisation are :
- Alkalinity
- Good building and adequate levels of active matter
- In any organised study, it is necessary to employ a computer modelling technique using formulation details and wash solution data, and matching them with two criteria viz. free calcium and micellar active concentrations. A control formulation serves as a standard for comparison of results.
1. Alkalinity
The pH should be maintained at a level of 10 to 11 throughout the wash. This ensures maximum Calcium-STPP binding leading to good detergency.
2. Good building and active matter
In good building, the STPP level and pH (up to 11) must give low free Ca++ so as to produce good detergency and oil suspension (anti-redeposition). The AD level should be adequate to give high micellar active concentration in solution leading to good foaming and detergency.
The most cost effective way of introducing reserve alkalinity into a product is sodium carbonate. No other equally cost effective alternative buffering agent is available.
Approach to Product Formulation
The ingredients commonly used in the formulation of a good grade powder, their level of usage, technical benefits, and key variables are given in Table 4.1.
Item Nos. 3 and 4 are used selectively under Indian conditions by the organised sector. A few typical formulations (Nos. 1-4) used by the organised sector are listed in Table 4.2 along with two others (Nos. 5 and 6) that are similar to those followed by small-scale manufacturers.
Ingredient Usual level %Technical benefit Key variable
- Active Detergent 18-20 Soil removal, foaming, all temperatures Actual concentration in wash
- Phosphate 22-32 Softens water by binding Ca, Mg 'Free' level of Ca
- Perborate 10 Oxidative bleaching, removal
- of chromophoricConcentration of H2O2 in
- stains at over 60 0C. the wash
- Enzyme 1 Removes protein stain at Total integrated
- less than 50 0C. enzyme active conc. x Time at
- given wash temperature.
- SCMC 1-3% Prevents soil redepo- Amount of
- @ 50% sition on fabric adsorbed
- active SCMC on cotton.
- Fluorescer 0.2-0.4 Increased whiteness and Quantity of fluo-
- brightness of white rescer present in
- cotton fabric the wash in
- relation to total cotton load.
Table 4.2 Non Soapy Detergent Powder Formulations
| |
1 |
2 |
3 |
4 |
5 |
6 |
| AD |
20 |
20 |
18 |
20 |
10 |
12 |
| STPP (Castor Oil) |
22 |
25 |
25 |
32 |
5 |
- |
| Sod. Sil. Alk. (anhy.) |
10 |
10 |
11 |
8 |
5 |
5 |
| Soda ash |
10 |
7.5 |
8 |
- |
45 |
50 |
| Soap Stock (50%) |
1 |
2 |
2 |
1 |
- |
- |
| Na2SO4 |
25 |
23 |
19 |
24 |
20 |
20 |
| Photine C |
0.2 |
0.3 |
0.3 |
0.3 |
0.1 |
0.1 |
| Colour |
0.06 |
0.08 |
0.08 |
0.04 |
0.05 |
0.05 |
| Perfume |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
| NaCl |
- |
- |
- |
1.0 |
5.0 |
4.00 |
| Moisture Inorganics etc. |
100 |
100 |
100 |
100 |
100 |
100 |
Formulation Nos. 5 and 6 are similar to those employed by the small-scale industry and are definitely more affordable for the common man. The formulations listed are applicable to hand washing situations. For washing machines, a low lathering tailor-made product is used. A formulation involving the use of 10% non-ionic component such as tallow alcohol 10 EO, or one with, 14% LABS, 5% soap and 1% non-ionic component gives a low lather. This product is preferred as a washing machine-detergent to prevent lather overflowing from the machine during the washing operation.
Production Procedure
Manufacture of detergent products involves the following principal operations and processes as shown in the flowsheet of Fig. 13.
- Manufacture of linear Alkyl Benzene Sulphonate (LAB Sulphonate)
- Manufacture of Coconut Oil, Tallow Derived Alcohol Sulphates.
- Mixing the above two, Sulphonate and Sulphates in appropriate proportions.
- Neutralization of the mixture with requisite quantity of sodium Hydroxide solution to make Surfactants.
- Mixing Surfactants with builders, fillers, additives in their precalculated proportions.
- Drying in spray dryer for desired granularsize with the help of size separating units, cyclone separator, sieve screening etc.
- Cooling the products.
- Perfuming.
- Packing.
In smaller units, detergent manufacturing process may start from procurement of LAB and coconut oil fatty alcohols. Actual chemical processes to be performed are sulphonation and sulphation and then other finishing operations are performed as mentioned above.
Further smaller units (cottage industries) may start from procurement of LAB sulphonic acid and faty alcohol sulphates (acid slurries). Only neutralization of acid slurry in the chemical process to be performed. Other finishing operations are to be done as described before.
Detergent Bars
Introduction
The detergent bar (also called non-soapy detergent (NSD) bar or detergent cake) was first introduced into the market in the late sixties by the organised sector as a natural corollary to the existence of washing soap cakes. The prices of indigenous soapmaking oils were increasing rapidly while the price of alkylate was attractive in comparison to the level of usage in bars. Weight for weight, synthetic detergents were 1½ to 2 times more efficient than soaps especially in hard water. Taking these factors into account and using a process similar to the toilet soap finishing line, a processing route for detergent bars was developed indigenously. In view of the heavy costs involved in setting up the plant, the production of detergent bars has largely been confined to the organised sector.
Detergent bars constitute about 30% of the 14 lakh tonnes of synthetic detergents made in the country annually. The small-scale sector has now also successfully entered the manufacturing scene. The synthetic detergents bar industry has a bright future since, this offers a more viable alternative both for the producer as well as the consumer, as compared to the manufacture of brown powder.
Requirements of a Detergent Bar
The requirements of a detergent bar are :
- The bar must have superior detergency as compared to washing soaps with a pH maintained around 9-10 during washing.
- The colour must be attractive.
- The bar must have a soft yet firm texture.
- The bar must have a density as close as possible to that of washing soap.
- The bar must not undergo undesirable changes in storage.
- The bar must produce copious lather, must not wear fast or become soggy with use.
- The bar must be pleasantly perfumed and the perfume stability must be assured.
- In brief, the bar must provide all the attributes and more, as compared to washing soaps.
- It was soon realised that the development of an acceptable bar posed one of the most daunting challenges to chemists, chemical engineers and chemical technologists. Research for the removal of some of the deficiencies such as sogginess during use is underway and considerable success has already been achieved.
NSD Bar Vs. Soap
The fundamental difference between a soap and an NSD bar is that while soap comprises a single major organic component i.e. the soap itself, the NSD bar is a heterogeneous mixture of organic and inorganic components compacted into a bar.
While soap behaves in a set pattern and it is easier to process soap chips into the finished product, this is not so in the case of the NSD bar. With every minor change in formulation arising from cost control measures, the processing of the NSD bar can vary. The variation in the density and the size of the bar for the same weight can result in a host of problems. Therefore the formulation and processing of the NSD bar require continuous attention.
In addition, the high degree of wear and tear of the equipments, heat generated during processing, need for weathering of the bar for imparting hardness, and labour intensive-operations are other problems.
The storage and in-use behaviour of an NSD bar is vastly different from that of washing soap. While soap tends to lose weight in storage, the NSD bar gains weight. Since the NSD bar is a heterogeneous mass comprising some water soluble ingredients, there is a need to minimise the in-use contact time with water because prolonged contact could leach out the soluble ingredients, resulting in sogginess and eventual high rate of wear.
Users of the NSD bar have to learn to use the bar in such a way that soggy appearance of the bar is discouraged. This is done by minimising the contact time for rubbing the bar against the clothes, wiping the bar free of water after use and leaving it in a dry state before the next use. For the same reason, the fluted design of the NSD bar has been specially chosen for minimising the contact area with standard soap dishes.
Another undesirable phenomenon that is observed when the NSD bar is left to dry, is a powdery or spotted appearance on the surface. This is basically a function of the formulation and if the bar is otherwise satisfactory, this may be ignored. It is however necessary to formulate the bar in such a manner that the build up of insoluble matter on the fabric is minimised.
A common problem with the blue coloured NSD bar is the staining of fabrics. This can be controlled by minimising the usage of colour, improving the quality of other ingredients and resorting to a correct order of addition of the ingredients in the mixer. This step is less critical in the case of soaps since a very small quantity of colour is used.
The perfumes of NSD bars are generally stable since, unlike soaps, the detergent bars are virtually not susceptible to oxidative rancidity.
Components of Detergent Bars
The main objective of the formulation is to be able to produce a bar which meets all the listed in section 4.6.2 requirements. It should feel like soap while maintaining an overall price-performance advantage over soap. All the additives that have been considered from time to time are discussed below.
1. Active detergent
Initially, while the NSD bar was in a development stage, AD in the range of 30-40% was being considered. High AD bars proved to be too soft. Over a period of time because of the rising price of alkylates, the AD level has been steadily brought down to about 20% in good grade bars. Some manufacturers have brought it down further to 10-12.5 as a cost reduction measure and for offering the product at competitive prices.
The AD originally comprised the sodium salt of dodecyl benzene sulphonic acid but over the years for reasons of poor biodegradability the AD is now based on linear alkyl benzene and is fully biodegradable.
While dodecyl benzene sulphonic acid was more viscous and generally darker in colour it required a bleaching step. The LAB sulphonic acid is less viscous, more easily sulphonated and has a lighter colour without bleaching. From the point of view of the bar and lathering properties for the same AD, the DOB based AD has an edge over LAB.
The active detergent is obtained as an acid slurry and is neutralised in situ in a heavy duty mixer with a mixture of soda ash and caustic soda. Soda ash as such can also be used as neutralising agent but it is necessary to finely grind the material and sieve it before use for preventing the appearance of white specks in the finished bar.
2. Sodium tripolyphosphate
The importance of sodium tripolyphosphate (STPP) as a sequesterant and builder in NSD formulations is well known. However, its usage is being severely restricted in developed countries since it is said to be a major contributor to a process called eutrophication of lakes, rivers and ponds when spent wash water containing detergents and STPP enter them. Eutrophication ultimately leads to increased biological oxygen demand (BOD) in such waters affecting aquatic life.
In India although the eutrophication problem does not appear to be serious, there is an increasing trend to reduce the level of usage of STPP in detergent bar formulations because of price considerations.
Thus from an original level of 25 to 35% in the sixties and seventies the current trend is to reduce the level to 2-16% or even eliminate it altogether, the price factor outweighing the pollution aspect.
Regarding the grade to be used, the fast hydrating variety with a glycerine temperature rise of a minimum of 15oC is preferred from the point of view of the firmness of the bar.
3. Talc
Talc is cheap filler that is freely used in NSD bars, the level depending mainly on cost considerations. A usage level of 10-15% is common. Talc occurs in various degrees of whiteness the price being directly proportional to the whiteness. It is used as a fine powder after passing it through a 200 mesh screen.
4. Starch
Starch is used as binder at a level of 5-10% or less depending on the rest of the formulation. Usage of starch in not a must if more economical substitutes are available.
5. China clay
China clay is a from of hydrated aluminium silicate which is obtained as a mineral. It is treated for the removal of impurities such as iron compounds, sand, mica etc. and is used as a very fine powder.
China clay serves the purpose of a binder and is used to the extent of 10-15% in the formulation as a fine powder passing through 200 mesh.
6. Calcite
Calcite is a widely used filler at levels ranging from 10 to 30%. It helps to reduce cost while being compatible with the formulation. The cheaper NSD bars have higher levels of calcite. The material is used as a fine powder which passes the 200 mesh test.
7. Soda ash
Soda ash is used both as a neutralising agent for sulphonic acid as well as a builder instead of STPP. Usually soda ash is used for neutralising sulphonic acid, the excess being retained in the product as a builder. The extent of the excess soda ash depends on the formulation and is in the range of 10-20%.
8. Sodium sulphate
Sodium sulphate is produced in situ during the neutralisation of sulphonic acid in the mixer. It is usually not included as an external additive since it does not serve any useful purpose and cheaper substitutes offer a price advantage.
9. Sodium silicate
Alkaline silicate of soda is sometimes used since it acts as a synergist in detergency. It has a mild buffering, chelating and anti-soil redeposition action.
The materials is obtained as a thick liquid with about 45% solid content and is directly added to the mixer.
Sodium silicate helps to harden the bar when used in conjunction with either aluminium or magnesium sulphate.
10. Coconut mono ethanolamide
Earlier, up to 2% of coconut mono ethanolamide was included (CMEA) in NSD bar formulations but presently it is not being used. CMEA is a lather booster but it is very expensive.
11. Soapstock
Soapstock (SS) acts as an anti-soil redeposition agent and it was earlier used in NSD bar formulations. Currently its usage has been discontinued since controlled trials have shown that it could be dispensed with in NSD bars but not in powders.
12. Dicalcium phosphate
Dicalcium phosphate (DCP) has been used in bar formulations to the extent of upto 5% but its continued usage has not found favour because of the availability of alternative cost effective substitutes.
13. Rosin
Rosin had been used in the form of magnesium rosinate as a binder and lather booster but was not favoured in the formulation since the advantages were not commensurate with its high price.
14. Titanium dioxide
'Anatase' grade of titanium dioxide (TiO2) is used as an opacifier in detergent bar formulations and its usage varies from 0.1% to 0.3% depending on the desired end result. Titanium dioxide contributes to a bright colour by masking the colour of other ingredients by its opacifying action.
15. Colour
The most popular colour for detergent bars is blue and the colouring matter that is more commonly used is a water-dispersible blue pigment called Phthalocyanine blue.
The objective should be to produce the best results with minimum colour usage so as to prevent possibilities of staining of the fabrics during washing.
If a fluorescer (optical brightener) is used in the formulation, the blue colour must be added as the last ingredient in the mixer, since it may acquire a greenish tinge in direct contact with the fluorescer if added together.
16. Fluorescer
A common fluorescer (optical brightener) that is incorporated into the bar for fabric brightening is 'Photine C'. The level of usage varies from nil to 0.3% depending on the product desired and the cost of production. In high grade detergent bars, the fluorescer is an essential ingredient.
17. Perfume
Perfume is an important ingredient in NSD bar formulations. Its usage varies from 0.05% to 0.2% based on price considerations.
The perfume itself comprises a limited number of stable ingredients. As already stated, once incorporated, the perfume remains quite stable in an NSD bar.
18. Water
Usually water does not constitute a separate ingredient in NSD bar formulations. Water is derived from raw materials in a free and combined state, from reactions such as neutralisation of sulphonic acid or as a medium of dispersing minor ingredients such as colour.
The moisture content of an NSD bar is usually in the range of 9% to 11%.
Processing of NSD Bars
The process technology of NSD bars has undergone changes since its inception. Without going into the details of the evolutionary process changes which have given satisfactory results, the present method is described below :
Handling of Raw Materials
The raw materials can be broadly categorised as solids (powders) and liquids. The liquids are acid slurry (active detergent base), liquid caustic soda, sodium silicate, and colour solution. Acid slurry is stored in storage tanks and transferred to batch tanks located above the mixer. Liquid caustic and silicate are handled similarly. The colour solution is prepared in a small tank fitted with a stirrer and is volumetrically dispensed by a measuring mug.
Analysis of Surfactants
Most surfactants sold in the market are either pure products containing the parent compound along with some inorganic salts which are produced as such due to the very nature of their process of manufacture (and it has not been found technically or due to reasons of economics of manufacture feasible to separate the two), or formulated products. The formulated products, in general, are likely to contain more than one surfactant in their composition besides other organic and inorganic non-surfactant materials. An analysis of these products will therefore require a procedure for separation of surfactant components and non-surfactant components.
Here, in this chapter, only the analysis of surfactant components will be discussed. The method given below is used for separation of these components. It involves the extraction of anionic, cationic and non-ionic surfactants with ethanol. Inorganic, alkaline non-surfactant materials remain in the ethanol-insoluble fraction. Provision is made for the purification of the separated surfactants.
Separation of Surfactants
Weigh a sample containing 4-5 g of detergent and transfer it to a 600 ml beaker. Evaporate liquid samples containing a high percentage of water to a pasty consistency after weighing. Samples containing high levels of hydrated alkaline salts should be dried in an oven at 105oC for 1 hour after weighing. Add 300-350 ml of hot ethanol to the sample. Cover with a watch glass and heat on a steam bath for about 1½ hours, stirring frequently. Remove the beaker from the steam bath and permit the insoluble matter to settle. Add 2 drops of phenolphthalein indicator solution. If the solution is pink, neutralize with N sulfuric acid using no more than 1 ml; if necessary, use a more concentrated solution in order to remain within the 1 ml limit. Before proceeding, make the solution just alkaline with 0.1 N sodium hydroxide solution. If the solution is acid originally, neutralize with ethanolic sodium hydroxide solution to the phenolphthalein end point. Decant the ethanolic solution through a suitable filter, retaining as much as possible of the insoluble matter in the beaker. Add 50 ml of hot ethanol to the residue in the beaker and heat to boiling on a hot plate. Let the insolubilities settle and decant the ethanolic solution through the filter as before. Repeat the extraction of the insolubles with an additional 50 ml of ethanol.
Evaporate the combined filtrate to dryness on a steam bath. Add 50 ml of 1:1 acetone:ethyl ether to the residue and warm on the steam bath while stirring. Filter the solution and collect the filtrate in 50 ml beaker. Evaporate the filtrate to dryness on a steam bath and dry the residue at 105±2oC. This fraction represents the ethanol-soluble active ingredients in the sample.
IDENTIFICATION OF COMPONENTS
The isolated ethanol soluble fraction obtained by the procedure described above is dissolved in water and is subjected to tests for anionic, cationic, and non-ionics.
Anionics
To test for the presence of anionics, prepare methylene blue reagent by adding 50 g of sodium sulfate and 6.8 ml of concentrated sulfuric acid to 30 ml of 0.1 per cent methylene blue solution, and diluting to 1 litre in water. Make a 1 per cent aqueous solution of the isolated ethanol-soluble fraction. Shake 5 ml of this solution with 25 ml of the methylene blue reagent and 10 ml of chloroform. The presence of a blue colour in the chloroform layer indicates an anionic surfactant.
Cationics
Prepare bromophenol blue reagent by mixing 7.5 ml of 0.2 N sodium acetate, 93 ml of 0.2 N acetic acid, and 2 ml of 0.1 per cent ethanolic bromophenol blue solution. To 10 ml of the bromophenol blue reagent add 5 drops of the test solution. A sky blue colour indicates the presence of a cationic surfactant.
Non-ionics
If either anionic or cationic surfactants are present they must be removed prior to testing for non-ionics. This can be done as follows :
Dissolve a portion of the isolated ethanol-soluble fraction in ethanol, add a tablespoon of mixed bed ion excharge resin, and stir with a magnetic stirrer for 30 min. Filter the solution and evaporate the ethanol.
Make a 1 per cent aqueous solution of the treated ethanol soluble fraction. Add 10 ml of this solution to 10 ml of chloroform and 20 ml of ammonium hexathiocyanocobaltate reagent consisting of 200 g of ammonium thiocyanate and 30 g of cobaltous nitrate in 1 litre of water. Shake. A blue colour in the chloroform layer indicates the presence of a non-ionic surfactant.
DETERMINATION OF SURFACTANTS
Total Organic Active Ingredient
The active ingredient portion of a sample may consist of a single surfactant or a complex mixture of surfactants of various types. A useful approach measurement of the total organic active ingredient regardless of type, involves extraction with ethanol, evaporation, and weighing of the residue. Many non-surfactant materials such as sodium toluene and xylene sulfonates will be included with the active ingredient if they are present. Non-surface active ether solubles and any alkali chlorides and free alkali will also be included. Correction is made for the chloride content in the method described here.
Procedure
Weigh a sample, to the nearest 0.01 g, to correspond with levels of active ingredient prescribed here.
| Per cent Ingredient expected | Weight of sample gram |
| 10-25 |
20 |
| 25-40 |
15 |
| 40-60 |
10 |
| 60-80 |
7 |
| Over 80 |
5 |
Transfer the sample to a 600 ml beaker and follow the procedure for ethanol extraction described under 'Separation of Surfactants'. Then place the residue on a steam bath and evaporate any remaining ethanol. Stir at intervals to permit complete evaporation of the solvent. Dissolve the residue in a minimum volume of hot water, not exceeding 10 ml; heat on a steam bath to effect solution. Dilute the aqueous solution with 200 ml of hot absolute ethanol. Bring to a boil on a steam bath and filter through the previously used filter, combining the filtrate with the initial ethanolic filtrate. Wash the beaker and residue several times with hot ethanol, transferring the insolubles to the filter. Wash the insolubles in the filter with several small portions of hot ethanol. Evaporate the combined filtrate and washings to approximately 450 ml and transfer to a 500 ml volumetric flask. Cool to room temperature and dilute to volume with ethanol. Pipette 100 ml aliquot into a tared flask and evaporate to dryness on a steam bath. Place in an oven maintained at 105 ± 2oC and dry for ½ an hour period to constant weight.
Correction for Sodium Chloride Content
Pipette a suitable aliquot from the 500 ml volumetric flask into a 400 ml beaker. Evaporate to a volume of about 30 ml and dilute to 100 ml with water. Add 2 drops of methyl orange indicator solution and acidify with 1:4 nitric acid. Warm slightly, stir and add 50 ml of acetone. Follow the procedure for determination of chlorides. Calculate the per cent total organic active ingredient by subtracting the per cent sodium chloride from the per cent ethanol soluble matter.
It is at times convenient to obtain an estimation of the level of organic active ingredient by difference. This may be done by substracting the sum of the percentages of water, ethanol insolubles, petroleum ether solubles, and sodium chloride from 100 per cent. This approach may also be applied to liquid products containing alcohol and water, however, in this case the sum of the percentages of alcohol insolubles, ether solubles, and sodium chloride is substracted from the per cent solids.
ANIONIC SURFACTANTS
Preliminary Estimate of Mol. Wt.
The molecular weight of the active ingredient is required information for several of the methods to be described. The following procedure is based upon the precipitation of the detergent as an acid salt with benzidine; titration of a known weight of the purified precipitate gives a measure of the average molecular weight. The procedure is applicable to alkylarly sulfonates and fatty alcohol sulfates.
Weigh a sample containing 2.5 ± 0.5 g of alkylbenzene sulfonate or alcohol sulfate and transfer to a 250 ml beaker. Add 100 ml of hot ethanol and heat almost to boiling on a hot place or steam bath. Break up any lumps of precipitate with a stirring rod, stir well, and continue to heat 3-5 minutes. Decant and filter the supernatant ethanol through a filter paper and collect the filtrate in a 400 ml beaker. Place the beaker containing the filtrate on a steam bath and evaporate almost to dryness with the aid of a stream of a clean, dry air. Add 200 ml of water and dissolve the residue. Add 1:1 hydrochloric acid dropwise until the solution is acid to litmus paper. Add 5 per cent aqueous benzidine hydrochloride solution with stirring, until precipitation is complete. Filter the solution through a filter paper using suction and a filter cone. Wash the precipitate with water until the washings are neutral to litmus paper. Dry the precipitate with the aid of suction. Transfer the precipitate to the filter and wash several times with n-pentane. Transfer the precipitate to an evaporating dish and place in a 100oC oven until dry. Grind the precipitate to a fine powder using a mortar and pestle. Spread the ground powder over the surface of an evaporating dish and dry for 1 hr. in an oven regulated at 100oC. Accurately weigh 1.3.-1.5 g of the dried benzidine complex into a 250 ml beaker. Add 50 ml of ethanol to a separate 250 ml beaker. Place the beaker containing the dissolved complex on a titration stand; inert a continuous stirrer and pH electrodes. Carefully titrate to a pH of 8.5 using 0.1 N sodium hydroxide solution. Titrate the blank to a pH of 8.5.
Mol. Wt as sodium salt = W x 100 /(A - B)N -10
Where, W = sample weight, in g; A = volume of sodium hydroxide solution required for sample, in ml; B = volume of sodium hydroxide solution required for blank, in ml; N = normality of sodium hydroxide solution.
Titration with Cationic Surfactants
Anionic surfactants may be determined volumetrically by the widely used cationic titration procedure. The method was designed specifically for alkylaryl sulfonates and fatty alcohol sulfates, but it may be used for any anionic detergent. This procedure is based on the reaction of anionic surfactants with methylene blue to form a chloroform soluble salt, upon shaking an acidified two-phase system containing methylene blue and an anionic surfactant, which causes the displacement of methylene blue into the water layer. The end point is arbitrarily taken at the point where the colour intensities of the water and chloroform layers are equal. For maximum accuracy, the chain lengths of the alkyl sulfates or sulfonate should be no less than 12, and that of alkyl aryl sulfonates, no less than 8. Because of the empirical nature of the method, it is imperative that the dilutions and volumes used be identical both in standardization and sample analysis. If the average molecular weight of the anionic surfactant is not known it may be determined as previously described.
Analysis of Detergents
Products Formulated with Detergents
A large variety of detergent products are manufactured for special household and industrial use. The most common types are discussed here.
High-Suttsing Heavy-Duty Laundry Powders and Liquids. These products for general household laundry operations are normally formulated with 10-20% detergent base, usually alkyl aryl sulfonate or fatty alcohol sulfate, or combinations of these materials. Upto 10% sodium silicate is usually added to inhibit corrosion of washing machine parts. The major builders, added at a 35-50% level, are sodium tripolyphosphate (Na5P3O10), sodium pyrophosphate (Na4P2O7), or combinations of the two. Carboxymethyl cellulose is usually added at level of 0.5-1.0% as an antiredeposition agent. Sodium sulfate is almost always present, being a by-product derived from the base detergent. The balance of the formulation may consist of optical brighteners, perfume, chelating agents and dyes. Products of this type yield alkaline aqueous solution (pH 9-10). The liquid products contain essentially the same ingredients as the powders. Small amounts of thickeners, such as methyl cellulose, are invariably present in these liquid products.
Low-Sudsing Heavy-Duty Laundry Powders and Liquids. Anionic detergents are used to formulate this type of product; in addition small amounts of nonionic detergents are added to import controlled suds. Liquid and powder types differ mainly in their water content; however the powders may contain increased quantities of fillers, such as sodium carbonate or sodium sulfate. Both types use the same phosphate and silicate builders as described in the high-sudsing variety.
Dishwashing Products : Most liquid dishwashing products are formulated with about 50% water and between 5 and 10% alcohol. The active ingredient system is usually complex and varies widely between manufacturers. Most products contain mixture of anionic and nonionic detergents, in addition to foam builders, such as fatty acid ethanolamines. The ammonium salts of long-chain ethoxylated sulfates and alkyl aryl sulfonates are the most commonly used anionic detergents. Many products contain hydrotropes such as xylene sulfonates and small amounts of opacifiers. These products, being neutral (pH 6-7), are promoted as "safe to hands."
Automatic dishwashing formulations have shown increased sales in recent years. These products are invariably compounded with high levels of sodium carbonate, tripolyphosphate, and silicates. Levels in the range of 1-4 % nonionic detergent are incorporated. Chlorine donors are used to give the products available chlorine levels ranging from 0.5 to 1%. The pH usually varies between 10 and 12.
Window Cleaners, Floor and Wall Cleaners, and All-Purpose Liquid Detergents : This class of products in designed for hard surface cleaning and all three classifications vary widely in composition. Window cleaners are formulated with high levels of water (90%) and some contain small amounts of alcohol. Small amounts of nonionic detergent and ammonium hydroxide are usually present. Most products of this type also contain synthetic glycol derivatives such as ethylene glycol monobutyl ether. Some manufacturers offer a clear liquid, usually blue in color, dispensed in pump spray containers, others provide an aerosol foam spray.
Floor and wall cleaners are alkaline mechanical mixes of inorganic alkaline phosphates, silicates, and carbonates. Small amounts of anionic detergents, usually less than 1%, are added.
All-purpose cleaners, formulated for general household cleaning, are liquid products; many brands contain ammonia. Formulations vary between manufacturers, but they are all alkaline and invariably contain pyrophosphates and low molecular weight aryl sulfonates. Nonionil detergents are usually present.
Powdered Cleansers : Cleansers are formulated especially for use on porcelain and enamel surfaces. They contain high levels of abrasives, small amounts of phosphates, and about 1-3% anionic detergent predoninatly of the alkayl aryl sulfonate type. Practically all cleansers contain small amounts of chlorine bleach.
Detergents with Enzymes : The newest entries in the detergent market are the stain-removing enzyme detergents. Two types are currently sold: the pre-soak varieties, which are used prior to washing and rely on stain removal via enzyme action during lengthy soaking; and the regular type used in normal washing operations and relying on enzymatic stain removal during the normal wash cycle. Up to 1% enzyme is present in these products.
Laundry Bleaches : Laundry bleaches are powdered products containing bleaches in addition to small amounts of anionic detergents and phosphates. Oxygen bleaches such as potassium monopersulfate are commonly employed; however , some products contain organic chlorine-type bleaches. This type of products is in direct competition with liquid chlorine bleach, which is an alkaline solution of sodium hypochlorite.
Household Specialty Compounds : This class of products includes a huge variety of compounds designed for specific household purposes. Included are the following types; rug cleaners, oven cleaners, spot removers, scouring pads, and special detergent formulations for fine fabrics.
Toiletries : Three types of toiletries can be classified as detergents because they are formulated to remove soil; they are shampoos, dental creams, and detergent toilet bars. Shampoos empoly a wide range of anionic and nonionic detergents. Formulations vary greatly between manufacturers and the products are sold as liquids, gels, creams, and lotions. Dental creams contain less then 5 % detergent; the most commonly used types being the anionics sodium lauryl sulfate and sodium lauroyl sarcosinate. The balance of the product consists of water, abrasive, glycerol or sorbitol, and flavoring agents. Detergent toilet bars complete with soap bars and are particularly suited to hard-water areas. Several products are actually combinations formulated with soap and anionic detergents.
Industrial Detergents : This category includes a very wide range of products which are designed for special duty industrial cleaning and sold in bulk. Examples are car washes, aircraft cleaners, commercial laundry detergents, waterless hand cleaners, and drycleaning formulations.
Methods of Analysis
The methods described are generally applicable, except where noted, to both detergent bases and products formulated with detergent bases. Since the number of combinations of various surfactants in infinite, it is not possible to present a single analytical scheme which will identify and determine each one. References 5 and 8 will be found useful in solving particular problems.
Sampling
Most detergent bases are manufactured in slurry form. It is advisable to mix the slurries thoroughly with a stiff spatula or in a blender at moderate speeds, and to weigh all samples at the same time. For slurries that separate into phases quickly, representative samples can be taken while mixing, preferably with an electric stirrer. It is important in working with slurries to take precautions to prevent undue loss of water during sampling.
Liquid detergent products are usually fairly homogeneous, but should be mixed well by shaking prior to sampling. Detergent products which have been spray-dried are also fairly homogeneous. This type of product should be transferred to a tightly sealed jar before starting analysis. Spray-dried samples containing multicolored particles should be ground.
Some products, such as enzyme detergents and many industrial detergents, are mechanical mixes. They should be prepared for analysis by grinding for a short period in a blender. Care must be exercised to limit the time of grinding to minimize moisture losses. If a bulk sample of such a product is received, it should be passed through a multiple slot sampler, or riffle, to reduce the sample to a representative working amount. Such a device in shown in Figure 1. The riffle consists of a metal box mounted on legs and fitted with parallel compartments of equal width. The bottom of the compartments slopes alternately to opposite sides of the box at an angle of approximately 600 to the horizontal. The lower chutes of the sides are uncovered to permit sample discharge. Three containers are used; two are fitted on opposite sides of the box and one contains the product to be sampled. The tops of the containers are covered to minimize dusting. The product is poured uniformly into the top of the box; one half is collected in each side container. The product in one container is discarded and the operation is repeated until the total sample has been riffled. The fractions-representing half of the total sample are combined and the operation is repeated until the sample has been reduced to the requisite amount.
Separation
In order to identify the surfactants in detergent bases and products a separation scheme is necessary. The method given below is applicable for most purposes. It involves the extraction of anionic, cationic, and nonionic detergents with ethanol. Inorganic alkaline detergent remain in the ethanol-insoluble fraction. Provision in made for the purification of the separated detergent.
Procedure
Weigh a sample containing 4-5 g of detergent and transfer it to a 600-ml beaker. Evaporate liquid samples containing a high percentage of water to a pasty consistency after weighing. Samples containing high levels of hydrated alkaline salts should be dried in an oven at 1050C for 1 hr after weighing. Add 300-350 ml of hot ethanol to the sample. Cover with a watch glass and heat on a steam bath for about 1½ hr, stirring frequently. Remove the beaker from the steam bath and permit the insolubles to settle. Add 2 drops of phenolphthalein indicator solution. If the solution is pink, neutralize with N sulfuric acid using no more than 1 ml. if necessary, use a more concentrated sulfuric acid solution in order to stay within the 1-ml limit. Before proceeding, make the solution just alkaline with 0.1 N sodium hydroxide solution. If the solution is acid originally, neutralise with ethanolic sodium hydroxide solution to the phenolphthalein end point. Decant the ethanolic solution through a suitable filter, retaining as much as possible of the insoluble matter in the beaker. Collect the clear filtrate in a suitable flask or beaker. Add 50 ml of hot ethanol to the residue in the beaker and heat to boiling on a hot plate. Let the insoluble settle and decant the ethanolic solution through the filter as before. Repeat the extraction of the insoluble with an additional 50 ml of ethanol.
Evaporate the combined filtrate to dryness on a steam bath. Add 50 ml of 1:1 acetone ethyl ether to the residue and warm on the steam bath while stirring. Filter the solution and collect the filtrate in a 50-ml beaker. Evaporate the filtrate to dryness on a steam bath and dry the residue at 105 ± 20C. This fraction represents the ethanol-soluble active ingredients in the sample.
IDENTIFICATION OF COMPONENTS
Chemical Tests for Surfactants : The isolated ethanol-soluble fraction, obtained by the procedure described under Separation, is dissolved in water and subjected to tests for anionic, cationic, and nonionic detergent.
Procedures
Test for anionic Detergent : Prepare methylene blue reagent by adding 50 g of sodium sulfate and 6.8 ml of concentrated sulfuric acid to 30 ml. of 0.1% methylene blue solution, and diluting to 1 litre with water. Make a 1% aqueous solution of the isolated ethanol-soluble fraction. Shake 5 ml of this solution with 25 ml of the methylene blue reagent and 10 ml of chloroform. The presence of a blue color in the chloroform layer indicates an anionic detergent.
Test for Cationic Detergent : Prepare bromophenol blue reagent by mixing 7.5 ml. of 0.2 N sodium acetate, 93 ml of 0.2 N acetic acid, and 2 ml of 0.1% ethanolic bromophenol blue solution. To 10 ml of the bromophenol blue reagent add 5 drops of the test solution. A sky-blue color indicates the presence of a cationic detergent.
Test for Nonionic Detergents : If either anionic or cationic detergents are present they must be removed prior to testing for nonionic detergents. This can be done in the following manner: Dissolve a portion of the isolated ethanol-soluble fraction in ethanol, add a tablespoon of mixed bed ion-exchange resin, and stir with a magnetic stirrer for 30 min. Filter the solution and evaporate the ethanol.
Make a 1% aqueous solution of the treated ethanol-soluble fraction. Add 10 ml of this solution to 10 ml of chloroform and 20 ml of an ammonium hexathiocyanocobaltate reagent consisting of 200 g of ammonium thiocyanate and 30 g of cobaltous nitrate in 1 litre of water. Shake. A blue color in the chloroform layer indicates the presence of a nonionic detergent.
Other schemes for the chemical separation and identification of synthetic detergents can be found in Reference 13 and 14.
Infrared Spectroscopy. Most wet chemical schemes of qualitative examination have been superseded by infrared spectroscopy (15,16). Identification of the surfactant is based upon the presence of infrared absorption bands attributable to specific functional groups. The ethanol-soluble matter is first isolated by the procedure given under Separation. Whenever possible the infrared spectrum is obtained directly from the organic material, by forming film between salt blocks and recording the spectrum between 2 and 15 µm. The film is satisfactory if the spectrum shows 10-30% transmittance in the strongest absorption region. If the physical properties of the sample prevent direct use as a film, the spectrum may be obtained from a mineral oil mull. The mull is formed by adding 2-3 drops of mineral oil to a small quantity of sample contained in an agate mortar, and grinding for a minimum of 5 min. This should produce a very fine syrupy dispersion, which can be used as a film between salt blocks. If the sample is available in dry, powdered form, the potassium bromide pressed-disc method may be used. The sample is ground sufficiently to prevent radiation scatter, and approximately 1 part sample is added to 19 parts of dry powdered postassium bromide. The disc is formed at room temperature in vacuum, under pressure of 10-30 tons/in.2 The spectrum is recorded between 2 and 15 µm. The wavelength position of each specific absorption band is noted and the absorption bands are identified in terms of functional groups by the use of data in Table 1 or other appropriate reference sources. The types of surfactants present are identified by comparison of the characteristic functional groups with those obtained in known standards.
Gas Chromatography with Prior Desulfonation
: Desulfonation of alkyl aryl sulfonates to recover the base alkylate can be effected using phosphoric acid (19, 20). This technique may also be used for decomposing most anionic detergents into characteristic recoverable oils. It involves steam-stripping a mixture of the surfactant and phosphoric acid at 200-2150C for ½-2 hr. The procedure is given below; it is only applicable to linear alkylate-based materials.