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Development of surface active agents, using naturally occuring phenols from Cashew Nut Shell Liquid (CNSL) by sulfonation.


cashew nut shell oil (CNSL) is traditionally obtained as a byproduct during isolation of cashew by roasting the raw nuts. The crude CNSL represents one of the major and cheapest sources of naturally occuring non isoprenoid phenolic lipids.
Composition: CNSL contains about
  Anacardic acid           --  82 [+ or -] 1.06%
  Anacardonol or cardanol  --  13.8 [+ or -] 0.79%
  2 methyl cardol          --  2.6 + 0.16%
  Cardol                   --  1.6 [+ or -] 0.17%


[C.sub.15][H.sub.31-n]--Unsaturated side chain with one or two or sometimes three double bonds. The substituent chain present in Anacardic acid, cardol and cardanol is not a homogeneous, diolefin but is a mixture of olefins of different degree of unsaturation.

Crude CNSL is distilled to get cardanol by the decarboxylation of Anacardic acid at 135-140[degrees]C to get commercial CNSL it contains 60-70% of cardanol and 10-15% of cardol and 15-30% of polymeric residol (residol is separated)

The structure of cardanol is similar to dodecyl benzene in the aromatic and the hydrocarbon side chain. Cardanol possess a typical lipid structure with a hydrocarbon, hydrophobic group and a phenolic end group. Most of the detergent industries make use of anionic surfactant i.e., sodium dodecyl bezene sulfonate. Therefore it was expected that the sulfonation of commercial CNSL will give a good surface acting agent like that obtained from dodecyl benzene. Hence, this research work includes preparation of surfactant from cardanol. The sulfonation reaction was carried out using conc. [H.sub.2]S[O.sub.4] at different parameters such as temperature, reaction time, mixing, retention time and salt formation. The physico chemical properties were studied such as IR absorption spectra, solubility, surface tension, HLB value etc.,

Different salts are obtained like sodium, potassium, ammonium, and calcium and ethanol amine. Sodium and ammonium salts are found to be good penetrating aids in Kraft pulping to increase the rate of delignification.

By socio economic concern and ISO 14001(3R) Reduce, Recycle, Reuse the waste generated from industries is to be converted into valuable products. On the above concept cashew nut shell oil was expelled from raw cashew nuts which is distilled and sulfonated to get a surfactant which finds valuable applications in pulp and paper, leather, insecticides and detergent industries.


Cardanol was procured from cashiotron Resins Pvt Ltd, Gundbala, Ankola (From Dr R. G. Nayak) and the properties were been studied in the laboratory. CNSL was sulfonated, different salts were prepared and their properties were studied, Following are the details of the properties of CSNL.

Sulfonation of CNSL

In acid sulfonation, the process variables are decisive for the quality of the product.

The reaction is carried out in glass vessels with glass rod or anchor type agitator (of about 120 rpm). The optimum temperature maintained during the reaction by cooling with ice. Water is added in the form of crushed ice, under no circumstance the temperature should exceed 10[degrees]C.

5 grams of cardanol is taken in a 100 ml beaker, concentrated H2SO4 is added from a burette drop wise with vigorous stirring. After adding H2SO4 the whole mass is kept agitated for another 10-15 minutes at the same temperature. The product obtained is thick mass and it is kept for 30 minutes retention time. After 30 minutes the sulfonated product is washed with about 10-20 ml of water to remove unreacted acid. Final product obtained after washing is a smooth shampoo like silky mass highly soluble in water. The solution gives soapy smell.

Preparation of salts

Various salts are prepared from sulfonated product carefully at a temperature between 0-10[degrees]C by using appropriate basic solutions as shown in the table.

Required base in a calculated quantity is added to the sulfonated product and mixed slowly with continuous stirring till pH of the solution of the product is above 8. The mixture is kept overnight and pH is again measured if the pH decreases some more amount of base is added. Other dissolved reaction products (Soluble) settle down at the bottom of the beaker are separated by using separating funnel.

Properties of sulfonated CNSL compounds

Detection of surface active agent: it was done by the Dye solubilisation technique of Hoyt with brilliant blue BMA(dialkylamine anthraquinone dye) the test indicated the presence of the surfactant.

Solubility: The solubility of sulfonated CNSL was studied in water and organic solvents, at 25[degrees]C in 100 gm of solvent

Surface tension

Measured by using stalagnometer and 10% solutions of the sulfonated Cardanol salts results are as follows:
Table 5

Sl. No   Salts               Surface tension of 10%
                             solution of salts in dynes/cm

1        Sodium salt         34.94
2        Ammonium salt       36.23
3        Potassium salt      39.99
4        Calcium salt        44.00
5        Ethanolamine salt   46.20

Test for functional group: it was done for aromatic sulfonates using diazonium salt (coupling reaction). A red dye was observed indicating the presence of sulfonated benzene derivative.

Determination of acid number: it was determined by titrating with standard 0.1N KOH (alcoholic) solution. The value was found to be maximum 8.

Determination of iodine number: it was determined by titrating with wij's' solution (iodine monochloride). The value was found in between 180-200.

HLB value: a rough estimate of HLB can be made from water solubility of the emulsifier and its dispersibility, on this basis HLB value was found in between 10-13.

Infrared spectra of sulfonated CNSL


Results and discussions

sulfonated salts of cardanol are non-ionic surfactants and belong to the category of metal salts of sulfonated alkyl phenols i.e. class II, B2.1.4.

Dye solubilisation test confirms the presence of surfactants. Functional group test, decrease in iodine number, increase in acid number and IR spectra confirms the sulfonation on the benzene ring (probably at ortho and para positions). The surfactant properties are further confirmed by solubility test, surface tension data and HLB value.


The ammonium and sodium salts of sulfonated CNSL were used to carry out experiments in craft pulping process and are proved to be good penetrating aids. They increase the rate of delignification and thus help in the reduction of use of chemicals, improves quantity and quality of pulp. Furthermore application studies are in progress related to pulp and paper industry and other fields.

Sulfonated CNSL salts can be produced on industrial scale because its preparation involves no complicated steps and gives good yield.

The research work offers a vital opportunity to explore the possibility of converting CNSL to an important surface active agent, which can be conveniently used for important applications. Such as detergents, emulsifying, penetrating, wetting and solubilizing agent.


I acknowledge with gratitude the co-operation and guidance extended to me by my Research Guide Dr. K. VasantaKumar Pai, Department of Industrial Chemistry, Kuvempu University, Shimoga.

I express the deep sense of gratitude to the Joint Secretary and Head SWRO, UGC, Bangalore for sanctioning the minor research project under X Plan period.

I extend my respectful thanks to the College Management and Shri N.G. Sabhahit, Advisor, DES Dandeli for their support and co- operation.

I take the opportunity to thank Dr. H. Y Merwade (Prof. in Chemistry) and Dr. Anita Nair (HOD, Pulp and Paper) for their advice and valuable suggestions. I wish to express my thanks to Smt. Savita Dube for her assistance and help.

I express my sincere thanks to Dr. R.G. Nayak M.D., M/s Cashiotron Resins Ltd., for providing raw material, guidance and help.


[1] John, H., Chemiker--2tg., 57, 383--4 (1933)

[2] Harris, J.C., and R. Bernstein, Bibliographical Abstracts of methods of analysis of synthetic detergents, 1888--1956, ASTM Special Technical Publication No 150A (1956)

[3] Hoyt, L.F., J. Am. oil chemist's Soc., 24, 54-6 (1947)

[4] Rosen, M.J., and G.C Gold finger Anal. chem., 28, 1979(1956)Shriner, R.L., R.C Fuson, and D.Y Cutin, Systematic Identification of Organic Compounds 4th ed; wiely NewYork P.P 55- 6;/1956

[5] Am. Soc. Testing materials, ASTM standard D 855-56. Philadelphia, Pa.

[6] 'surfactants--a global perspective' chemical weekly august 11 ; 1998

[7] Systematic analysis of Surface-active agents By Milton J. Rosen and Henry A. Goldsmith

[8] Maria Lucilia dos Santos, and Gouvan C. de Magathaes J. Braz. Chem. Soc., vol 10, No-1, 13-20, 1999.

[9] Book on "Surface active agents "by Schwartz and Perry.

[10] "Unit processes in Organic Synthesis" by P.H. Groggins, Fifth edition, Tata Mc-Graw Hill publisher.

(1) Shobha Sharma, (2) Anita Nair and (3) K.V. Pai

(1) SGL Chemistry, BN Degree College Dandeli, India

(2) HOD, P.P.Sc. Dept. BN Degree College Dandeli, india

(3) Dept. Of Industrial Chemistry, Kuvempu University, Jnana Sahydri, Shankaraghatta, Shimoga, India
Table 1: Properties of Cardanol.

Sl. No.               Particular                 Grades

1.        Colour                               Dark brown
2.        Moisture content %                   0.001-0.005
3         pH                                   5.68
4         Non volatile matter %                83-85
5         Specific gravity at 25 [degrees]C    0.927-0.94
6         Refractive index                     1.51-1.52
7         Viscosity at 300 C (Centipoises)     45-65
8         Ash content                          Negligible
9         Acid value (ml)                      Max 5
10        Iodine value (wij's method)ml        210-260
11        Hydroxyl value (ml)                  180-200

Table 2: Process variables.

1)   Acid strength              Conc. [H.sub.2]S[O.sub.4]
                                (Specific gravity 1.84) AR grade
                                from Ranbaxy Fine Chemicals Ltd.,
2)   CNSL                       Procured from local manufacturer
                                M/s Cashiotron Resins Ltd.,
                                Gundbala, Ankola
3)   CNSL: acid ratio           5:0.9 ml
4)   Sulfonation Temperature    0-100C
5)   Time of addition of acid   10 minutes
6)   Retention time             30 minutes

Table 3

Sl No   Name of the Salt          Concentration

1       Sodium Salt         10% NaOH Solution
2       Ammonium Salt       1:1 N[H.sub.3] Solution
3       Potassium Salt      8% KOH Solution
4       Calcium Salt        Saturated lime Solution
5       Ethanolamine Salt   1:1 ethanol amine solution

Table 4

Solubility     Gm/100 Gm of solvent

In Water       20-30
In Toluene     3-5
In a Butanol   4-6
In Xylene      3-5
In Acetone     Insoluble
In Benzene     4-5

Table 6: I.R. Absorption Data:

functional groups                         Wave numbers ([cm.sup.-1])

O-H of water                              ~ 3617, 3443
O-H of S[O.sub.3]H                        ~ 2934
O-H Stretching of S[O.sub.3]H             ~ 2852
O-H Stretching of S[O.sub.3]H             ~ 2361 (less intensive peak)
Aromatic C-H                              ~ 2070
-C=C-                                     ~ 1633
C-H bending                               ~ 1459
RS[O.sub.3.sup.-] Symmetric stretching    ~ 1107,1208
S=O stretching of S[O.sub.3]H             ~ 695, 617
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Author:Sharma, Shobha; Nair, Anita; Pai, K.V.
Publication:International Journal of Applied Chemistry
Article Type:Report
Geographic Code:9INDI
Date:May 1, 2010
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