ADSORPTION OF SURFACTANTS FROM AQUEOUS SYSTEMS ONTO SOME SOLID SURFACES

Abstract

This study is divided into two main parts. The first part deals with the preparation of some monoisomeric alkylbenzene sulphonates having different alkyl chain lengths. The adsorption of these anionic surfactants onto kaolinite is studied. The second part deals with the preparation of some nonylphenol ethoxylates having different polyoxyethylene (POE) chain lengths. The adsorption of these nonionic surfactants onto kaolinte is studied, as well. Several parameters affecting the adsorption, of the employed surfaetants, are investigated.

In the first part, the sodium salts of three mOnOISOmene alkyl benzene sui phonates, having C9, C1 1 and C 12 alkylchains, are prepared. Their critical micelle concentration (CMC) are determined from the surface tension-concentration isotherms through the least-square regression analysis. Some other physico-chemical properties of these anionic surfactants are also determined.

The study reveals that a linear decrease, in CMC of the investigated sulphonates is obtained with increasing chain length whereas, changing the pH of the system has an insignificant effect on the CMC values of these sulphonates. At 30 C and in the presence of 1 .25 wt. % NaCI, 3$C9ABS,

3$CI 1ABS and 4$C12ABS are found to have CMC values of 1800, 220 and 96 )lmoles/litre. The investigated sulphonates have Krafft points of 1 8, 25 and 16 C for 3$C9ABS, 3$CJ 1ABS and 4$C 1 zABS, respectively