ANALYSIS OF INTERMOLECULAR INTERACTIONS IN MIXED ADSORPTION LAYERS OF SURFACTANTS

Abstract

The adsorption of the surfactants mixtures of different chemical nature such as Triton X-100 and sodium hexadecyl sulfate at the surface of graphitized carbon black was studied. Using the model of phase separation (the Rubi–Rosen approach), the composition of the mixed adsorption layers and parameters of interaction between the surfactant molecules in the adsorption layers were calculated. It was found that mixed adsorption layers are enriched with molecules of the non-ionic surfactant Triton X-100.
 The purpose of the work was to study the adsorption of binary mixtures of surfactants of various chemical nature on the surface of non-porous hydrophobic carbon sorbent at different SAS ratio in mixtures.
 The results of calculations show that the composition of the adsorption layer on the surface of the GC is significantly different from the ratio of surfactants in the solution. The value of the parameter χ indicates that the mixed adsorption layer on the surface of the GC is enriched with non-ionic surfactant molecules, even with a small its content in the solution (αTХ-100 = 0,2). With an increase in the ТХ-100 molar fraction in the binary solution from 0,2 to 0,8 its share in the adsorption layer increases in approximately 1.5 times. Negative values of the interaction parameters βs indicate excessive attraction of the molecules and ions of the mixture components in the mixed adsorption layers. An increase in the absolute value of the parameter βs with an increase in αTХ-100 in the solution characterizes the enhancement of the interactions between the components in the adsorption layer.
 Thus, in the course of experiments carried out for mixed systems of SHDS-ТХ-100, the existence of a synergistic effect in relation to an increase in the adsorption of surfactants on the GC surface was established. It is found that mixed adsorption layers are enriched with molecules of the non-ionic surface active substance of the triton X-100.