Hemimicelle formation of cationic surfactants at the silica gel–water interface

Abstract

Based on the consideration of the thermodynamics of adsorption of surface-active ions, equations for the calculation of the hemimicelle aggregation number (n_hm), equilibrium constant (K) and the standard free energy (ΔG) of hemimicellization have been developed. By using these equations n_hm, K and ΔG° have been calculated for systems of silica gel–cationic surfactant solution with or without various additives. The results show that the adsorption mechanism and the methods proposed for the calculation of n_hm are reasonable and acceptable.