Cyclic voltammetric technique for the determination of the critical micelle concentration of surfactants, self-diffusion coefficient of micelles, and partition coefficient of an electrochemical probe

Abstract

Critical micelle concentrations (cmc) of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC) surfactants in aqueous solution have been determined by using the cyclic voltammetric technique. (Co(en)₃)(ClO₄)₃ has been used as the redox-active electrochemical probe. The cmc values so obtained for the surfactants were found to be in good agreement with the literature values. The partition coefficient, K, of the electrochemical probe between water and surfactants in nonmicellar and micellar states was estimated using the peak current, i_p and half-wave potential, E_½ values. The self-diffusion coefficient, D_m, interaction parameter, k_f, and hydrodynamic radius of the micelles were also estimated. The results suggest that the probe is sensitive to the nature of surfactant as well as surfactant concentration.