Micellar and associated thermodynamic properties of binary mixtures of alkyl triphenyl phosphonium bromides in ethylene glycol and water mixtures

Micellar properties of binary combinations of a family of cationic alkyl triphenyl phosphonium bromides with varying chain length (C-10-C-16) were investigated in aqueous and aqueous ethylene glycol mixtures employing conductometric technique. The results of the mixed systems were analyzed in the light of the Regular Solution Theory and the Gibbs-Duhem equation to evaluate the composition of the mixed micelle, the activity coefficients, and the interaction parameter (beta). The excess free energy and the other related thermodynamic parameters of mixing were calculated and discussed in terms of the stability of the mixed micelles in the presence of an ethylene glycol additive.