Use of a Surfactant Coacervate Phase To Extract Chlorinated Aliphatic Compounds from Water:  Extraction of Chlorinated Ethanes and Quantitative Comparison to Solubilization in Micelles

Abstract

At temperatures above the cloud point, aqueous solutions of nonionic surfactants separate into a coacervate phase and a dilute phase. The distribution of di-, tri-, and tetrachloroethanes between these phases was shown to increasingly favor the coacervate phase as the hydrophobicity (degree of chlorination) of the solute increases. The solute solubilization equilibrium constant was shown to be very similar for solubilization into coacervate surfactant aggregates compared to micellar solubilization per aggregated surfactant molecule for octylphenol polyethoxylate surfactants and to increase with increasing temperature and increasing solute hydrophobicity. As temperature increases above the cloud point, the partition ratio increases primarily because the concentration of surfactant in the coacervate increases, second because the solubilization equilibrium constant in the coacervate surfactant aggregate increases, and third because the concentration of micellized surfactant (and solubilization therein) in the dilute phase decreases.