CATION-EXCHANGE WITH REVERSE MICELLES

Experimental and modeling studies on the extraction of K+ and Mg2+ from an aqueous phase to an organic phase using a dinonylnaphthalenesulfonic acid (HD) reverse-micellar system were conducted at 25-degrees-C. Systems containing two cations (binaries) and three cations (ternary) were investigated. Experiments for the binary systems were conducted with constant and variable total normality of cations. The system exhibited behavior similar to that of conventional ion-exchange resins. The selectivity was in the order Me2+ > H+ > K+. The distribution coefficient for Mg2+ and K+ and the molar ratio of water to surfactant in the micellar phase were independent of surfactant concentration. The solubility of HD in the aqueous phase was low. The results of the equilibrium partition experiments were correlated using a thermodynamic model. Interaction parameters determined from binary system experimental data were used to predict the ternary system partition behavior with good agreement.