Ion-exchange equilibria for [Au(CN)(2)](-)/Cl-,[Au(CN)(2)](-)/SCN-, and SCN-/Cl- in acetone plus water mixtures at 303 K

摘要

Ion-exchange equilibria are presented for [Au(CN)(2)](-)/Cl-, [Au(CN)(2)](-)/SCN-, and SCN-/Cl- in acetone + water mixtures at 303 K using Purolite A500 as the ion exchanger. The effect of the composition of acetone in the external solution on the ion-exchange isotherm for each binary system is considered. The experimental data are correlated using the law of mass action, modified with activity coefficients, to determine the equilibrium constant for each binary system. It is shown that the selectivity of Purolite A500 is highly dependent on the composition of the external solution. The selectivity of the resin for [Au(CN)(2)](-), in particular, decreases markedly with an increase in the composition of acetone. The fitted values of the equilibrium constants are consistent with the trends observed in the corresponding ion-exchange isotherms.