An Experimental Study of Gibbs-Donnan Membrane Equilibria Across Permselective Membranes Which Involve the Ions of Strong Inorganic Electrolytes

Abstract

Abstract The Donnan membrane equilibria arising across permselective collodion matrix membranes were studied both by a static and a flow method in systems which contain only simple strong electrolytes at relatively high concentrations, up to 0.4 equiv/l. Experimental details of the flow method and its advantage in studying the ion activity behavior are presented. From the measurements of equilibrium concentrations and Donnan membrane potentials the ratios of ion activity coefficients were calculated for the following pairs of electrolytes in mixed solutions: sodium chloride–sodium nitrate, sodium sulfate–ammonium sulfate, potassium oxalate–ammonium sulfate, and potassium oxalate–ammonium oxalate. The experiments prove the feasibility of determining the ratios of ion activity coefficients in mixed solutions at concentrations where other methods lose their usefulness.