Membrane phenomena in nonisothermal systems: Part 3. Thermal membrane potential across various hydrophobic anion-exchange membranes with 10 and 14% divinylbenzene

The thermal membrane potential across anion-exchange membranes having various hydrophobic anion-exchange groups was measured for various electrolyte solutions. A good linear relationship between the thermal membrane potential (Delta psi) and the logarithmic temperature difference (Delta ln T) was observed. The temperature coefficient of the thermal membrane potential (Delta psi/Delta ln T) was found to be a function of the logarithmic activities of ions with a slope of RTc/F for 1-1 electrolytes and RTc/(2F) for 1-2 electrolytes, where T-c is the constant temperature of the solution on one side of the membrane. The absolute value of Delta psi/Delta ln T decreased with increasing the molality of the external electrolyte solutions. The absolute value of Delta psi/Delta ln T in KCI solutions was higher than that in KIO3 solutions. For halide ions the order of the absolute values of the thermal membrane potential (Delta psi) was Cl- > Br- > I-, which corresponds to the order of the values of the B-coefficient in the Jones-Dole expression for the viscosity of the solutions, but opposite to that of the conventional partial molar volume. For large oxoanions the order of the absolute values of Delta psi was found to be NO3- > IO3- > SO(4)(2-)which is opposite to the order of the B-coefficient as well as to that of the molar volume of these hydrated ions.