Membrane Phenomena in Nonisothermal Systems: Part 3. Thermal Membrane Potential across Various Hydrophobic Anion-Exchange Membranes with 10 and 14% Divinylbenzene

Abstract

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 (Δψ) and the logarithmic temperature difference (Δln T) was observed. The temperature coefficient of the thermal membrane potential (Δψ/Δln 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 Tc is the constant temperature of the solution on one side of the membrane. The absolute value of Δψ/Δln T decreased with increasing the molality of the external electrolyte solutions. The absolute value of Δψ/Δln T in KCl solutions was higher than that in KIO3 solutions. For halide ions the order of the absolute values of the thermal membrane potential (Δψ) 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 Δψ was found to be NO3− > IO3− > SO42−, which is opposite to the order of the B-coefficient as well as to that of the molar volume of these hydrated ions.

Perspectives on Thermoelectric Energy Conversion in Ion-Exchange Membranes

“…Figure 2 and Figure 3 give a summary of results obtained with calomel electrodes and KCl as electrolyte with cation- and anion-exchange membranes, respectively. The observed relation was similar when other electrolytes were used [ 31 , 37 , 43 , 51 ], and the slopes were almost the same as the theoretical value 0.1984 mV/K obtained for ideal selective membranes, neglecting the effect of water transport. They were interpreted using the Tasaka expression (Equation ( 28 )).…”

“…Non-isothermal transport phenomena in charged membranes have been reported occasionally in the literature since then [ 26 , 27 , 28 , 29 ]. In the 1970s and 1980s, Tasaka and co-workers were central [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], while new researchers joined in the 1990s [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. Different aspects were studied, such as the influence of the membrane type [ 40 , 41 , 42 , 51 , 52 ], the concentration and nature of the electrolyte solutions in contact with the membrane [ 39 , 42 ], and the membrane-transported entropy of ions [ 42 , 45 ].…”