Effect of unstirred solution layers on the thermal membrane potential through cation-exchange membranes

The thermal membrane potential through a cation-exchange membrane has been determined under different experimental situations. In all cases, a good linear dependence between the thermal membrane potential, Delta psi, and the temperature difference, Delta T, established between both external electrolyte solutions has been observed. The value of Delta psi decreases notably when the concentration of the electrolyte solution used is increased and it also depends on the type of the cation involved, so that Delta psi decreases when the corresponding atomic number increases. The value of the temperature coefficient, Delta psi/Delta T, is notably affected by the unstirred solution layers adjoining the membrane surfaces. A theoretical model is presented to determine the influence of the temperature polarization effect on the thermal membrane potential value.