Comparative studies on the conductances and energetics of transport of aqueous solutions of alkali chlorides through microporous membranes without and with control of pores using potassium salt precipitates

Abstract

Comparative studies on the conductances of some common chloride solutions through microporous membranes, without and with control of pores by impregnating them with a precipitate of potassium zinc ferrocyanide, are reported. The microporous membranes are prepared from ion-exchange membranes of the “Neosepta” family treated with 6% H 2O 2; solution. The concentration range of the bathing chloride solutions is from 1 to 500 mol m −3. The temperature range studied is between 298 and 323 K at 5 K intervals. Both membranes have the tendency to show a smooth increase in conductance at all concentrations, tending towards a limiting value, and to maintain the order, K + > NH 4 + > Na + > Li + indicating that the proportionate hydrated sizes shown in aqueous solution are retained within the pores. The variations of conductance with temperature are utilised for the calculation of Arrhenius activation energies. These increase in the order, K + < NH 4 + < Na + < Li + parallel to their hydrated sizes, but with some variations in the case of membranes with precipitate.