The influence of H2SO4 electrolyte concentration on proton transfer resistance of membrane/solution interface

The proton transfer resistance of membrane/solution interface is investigated in this paper by employing H2SO4 aqueous solution with different concentration. Two commercial cation exchange membranes, Nafion1135 and PE01 membranes with different ion exchange capacity were selected as test membranes; Proton transfer resistance measurements were made by A.C impedance techniques. The proton transfer resistance of membrane/solution interface increases quickly from 0.059 to 2.22 Ω with the decrease of H2SO4 concentration from 2.0 to 0.05 mol/L. The ion exchange capacity of the membrane, or more exactly, the surface charge of the membrane has obviously effect on the membrane/solution resistance due to the formation of electrical double layer (EDL). The effect of electrolyte concentration on membrane/solution interface resistance can be explained by the electrical interactions between ions and charged groups of the membrane: high concentration of ions in the medium can compress the EDL and reduce the electrical interactions between ions and charged groups of the membrane.