Ionic conductivity and hydrogen permeability of microporous polysulfone membranes grafted by acrylic acid

Energy losses and purity of product gases in alkaline water electrolysis strongly depend on properties of a separator positioned between the electrodes. This paper reports on heterogeneous separators based on microporous polysulfone membranes modified by graft co-polymerization of acrylic acid. After neutralization with KOH, the pores of the modified membranes were filled with potassium polyacrylate, a superabsorbent material forming hydrogel upon intake of an aqueous electrolyte. Under electrolysis conditions of 50 degrees C and atmospheric pressure, increasing amount of hydrogel in pores suppresses hydrogen permeability without apparent reduction of ionic conductivity. We have identified the product of ionic resistance and hydrogen flux as a suitable parameter to compare performance of separators of various thickness. In terms of this parameter, present separators surpass the performance of ZirfonTM Perl UTP 500 tested under the identical conditions. Ex-situ aging test in 30 wt% KOH at 60 degrees C has revealed preservation of high wettability for up to 1340 h.