Preparation of zirconium phosphate (ZrP)/Nafion1135 composite membrane and H+/VO2+ transfer property investigation

The zirconium phosphate (ZrP)/Nafion1135 composite membranes were prepared by impregnating method and characterized by SEM, XRD, ac impedance and electron probe microanalysis (EPMA) techniques. The results show that ZrP(α-Zr(HPO4)2·H2O) deposited both on Nafion1135 membrane surface and in its inner structure, and the amount of deposited ZrP increases with the immersion time. A test of membrane resistance shows that the membrane resistance increases with the immersion time greatly in CVO2+:CH+CVO2+:CH+ = 0.009:0.1 mol L−1 H2SO4 + VOSO4 solution than in 0.05 mol L−1 H2SO4 solution. Subsequently, the proton diffusion coefficient D¯H+ and VO2+ diffusion coefficient D¯VO2+ in membrane are evaluated. It is found that both D¯H+ and D¯VO2+ decrease with the immersion time based on the retarding effect of the deposited ZrP.The proton diffusion coefficient in Nafion1135 was determined to be 3.412 × 10−12 m2 s−1, and a slightly lower value of 2.827 × 10−12 m2 s−1 was found in Nafion1135/ZrP5 membrane.However, the VO2+ diffusion coefficient D¯VO2+ of the Nafion1135 membrane, 4.012 × 10−13 m2 s−1, is much higher than that of 1135/ZrP5 composite membrane, 0.3226 × 10−13 m2 s−1. The results show that the composite membrane has better permselectivity as to H+ and VO2+ than Nafion®1135 membrane.