Influence of the Interface Wettability of Membranes on Electrolysis Reduction of SO2 to H2S

Abstract

Converting SO2 to H2S is an important process for sulfur recycling. In our previous study, electroreduction of SO2 to H2S was achieved by using a gas-permeable catalyst membrane. In this paper, the influence of the interface wettability of the membrane was investigated since it has a great effect on the conversion of SO2 to H2S. A 94% increase in the current density and a 189% increase in H2S flux were obtained after treating the membrane using NH3 plasma when the contact angle is 93°. A formula for H2S membrane flux was established, in which the contact angle θ and surface pH have a negative effect on H2S flux. The elevated wettability (smaller θ) increased the current density of H2S production but hindered H2S diffusion due to the increased immersion depth. The surface pH increase resulting from the current density increase had tiny effects on H2S separation.