A new approach to the electrochemical decomposition of aqueous hydrogen sulfide solution into sulfur and hydrogen gas

A new approach to the electrochemical decomposition of aqueous hydrogen sul fide solution into elemental sulfur and hydrogen gas has been proposed; thi s approach can be used to get rid of anode passivation caused by sulfur pre cipitated on the anode surface. After all sulfides, including S-2, HS and H 2S in the anodic compartment, have been mostly converted into polysulfide i ons, hydrogen sulfide gas is bubbled through the anolyte until the pH of th e solution remains approximately constant. Sulfur is removed from the react ion mixture, which is then returned to the anode compartment where the unre acted sulfides and undecomposed lower polysulfide ions continue to undergo electrolysis into polysulfide ions, and then their decomposition by H2S gas again takes place. This cyclic process will lead to a high current efficie ncy with which aqueous H2S is electrochemically decomposed into sulfur and hydrogen gas without anode passivation. Results of both equilibrium calcula tions and experiments show the viability of this new approach.