Electrolysis of hydrogen sulfide to its constituents in a solution containing equimolar concentrations of NaOH and NariS has been carried out at 80~ In a double-compartment cell employing Nation membrane as a separator, both crystalline elemental sulfur and high-purity hydrogen have been produced at high current efficiencies. Only minimal, if any, passivation of the anode by sulfur product was observed. According to solution composition, electrolysis could result in gas evolution at the anode, passivation of the anode by sulfur deposition, or oxidation of sulfide (S 2-) or polysulfide (SZS) to sulfur oxyanions. However, in an optimized solution, electrolysis gave only anodic sulfur via bisulfide (HS-) and sulfide oxidation. Voltammetric and chronopotentiometric studies showed that sulfide, bisulfide, and polysulfide oxidation occurred at about the same potential.

An electrochemical process for the decomposition of hydrogen sulfide into its constituents in an aqueous alkaline solution is presented. It essentially consists of presaturation of an alkaline scrubber solution with H2S. Thereafter, partial neutralization of the presaturated solution provides not only the necessary mass balance for electrolysis, but also creates the optimum conditions under which passivation of the anode, as well as side chemical and electrochemical reactions, are minimized. Finally, the electrolysis stage of the process leads to precipitation of crystalline sulfur at the anode and evolution of hydrogen at the cathode. Regeneration of the alkaline solution via an osmotic effect developed during electrolysis completes the process.

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