Persulfate has many uses as an oxidant in environmental applications. This research investigated electrochemical production of persulfate from mixtures of sulfuric acid and sodium sulfate using boron doped diamond film electrodes. Experiments performed in a flow-through reactor were used to determine the effect of sulfate concentration, solution pH value, and current density on the kinetics of sulfate production. Persulfate production rates were second order in sulfate concentration and second order in current density. Faradaic current efficiencies for persulfate production ranged from 12 to 98%, and were dependent on both the current density and sulfate concentration. Density functional theory simulations were used to investigate the activation energies for sulfate oxidation via direct electron transfer, and via reaction with hydroxyl radicals produced from water oxidation. DFT simulations were also used to investigate reactions leading to persulfate production from anodically produced radical species. Reactions leading to the destruction of persulfate competed with persulfate production reactions. DFT simulations were used to investigate reactions leading to acid catalyzed, base catalyzed, and heat catalyzed destruction of persulfate. In batch recirculation experiments, the ultimate fraction of sulfate that could be converted into persulfate was dependent primarily on the reaction temperature.

Electrochemical generation of persulfate using boron-doped diamond film electrodes

246th National Meeting (2013)

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