Evaluation of the Effects of Reaction Temperature and Optimization of the Conditions for the Electrochemical Conversion of Sulfate to Persulfate

Persulfate is a potent oxidizing agent extensively used as a radical polymerization initiator, bleaching agent, and water treatment agent. Typically, persulfate is synthesized via electrochemical oxidation of sulfate. However, this process is accompanied by Joule heating, which can reduce the efficiency because persulfate is susceptible to activation and decomposition by heat. The precise effect of temperature on electrochemical persulfate production has not been well understood. This study evaluated the effect of temperature on the electrochemical production of persulfate using an H-type water jacket reactor, with reaction temperature set at 15^oC, 25^oC, 35^oC, 45^oC, and without temperature control. The results indicated that higher temperatures increased persulfate decomposition, whereas uncontrolled temperature conditions yielded very little persulfate (less than 5% conversion). Notably, production and current efficiency declined sharply above 30 ℃, with the production rate at 35^oC being 2.57 times lower than at 25^oC. Moreover, maintaining a low reaction temperature increased the resistance and reduced the energy efficiency. These results underscore the necessity of temperature control for efficient persulfate production, suggesting that a reaction temperature below 25^oC is optimal for electrochemical persulfate synthesis.