Iron Anode-Mediated Activation of Persulfate

Recently, persulfate (PS) has been applied to the oxidation of organic contaminants in wastewater, groundwater, and soil. However, PS requires activation by UV light, heat, transition metal, or pH control to be useful. In particular, transition metals are able to rapidly activate PS to sulfate radical. However, it is difficult to control the concentration of transition metal solution in an environmental setting. In this study, the potential of an electrochemical reaction using an iron anode to activate PS was investigated with phenol as a model contaminant. Based on Faraday's law, Fe(II) generated by the electrochemical reaction was regularly supplied to the solution to activate PS to sulfate radical. The activation of PS was influenced by current intensity; however, excess Fe(II) decreased the oxidation rate of phenol because anodic oxidation-generated Fe(II) also scavenged sulfate radical. However, the electrochemical reaction using the iron anode could be readily controlled to supply an optimal amount of Fe(II) for activation of PS. Therefore, it is expected that this electrochemical process using an iron anode could be useful for the effective removal of phenol.