Electrochemical activation of peroxydisulfate using an IrO2 electrode for the efficient degradation of acid orange 74: Mechanisms of different activation methods

Electrochemical activation of persulfate is an efficient and green technology. In this study, the differences in the pollutant degradation efficiency and peroxydisulfate (PDS) activation mechanism were compared via electrochemical activation of PDS using only an IrO 2 anode, an IrO 2 cathode, and both an IrO 2 anode and stainless steel (SS) cathode. In these methods, the degradation of acid orange (AO) 74 conformed to the pseudo-first-order kinetic degradation model. The electrochemical activation of PDS using an IrO 2 anode resulted in the highest AO 74 degradation efficiency of 81.7 % with a degradation rate constant of 0.58 h −1 . The results of radical quenching and cyclic voltammetry indicated that during the electrochemical activation of PDS using an IrO 2 anode, direct electron transfer and nonradical oxidation contributed to AO 74 degradation. Using an IrO 2 cathode, the contribution to AO 74 degradation was mainly OH, while using an IrO 2 anode and SS cathode, the contribution was the joint action of the nonradical and radical oxidation. Furthermore, during the electrochemical activation of PDS using an IrO 2 anode, the degradation rate exhibited a good linear relationship with the current density and PDS concentration. The addition of Cl − considerably enhanced AO 74 degradation.