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 electro-chemical activation of PDS using only an IrO2 anode, an IrO2 cathode, and both an IrO2 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 IrO2 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 IrO2 anode, direct electron transfer and nonradical oxidation contributed to AO 74 degradation. Using an IrO2 cathode, the contribution to AO 74 degradation was mainly center dot OH, while using an IrO2 anode and SS cathode, the contribution was the joint action of the nonradical and radical oxidation. Furthermore, during the electro-chemical activation of PDS using an IrO2 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.

Automated summary

Electrochemical activation of persulfate is an efficient and green technology for pollutant degradation. In this study, different methods were compared for peroxydisulfate (PDS) activation and pollutant degradation efficiency. The results showed that the electrochemical activation of PDS using an IrO2 anode had the highest degradation efficiency.