Enhanced mechanism of AO7 degradation by electrochemical activation of persulfate at carbon felt and electrogenerated H2O2 carbon black-modified cathodes in divided cell

Electrochemical activation of persulfate (EA-PS) is gradually drawing attention owing to its low energy consumption, environmental friendliness and good recycling performance. In this paper, carbon felt (CF) and carbon black modified carbon felt were (CB-CF) employed as cathodes in divided cell to degrade acid orange 7 (AO7), respectively. Different experimental parameters were discussed, including initial AO7 concentration, initial pH, current density and PS concentration. AO7 degradation in EA-PS process is followed the order of CB-CF>CF, owing to the in situ H₂O₂ generation at CB-CF cathode. The AO7 degradation mechanism was explored in the presence of Cl^-, PO₄^3-, HCO₃^- and HA. Quenching experiment and EPR results revealed that AO7 degradation was the comprehensive effect of ^•OH, SO₄^•- and DET in CB-CF system, while in CF system it was the comprehensive effect of ^•OH, SO₄^•-, ¹O₂ and DET. This work provides a feasible strategy for EA-PS process that producing H₂O₂ in suit for organic contaminants degradation.