Chlorobenzene Oxidation by Electrochemical Catalysis with La Modified Ti/IrO2-Ta2O5

As a typical VOCs emitted from petrochemical industry, chlorobenzene was selected to study its removal by wet oxidation with electrochemical catalysis. Ti based IrO2-Ta2O5 electrode was used in the advanced oxidation of chlorobenzene, and Sn, Sb, Pt and La were used to modify Ti/IrO2-Ta2O5. Ti/IrO2-Ta2O5-La showed the highest removal rate of chlorobenzene and it reached 99.2% for the chlorobenzene oxidation, which was 20% higher than those of the other 3 additions. Oxygen evolution overpotential of Ti/IrO2-Ta2O5-La increased to 1.17 V when compared with Ti/IrO2-Ta2O5 of 1.08 V. EPR tests for free radicals and GC-MS tests for intermediates showed that the main active substance was ·OH, and the element Cl in chlorobenzene dissociated from the benzene ring under the action with ·OH to form ·Cl and ClO· radicals. Degradation pathway of chlorobenzene was figured out as chlorobenzene→ phenols→ organic acids→ CO2+H2O.