Doping Sb into CuFe2O4 improved the catalytic performance in the electrochemically enhanced homogeneous peroxymonosulfate-heterogeneous catalytic system for the degradation of ciprofloxacin

Abstract

In this study, the electrochemically enhanced homogeneous-heterogeneous catalytic system (EC/Sb-CuFe2O4/PMS and EC/Sn-CuFe2O4/PMS) was constructed by placing the heterogeneous CuFe2O4-based catalyst in parallel between the anode and the cathode, which was applied to activate PMS to remove ciprofloxacin (CIP). Sb and Sn were doped into CuFe2O4 nanosheets to improve its intrinsic catalytic performance. Under the optimal conditions (3.5 mM PMS, the catalyst area of 4 × 5 cm2, natural pH and the current density of 15 mA/cm2), 90.3 % of CIP was removed by the proposed EC/Sb-CuFe2O4/PMS system, which was much higher than that of the EC/CuFe2O4/PMS (71.56 %) and EC/Sn-CuFe2O4/PMS (77.71 %) systems. The enhanced degradation performance of EC/Sb-CuFe2O4/PMS system was mainly due to the increased species and content of low-valence metal ions (beneficial to the activation reaction of PMS) and the rougher surface for the sufficient contact between the Sb-CuFe2O4 heterogeneous catalyst and the homogeneous PMS, which in return promoted the activation of PMS and generated more ·OH and SO4·- for the degradation of CIP. The generated intermediates in the degradation process were analyzed and the possible degradation pathways were proposed. The developed EC/Sb-CuFe2O4/PMS system was a potential candidate for the degradation of CIP in the environment. In addition, improving the catalytic performance of heterogeneous spinel catalysts by moderate doping also provided new opportunities to develop more efficient catalytic materials.