Metal polyphenol network structure regulated Fe2O3-CeO2/PC for the enhanced electro-Fenton-like remediation of organic wastewater in a widely applicable pH range

Abstract

Developing efficient Fenton and Fenton-like systems for the remediation of organic wastewater remains a challenge for the limited applicable pH range and sluggish kinetics. In this study, a novel electro-Fenton-like system was constructed for the efficient degradation of multiple organic pollutants based on Fe-Ce bimetallic oxide supported on porous carbon (Fe2O3-CeO2/PC) heterogeneous catalyst, which was prepared by annealing metal polyphenol network structure (MPNs) regulated Fe-Ce-tannic acid (TA) complexes. The Fe2O3-CeO2/PC-based system showed higher removal rate (93.6 %) and apparent rate constant (0.021 min−1) for tetracycline (TC) as compared to the MPNs-free Fe2O3-CeO2 system (79.1 %, 0.011 min−1), catalyst-free system (59.3 %, 0.007 min−1) and adsorption system (66.7 %, 0.009 min−1). Under the optimal conditions, the as-proposed electro-Fenton system showed a high removal rate of ∼ 95 % to the typical phenol, dye and antibiotics. After 240 min’ electrolysis, the removal rates of COD and TOC reached 93.7 % and 58.7 %, respectively. After 5 cycles’ degradation, the removal rate of TC didn’t show obvious decline in performance (remained at about ∼ 90 %). More importantly, the system can effectively remove TC in simulated wastewater in a broad pH range of 3–11, which was much superior to the other electro-Fenton-like systems. The satisfactory degradation performance of the electro-Fenton-like system based on MPNs-regulated Fe2O3-CeO2/PC was attributed to the strong coordination ability between TA and the metal species in the heterogeneous catalyst and the bimetallic synergistic effect on optimizing the electronic configuration of Fe2O3-CeO2/PC, which accelerated the redox cycles of ≡TA-Fe(Ⅲ)/≡TA-Fe(II) and ≡TA-Ce(Ⅳ)/≡TA-Ce(III) as electron shuttles and facilitated the production of sufficient ROS (mainly O2·− and 1O2) for the degradation and mineralization of the organic pollutants. Based on the produced intermediates, the feasible degradation pathways of the representative TC occurred in Fe2O3-CeO2/PC-based electro-Fenton-like system were inferred. This work lays an important theoretical foundation for the rational design of high-performance electrocatalysts and electro-Fenton/electro-Fenton-like systems, enabling the efficient remediation of organic wastewater.