MOF-derived N-Co/Fe-PC composite as heterogeneous electro-Fenton catalysis combined with electrocoagulation process for enhanced degradation of Cu-CIP complexes from wastewater

Abstract

Recently, heavy metal-antibiotic complexes have been frequently detected in wastewater, posing a serious threat to the human health. In this study, a novel combination of heterogeneous electro-Fenton (hetero-EF) and electrocoagulation process was developed for efficient removal of Cu-ciprofloxacin complexes (Cu-CIP). As hetero-EF cathode catalyst, N doped porous carbon loaded with Co/Fe sites (N-Co/Fe-PC) was innovatively synthesized, and Fe/CoNC structure was formed. The homogeneous mixing of Fe3C and Co3Fe7 resulted in the electron transfer and accumulation on Fe3C, which optimized the active substance and facilitated the oxygen reduction reaction. The effects of current, electrolyte type, pH, and concentration were comprehensively investigated, and the optimum removal efficiency of Cu, CIP, and TOC were 99.69 %, 96.40 %, and 83.62 %, respectively. Besides, it revealed that ·O2– was the dominant contributor to the Cu-CIP degradation. As a result, Cu-CIP complexes were degraded into small molecules and released Cu2+ with the ring-opening demethylation of the piperazine ring, cleavage and demethylation of carboxyl group, hydroxylation of the piperazine ring, and β-cleavage reactions of cyclopropyl group. Meanwhile, they were also adsorbed by aluminum hydroxide/hydroxyl oxides especially γ-AlOOH generated from the anode and finally coprecipitated. This study will provide a novel technology and theoretical basis for enhanced degradation of heavy metal-antibiotic complexes from wastewater.