Degradation of Cephalosporin C using MOF-derived Fe-Co bimetal in carbon cages as electro-Fenton catalyst at natural pH

Abstract

Developing high performance electrocatalysts for effective antibiotics elimination for heterogeneous electro-Fenton (Hetero-EF) process is still a challenge. This work synthesized iron/cobalt bimetallic N doped graphitic carbon cages (FexCo@NC) from ZIF-8@ZIF-67-Fe dual MOF composite for Cephalosporin C (CEP-C) degradation in the Hetero-EF system at a wide pH range. Results indicated that CEP-C degradation rate and total organic carbon (TOC) removal efficiency by Fe40Co@NC catalyst were as high as 82.45% (60 min) and 61.35% (240 min) at natural pH, respectively. The unique structure with FeCo bimetal encapsulated inside the N doped graphitic carbon cages enabled Fe40Co@NC to show excellent catalytic reactivity for H2O2 activation. The generated M (•OH) and •OH all contributed to CEP-C degradation. The synergistic effects of Co0/Co2+/Co3+ and Fe0/Fe2+/Fe3+ cycles made Fe40Co@NC catalyst to continuously activate H2O2. Moreover, Fe40Co@NC catalyst showed good stability in consecutive cycles, and could still remain excellent reactivity when applied for CEP-C degradation from the real CEP-C fermentation residue supernatant. Furthermore, a possible CEP-C degradation pathway was proposed based on the identified intermediates.