Electrochemical degradation of the antibiotic chloramphenicol via the combined reduction-oxidation process with Cu-Ni/graphene cathode

Abstract Chloramphenicol (CAP) still has harmful effects on the aquatic environment due to its extensive use in developing countries. The combined electrochemical reduction-oxidation process is designed to degrade CAP in a three-electrode system with Cu–Ni/graphene cathodes. The complete removal of CAP occurred within 15 min in the cathodic compartments due to the rapid reduction of the nitro group on the Cu–Ni/graphene cathode, while the removal efficiency of CAP on the anodic compartment was only 11.7 ± 1.0% after 10 min. It is noteworthy that CAP becomes more susceptible to mineralization after complete nitro conversion and dechlorination within 1 h. Under the optimal conditions, the removal rates of TOC in anodic and two cathodic compartments are 98.9 ± 0.7%, 96.6 ± 0.7% and 96.1 ± 0.8%, respectively, via combined anodic and cathodic degradation. Analysis of the detected products reveals two distinct pathways for CAP degradation in the anodic and cathodic compartments. Unlike the single oxidation step on the anode, the mineralization in the cathodic compartment after the reduction process is achieved with the support of the cathodic reduction and decomposition of O2 into oxidant products (H2O2, •O2¯, •OH). The three-electrode degradation system equipped with two Cu–Ni/graphene cathodes combines the advantages of electrochemical reduction and oxidation by varying the type of feed gas (H2 or O2). Hence, this system is also applicable to the degradation of other halogenated antibiotics in wastewater.