Electrocatalytic destruction of pharmaceutical imatinib by electro-Fenton process with graphene-based cathode

Electro-Fenton (EF) process is one of the most popular electrochemical advanced oxidation processes based on in-situ generation of H2O2 and continuous electrochemical regeneration of catalyst (generally Fe2+). The cathode material is a key factor for the high yield of H2O2 production which governs process efficiency. Therefore, in this study, the oxidative degradation and mineralization of imatinib (IMA), an antineoplastic drug for cancer treatment, were investigated by EF process using a graphene modified carbon felt cathode comparatively with raw carbon felt (CF) cathode. The first time that the removal of IMA from water was investigated by EF process, same for the determination of absolute rate constant (4.56 x 10(9) M-1 s(-1)) for IMA oxidation by (OH)-O-center dot. The effects of operating parameters including catalyst concentration and applied current on the process efficiency were considered. Complete mineralization of 34.5 mg L-1 IMA was obtained at 8 h treatment with graphene modified CF cathode while only 75% TOC removal was attained with raw CF cathode under same operating conditions. Also, the formation and evolution of the carboxylic acids during oxidation process provided better performances with graphene-based CF cathode. N atoms presented in IMA were finally released to the solution as NH4+ and NO3- ions. Besides, toxicity assessment with Microtox (R) method proved the formation of intermediates more toxic than IMA during mineralization process. However, solution toxicity was totally removed at the end of treatment with graphene-based CF cathode. (C) 2019 Elsevier Ltd. All rights reserved.