Evaluation of mineralization kinetics and pathway of norfloxacin removal from water by electro-Fenton treatment

The development of antibiotic resistance in bacteria, which arises from the presence of antibiotics in wastewater systems, is one of the most important problems of human beings nowadays. In this study, the removal of norfloxacin (NFXN), a widely used antibiotic, from water was investigated by electro-Fenton method. This method combines the benefits of electrochemistry and Fenton's reaction for the electrocatalytic production of hydroxyl radical to oxidize bioresistant organic pollutants. Oxidation kinetics of NFXN has been evaluated and second order oxidation rate constant was determined as (1.34 +/- 0.03) x 10(9) M-1 s(-1). Mineralization behavior of NFXN has been examined by following total organic carbon changes during the electrolysis. A very high mineralization ratio (97.7%) for NFXN has been reached after 5 h electrolysis. This result suggests that electro-Fenton method is a very effective way to completely remove NFXN from water sources. A detailed investigation was conducted to determine the oxidation intermediates of NFXN using HPLC, LC-MS, GC-MS and IC analysis. These analyses revealed the formation of ten different aromatic oxidation intermediates, eleven short-chain substances and three inorganic ions during the mineralization of NFXN. (C) 2016 Elsevier B.V. All rights reserved.