Electrochemical degradation of carbamazepine-10,11-epoxide through a reactive intermediate "hypochlorite ions": A case study of monitoring the by-products using LC-TOF/MS

• EPX-CBZ impact on health & aquatic organisms in water samples. • Electrochemical oxidation as a method for EPX-CBZ removal. • Assessment of factors influencing EPX-CBZ degradation. • Identification of by-products during the electrochemical process. Carbamazepine-10,11-epoxide (EPX-CBZ) is the main by-product of carbamazepine metabolism in the liver. It has been detected in water samples and biological fluids, causing impacts on human health and aquatic organisms. It couldn't be eliminated via biological treatment methods, so the electrochemical oxidation process appears to be a great option to degrade and remediate it. Different factors, such as the initial concentration of EPX-CBZ, the applied voltage, the sodium chloride dose, and the type of matrix, were assessed during the electrochemical process of EPX-CBZ. The kinetics study and consumption energy were calculated using all selected independent factors. The efficiency of the electrochemical oxidation process was investigated using wastewater samples spiked with carbamazepine-10,11-epoxide. Furthermore, identification and elucidation of the selected by-products were performed using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). The obtained results exhibited a good view of the efficiency of the electrochemical oxidation process in the degradation of EPX-CBZ. However, all selected factors were effective in the elimination of compounds, resulting in a removal rate of up to 95 %. Energy consumption ranged between 0.15 and 0.35 Wh/mg at the end of electrolysis under the effects of independent factors. While the parent compound degraded, six by-products were detected and identified at 20 min using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). The results suggest that the electrochemical oxidation process using graphite as an anode is capable of eliminating the target compound and its by-products under selected conditions.