Insights into the degradation and detoxication mechanisms of aqueous capecitabine in electrochemical oxidation process

Electrocatalytic oxidation and detoxication of capecitabine (CAP) in aqueous solution were investigated with Ti/SnO2-Sb/Ce-PbO2 anode. The relative contributions of generated free radicals showed an increase in the pseudo zero order tare constants in the following order: (OH)-O-center dot (9.4%) < SO4 center dot- (24.2%) < O-2(center dot-) (53.3%). The operating parameters and solution matrixes, i.e. applied current densities, initial CAP concentrations, initial Cl- and NO3- concentrations, influencing the CAP degradation efficiency were evaluated. The kinetic rate constant of 0.1404 min(-1) was found within 7 min at current density of 10 mA cm(-2) and initial CAP concentration of 20 mg L-1, while the mineralization efficiency of 59.5%, mineralization current efficiency of 2.06%, detoxication rate to Escherichia coli of 55.5% were achieved at reaction time 90 min. The major degradation pathways of CAP were oxidation, defluorination and bond cleavage, following with the formation of carboxylic acids, NO3-, NO2-, NH4+ and F-. Electrochemical oxidation process based on Ti/SnO2-Sb/Ce-PbO2 anode is proved to be effective for elimination, mineralization and detoxication of aqueous CAP. (C) 2019 Elsevier Ltd. All rights reserved.