Improved electro-assisted adsorption of anticancer drug 5-fluorouracil and its subsequent anodic degradation with synchronized electro reactivation of activated carbon electrodes
摘要
5-Fluorouracil (5-FU) is among the chemotherapeutic drugs considered emerging contaminants, highly water-soluble, persistent, and mobile organic compounds (PMOCs) detected in water bodies, which have harmful and cytotoxic effect on aquatic biota. Its high hydrophilicity causes conventional water treatment processes, including adsorption, to exhibit low efficiencies of its removal. The novelty of this work lies in the study of the electroadsorption behavior of 5-FU on commercial granular activated carbon used as a packed working electrode in a three-electrode asymmetrical electrochemical cell, as a viable option for its removal from water. The polarization of electrodes was carried out at a controlled potential in a range from 0.3 to 0.9 V vs. Ag/AgCl, which favored an increase in adsorption capacity with the highest removal of 42% vs. 13% with no polarization, and an increase of the initial adsorption rate from 0.0018 at OCP to 0.0035 mg 5-FU min−1 L−1 at 0.9 V. This occurred even if 5-FU is a nonionic molecule (at neutral pH). Its electroactive nature makes it electrochemically oxidized on the adsorbent electrode at 1 V vs. Ag/AgCl, after the electroassisted adsorption process and its degradation mechanism were studied by liquid chromatography-ion trap mass spectrometer. The electrochemical oxidation mechanism was mediated by OH anions, causing the rupture of pyrimidine rings and loss of fluoride. This oxidation allowed the electrode reactivation with a maximum of 70 ± 1.3% of removal.