Insight into the electrochemical oxidation system for chlorine radical-mediated degradation of 5-fluorouracil

5-Fluorouracil (5-FU) is a widely used chemotherapeutic agent in cancer treatment, but its persistent presence in the environment poses potential hazards to ecosystems. This study systematically investigated the role of the electrochemical oxidation (EO) system for chlorine radical-mediated degradation of 5-FU. Electrodes performances, electrolysis experiments, and free radical quenching were used to examine the role of direct anodic oxidation, OH, and reactive chlorine species (RCS) in the EO of 5-FU. Based on the initial 5-FU concentration of 50 mg L −1 , current density of 7.5 mA cm −2 , and electrolysis of 20 min, the removal efficiencies of 5-FU by the Ti/RuO 2 -IrO 2 electrode were 18.38 % and 100 % in Na 2 SO 4 electrolyte and NaCl electrolyte, respectively. The enhancement of degradation effect should originate from the production of free chlorine, Cl 2 − and ClO in the anode, rather than through OH oxidation. A series of control experiments are also performed, indicating that NaCl concentrations, current density, and initial 5-FU concentrations appeared to greatly impact the degradation rate . Response surface analysis predicted the optimal operation condition at the current density of 10.02 mA cm −2 , the time of 14.79 min, and the NaCl concentration of 1.85 g L −1 . Moreover, the intermediates and dominant degradation pathways were deduced in the chlorine radical-mediated EO system. This work provided a new insight into the application of EO in addressing chlorine radical-mediated drug pollution, offering a scientific basis for wastewater treatment applications. An electrochemical oxidation system for chlorine radical-mediated degradation of 5-FU was developed with Ti/RuO 2 -IrO 2 mesh electrode, following a new insight into the role of RCS in degradation of 5-FU. • An electrochemical oxidation system for chlorine radical-mediated degradation of 5-FU was developed. • 98.7 % of 5-FU removal was achieved via Ti/RuO 2 -IrO 2 electrode in NaCl electrolyte. • Free chlorine, Cl 2 − and ClO produced in anode could removal the 5-FU. • Response surface analysis was predicted the optimal operation condition.