Electrochemical degradation of 5-FU using a flow reactor with BDD electrode: Comparison of two electrochemical systems

In this study, the electrochemical degradation process of 5-fluorouracil (5-FU) in aqueous media was performed using a continuous flow reactor in an undivided cell (system I), and in a divided cell with a cationic membrane (Nafion^® 424) (system II). In system I, 75% of 5-FU degradation was achieved (50 mg L⁻¹) with a applied current density j_app = 150 A m⁻², volumetric flow rate qv = 13 L h⁻¹, after 6 h of electrolysis (k_app = 0.004 min⁻¹). The removal efficiency of 5-FU was higher (95%) when the concentration was 5 mg L⁻¹ under the same conditions. Nitrates (22% of initial amount of N), fluorides (27%) and ammonium (10%) were quantified after 6 h of electrolysis. System II, 77% of 5-FU degradation was achieved (50 mg L⁻¹) after 6 h of electrolysis (k_app = 0.004 min⁻¹). The degradation rate of 5-FU was complete when the concentration was 5 mg L⁻¹ under the same conditions. Nitrates (29% of initial amount of N), fluorides (25%) and ammonium (5%) were quantified after 6 h of electrolysis. In addition, the main organic byproducts identified by mass spectroscopy were aliphatic compound with carbonyl and carboxyl functionalities. Due to, the mineralization of 5-FU with acceptable efficiency of 88% found in system II (j_app of 200 A m⁻²), this system seems to be more promising in the cytostatic drug removal. Moreover the efficiency of 5-FU removal in diluted solutions is better in system II than in system I.