Electro-oxidation and solar electro-oxidation of commercial carbamazepine: effect of the support electrolyte

Carbamazepine (CBZ) is an anticonvulsant pharmaceutical that is resistant to photodegradation and biodegradation in conventional wastewater treatment plants. In this research, the degradation of commercial CBZ was studied using a boron-doped diamond-Fe system in continuous flow. A response surface model was created to determine the contributions of the current intensity (0.39, 0.50, 0.75, 1.00, and 1.10 A) or current density (1.69, 2.16, 3.25, 4.33, and 4.76 mA/cm², respectively), support electrolyte (NaCl and CaCl₂), and initial CBZ concentration ([CBZ]₀) (0.1, 1.0, 5.5, 10.0, and 11.8 mg/L). The highest CBZ removal (%) was achieved with NaCl as a support electrolyte at a current intensity of 0.64 A (2.77 mA/cm²) and [CBZ]₀ of 4.5 mg/L at a neutral pH (6–7) and a treatment time of 120 min. The electro-oxidation (EO) process achieved a removal efficiency of 77.25%, whereas solar EO removed 90.77% of CBZ in the presence of ultraviolet radiation (536.37 W/m²). CBZ degradation was fitted to the Behnajady–Modirshahla–Ghanbery kinetic model with constant values of 1/m = 0.31 and 1/b = 0.93, thereby indicating the fast decomposition of CBZ. The toxicity was significantly reduced in the effluent.