Carbamazepine degradation via solar Galvano-Fenton treatment using Mg/Cu anode/cathode system

Carbamazepine (CBZ) is an anticonvulsant pharmaceutical that enters water systems from various sources, including human excretion, and is highly resistant to photodegradation and biodegradation in conventional sewage treatment plants. The objective and main contribution of this study is to identify the operating conditions of a solar Galvano-Fenton (SGF) process for the degradation of commercial CBZ. An Mg/Cu anode/cathode system was used. The anode was placed in parallel, and the cathode was arranged in a spiral shape inside the borosilicate tube at a distance of 0.5 mm. SGF promotes the spontaneous corrosion of Mg and, hence, does not require an external electric current, which is the main advantage of this process. A cylindrical parabolic concentrator (CPC) with a 60° inclination was designed to concentrate UV sunlight. The best operating conditions were obtained through a factorial 3⁴ design: hydraulic retention time (90 min), cathode/anode area ratio (1:1), initial CBZ concentration (25 mg/L), and hydrogen peroxide concentration (500 mg/L). The best removal efficiencies achieved were 52.96% CBZ by ultraviolet-visible (UV-Vis) spectroscopy and 68.66% chemical oxygen demand (COD) with 766 kJ/L of accumulated energy. The Mg/Cu system has a bifunctional effect on the CBZ removal mechanism: first, as a catalyst to promote oxidation reactions, and second, through the complexation of Mg-(CBZ)₂. Therefore, the use of Mg instead of Fe as the anode could be a sustainable option for advanced oxidation processes.