Application of the Fenton and photo-Fenton processes in pharmaceutical removal: New perspectives in environmental protection

Micropollutants are detected in all elements of the environment. Among them, pharmaceuticals are a large group. Advanced oxidation processes are a promising solution for their removal. In this study, the simultaneous removal of four pharmaceuticals (ibuprofen, diclofenac, carbamazepine, and sulfamethoxazole) from aqueous solutions was investigated using the Fenton and photo-Fenton processes. The experimental design used a "one-variable-at-a-time" approach to optimise key operating parameters, including exposure time, pH, hydrogen peroxide dosage, Fe²⁺ source, and H₂O₂:Fe²⁺ ratio. A batch reactor setup was used for all experiments. Optimal removal efficiencies were achieved at pH three and a H₂O₂ dosage of 7.3 mL/L. Photo-Fenton consistently outperformed the Fenton process, achieving complete degradation of sulfamethoxazole, carbamazepine, and ibuprofen within 10 min under optimised conditions. At lower ratios of H₂O₂ to Fe²⁺ (10:1, 20:1), removal efficiency approaches nearly 100 % for all pharmaceuticals when using FeSO₄·7H₂O. In contrast, the iron nanoparticles show reduced efficacy at these ratios. However, at higher ratios (25:1, 50:1, 75:1), the efficiency of reactions FeSO₄·7H₂O decreases and becomes comparable to that achieved with iron nanoparticles. These results highlight the potential of Fenton-based processes, combined with UV radiation and optimised reagent conditions, for the effective removal of pharmaceuticals from wastewater, paving the way for sustainable environmental remediation applications.