Photocatalytic degradation and dechlorination mechanism of diclofenac using heterojunction Mn-doped tungsten trioxide (Mn-WO3) nanoparticles under LED visible light from aqueous solutions

The aim of this study was to investigate the photocatalytic mineralization and degradation of Diclofenac (DCF) using Mn-WO₃/LED in a photoreactor setup. The study analyzed the impact of operational variables, such as the initial concentration of DCF, pH level, reaction time, and catalyst dosage, on the degradation of DCF in the Mn-WO₃/LED process. The characteristics of Mn-WO₃ nanoparticles (NPs) were analyzed using a variety of techniques, including BET, TEM, XRD, TGA, FTIR, and FESEM. The results showed that the optimal conditions for achieving complete degradation of DCF were a pH of 7, a reaction time of 70 min, and a photocatalyst dosage of 2.2 g/L. To assess the toxicity of DCF and its degraded products, Daphnia Magna was used for toxicity analysis. It was determined that the degradation of DCF was primarily mediated by the presence of free HO· radicals. Under optimal conditions, the degradation of DCF reached a mineralization rate of 74% within 90 min and 88% within 180 min. The presence of aqueous anions did not significantly impact the degradation of DCF, demonstrating the stability of the process. Intermediate products of the degradation of DCF included simpler compounds such as phenol and maleic acid. Toxicity analysis demonstrated a significant reduction in the toxicity of the aqueous sample after DCF degradation compared to the control, demonstrating the efficacy of the treatment process. Furthermore, the process proved to be energy efficient, with a lower energy consumption than previously reported methods. Overall, the Mn-WO₃/LED process presents itself as a promising, feasible, and cost-effective solution for the degradation and mineralization of emerging contaminants such as DCF.