Photo-electrocatalytic degradation of remdesivir from aqueous solutions using Ni-doped ZnO nanocomposite: Kinetic, degradation pathway, toxicity reduction and reusability

Currently, there has been increasing interest in developing active photocatalysts for the treatment of wastewa-ters. In this study, Nickel (Ni)-doped Zinc oxide on a fluorine tin oxide (ZnO/FTO) was synthesized and utilized as an electrocatalyst for efficient degradation and mineralization of remdesivir (REMD). Ni-ZnO/FTO electrode was characterized using XRD, SEM, EDX, LSV, and DRS analyses. The influence of operational parameters on the degradation efficiency procedure was explored in a batch photo-reactor and their optimum values were selected. At optimized conditions (e.g. initial REMD concentration = 1 mg/L, electrolyte concentration = 0.1 g/L, current intensity = 0.03 A, and pH = 7), within 2 h under UV-A, the removal efficiency of initial REMD concentration was 92 %, whereas TOC and COD removal efficiency were found as 80.1 % and 69.5 %, respectively. The assessment of the degradation rate within 2 h indicates that REMD degradation obeyed first order kinetic model. Additionally, in the comparison of degradation and mineralization efficiency of electrolysis, photolysis and photocatalytic and photoelectrocatalysis (PECP) processes for REMD removal, PECP gave the highest efficiency. The toxicity evaluations showed that the toxicity of solutions treated by the proposed PEC process significantly decreased in comparison with untreated controls. Based on reusability investigations, Ni-ZnO/FTO can be reused for at least five repetitive times with suitable efficiency. Moreover, by taking into account all results, it was concluded that the affordability, high potentiality, and well regenerability of Ni-ZnO/FTO make it an attractive electrocatalyst in terms of drug-containing wastewater treatment.