Photocatalytic efficacy of supported tetrazine on MgZnO nanoparticles for the heterogeneous photodegradation of methylene blue and ciprofloxacin

Abstract

MgZnO@SiO₂-tetrazine nanoparticles were synthesized and their photocatalytic efficiency was demonstrated in the decomposition of ciprofloxacin and methylene blue (MB). This new heterogeneous nanocatalyst was characterized by FT-IR, XRD, UV-vis, DRS, FE-SEM, ICP, and CHN. Distinctive variables including photocatalyst dose, pH, and degradation time were investigated. Up to 95% photodegradation was gained under the optimum conditions (20 mg photocatalyst, 3.5 ppm MB, pH 9) by using MgZnO@SiO₂-tetrazine nanoparticles after 20 min. An elementary kinetic study was carried out, and a pseudo-first-order kinetic with a reasonably high rate-constant (0.068 min⁻¹) was derived for the MB decay. Photoluminescence (PL) studies confirmed that the photocatalytic activity of MgZnO@SiO₂-tetrazine was almost consistent with the Taugh plots. Thus, it can be envisaged that the photocatalytic activity is closely related to the optical absorption. Furthermore, a photoreduction mechanism was suggested for the degradation process. Addition of scavengers and some mechanistic studies also revealed that O₂˙⁻ is the original radical accounting for the degradation of MB, considering this latter compound as a model type pollutant. Finally, efficacy of the present photocatalytic process was assessed in the degradation of ciprofloxacin as a model drug under the optimum reaction conditions.