Enhanced photocatalytic degradation of meloxicam and piroxicam using zeolite-supported TiO2 and ZnO nanoparticles: a comparative study of the performance and reusability of catalysts

This study investigates the photocatalytic degradation of Meloxicam (MLX) and Piroxicam (PRX) using zeolite-supported zinc oxide (ZnO) and titanium dioxide (TiO₂) nanoparticles (NPs). The morphology of the composites was characterized using SEM, FTIR, XRD and BET, and photocatalytic activity was assessed through kinetic and reusability studies. The effective factors, including pH, catalyst amount, pollution concentration and H₂O₂ percentages, on the MLX and PRX degradation were optimized using the experimental design based on the Box-Behanken design. First order kinetics was used to investigate the kinetic of the MLX and PRX degradation. The rate constant for both MLX and PRX degradation using Zeolite/ZnO NPs were 0.0277 ± 0.0038 min⁻¹ and 0.0275 ± 0.0040 min⁻¹, respectively. The rate constants using Zeolite/TiO₂ NPs were 0.0286 ± 0.0034 min⁻¹ for MLX degradation and 0.0305 ± 0.0035 min⁻¹ for PRX degradation. Besides, the calculated half-life of MLX and PRX degradation using Zeolite/ZnO NPs were 25.01 ± 0.06 min and 25.20 ± 0.08 min, respectively and using using Zeolite/TiO₂ NPs were 24.23 ± 0.07 min for MLX and 22.72 ± 0.07 min for PRX. The reusability of the synthesized photocatalysts indicated that Zeolite/ZnO NPs and Zeolite/TiO₂ NPs can be used for at least six degradation cycles without any meaningful change in their ability. Zeolite/TiO₂ NPs demonstrated superior initial activity and long-term reusability compared to Zeolite/ZnO NPs. Despite a lower synthesis cost for Zeolite/ZnO, its rapid performance decline over multiple cycles renders it less suitable for long-term applications. Based on its sustained high degradation efficiency and reusability, Zeolite/TiO₂ NPs were deemed the more effective photocatalyst for the degradation of MLX and PRX.