Comparative study of catalytic oxidation performance of Ni-Co/Al 2 O 3 and Ni-Co/SiO 2 catalysts for real pharmaceutical wastewater treatment: process optimisation using box–behnken design and kinetic study

This study investigates the comparative catalytic oxidative performance of Ni-Co/Al2O3 and Ni-Co/SiO2 catalysts synthesised by wet impregnation method to treat real pharmaceutical wastewater. Synthesised catalysts were characterised by analytical techniques such as BET, XRD, SEM and FTIR. In addition, a box – behnken design (BBD) of response surface methodology (RSM) was implemented to optimise relevant parameters of the catalyst process: pH (3–9), catalyst dosage (0.1–0.5 g/L) and time (30–90 min) were the input variables of interest, while the response variable measured was COD removal efficiency (%). Optimal experimental conditions were determined to be pH ~ 5.9, catalyst dosage ~0.34 g/L, and reaction time ~83 min, leading to maximum COD degradation of 76.76% & 69.03% using Ni-Co/Al2O3 and Ni-Co/SiO2 catalysts respectively. Kinetics suggested that degradation was a pseudo-first-order reaction with rate constants suggesting better degradation pathways for Ni-Co/Al2O3 than Ni-Co/SiO2. Therefore, results suggest Ni-Co/Al2O3 can be an effective heterogeneous catalyst for AOP-based degradation of pharmaceutical wastewater in the future while BBD is validated as a reliable process optimisation tool to meet maximum efficiencies.