Heat-assisted Photocatalytic Degradation of Pharmaceutical Wastewater Using TiO2–ZnO Nanocomposites: Response Surface Optimization and Performance Evaluation

Active pharmaceutical ingredients are also persistent and are not completely removed and as such pose a continuous threat to aquatic ecosystems when pharmaceutical wastes are released into water. Recently a heat-assisted photocatalytic treatment of TiO2-ZnO nanocomposites has been studied and explored in the degradation of paracetamol which is one of the most common detected pharmaceutical contaminants. The nanocomposite was prepared by a sol- gel method and characterized by XRD, SEM, BET, FTIR, and UV-vis DRS structural analysis, the resulting result of high surfaces area 56.2 m2/g, narrow band gap 2.84 eV, advanced light harvesting, and charge separation. Broad process parameters under consideration of pH [3-8] Catalyst dosage (0.3-1.5 g/L) irradiation time (15-75 min) and temperature (30-60°C) were optimized in the experiment by photocatalytic reaction carried out in a heat-integrated batch reactor under visible light irradiation with Response Surface Methodology (RSM) based on a Box-Behnken design. The maximum degradation efficiency of the system was 94.8 % at optimum pH 5.8, optimum dosage of the catalyst 0.9 g/L, and optimum time of irradiation 55minutes and a temperature of 50°C. The kinetic investigation revealed the first- order type of behaviour and the rate constant value is 0.041 min-1 and the statistical confirmation provided a R2 of 0.985 that indicates a superior model fit. The findings highlight the strong potential of this approach for long-term treatment of persistent pollutants in wastewater treatment technologies.