Assessing the efficacy of semiconductor photocatalysts by utilizing photocatalytic parameters for wastewater treatment – a kinetic study

Water stress is a significant concern as many cities worldwide face a rapidly depleting potable water supply. The prevailing water emergency requires a conscious effort to treat wastewater (WW) for reuse. The greatest challenge to accomplishing adequate WW remediation is maximising the overall efficiency of wastewater treatment (WWT) systems. If a suitable photocatalyst is considered, advanced oxidation processes (AOPs) possess major prospects in WWT settings. This study aimed to evaluate the performance of various semiconductor photocatalysts for treating municipal WW. The photocatalysts considered were titanium dioxide (TiO2), Iron III oxide (Fe2O3), zinc sulfate (ZnSO4), and copper sulphate (CuSO4). Also, two operating parameters, catalyst load (0.5–2.5 g/L) and mixing speed (30–150 rpm), were investigated at constant UV exposure time (45 min). The treated effluent's pH, color, turbidity, and chemical oxygen demand (COD) were monitored to ascertain photocatalytic efficiency. Catalyst loading (1.5 g/ L), mixing speed (90 rpm), and UV exposure time (45 min), CuSO4 displayed the best results overall for COD removal efficiency of 72.47%, while ZnSO4 was very efficient in removing turbidity and colour with removal efficiencies of 79 and 65.89%, respectively. This study considered CuSO4 as the most cost-effective (R2 = 01) semiconductor photocatalyst to degrade the high organic content of WW.