Optimization and High-Efficiency Photocatalytic Degradation of Petroleum Refinery Wastewater using SiO₂/TiO₂ Nanocomposite under UV Irradiation

The critical issue of environmental contamination caused by petroleum refinery wastewater (PRW) has attracted significant attention from researchers due to its harmful effects on human health and ecosystems. The real PRW was successfully treated using Silica-Titania (SiO2/TiO2, with a weight ratio of 2.5/97.5%) as a novel photocatalyst to remove organic compounds from real wastewater in a newly designed photocatalytic radiation chamber. SiO2/TiO2 was prepared by the sol-gel technique and assessed by the XRD, FTIR, FESEM, EDAX, AFM, and BET analysis. Response surface methodology was used to optimize solution pH, catalyst dosage, and reaction time. The results showed that SiO2/TiO2 dosage had the most significant impact on the COD reduction efficiency at optimal conditions of pH 3, SiO2/TiO2 dosage 2.29 g/L, and time 5.46 h, achieving 94% COD removal and a correlation coefficient of 98.54%, with an energy consumption of 1.719 kWh/L. SiO2/TiO2 maintained excellent stability after undergoing five cycles, achieving more than 87.8 % reduction of COD. The outcomes highlighted the synergistic effect between the SiO2/TiO2 photocatalyst and the new chamber design, showing significant enhancements in PRW treatment. Despite these promising results, the study was limited to a single PRW sample and a specific UV intensity. The designed photocatalyst can be examined for various wastewater compositions, scale-up feasibility, and long-term operational stability. Finally, the process revealed efficient performance and showed potential to be a cost-effective and eco-friendly approach for COD reduction from PRW.