This study investigated the photocatalytic degradation of hydrocarbon pollutants in petroleum refinery wastewater (PRWW) using graphene oxide (GO)-based metal oxide composites as photocatalysts. GO was synthesized from waste plant biomass using modified Hummer’s method. Composites of various metal oxides and GO were prepared by loading different weight percentages of TiO 2 , Fe 2 O 3 , and ZnO through the wet impregnation method. The composition and morphology of the photocatalysts were evaluated by FTIR, XRD, SEM, TGA, and EDX analysis. Batch mode catalytic oxidation experiments were conducted on PRWW with an initial chemical oxygen demand (COD) of 986 mg/L, at pH 8.5, temperature 25–30 °C, reaction time 50 min, and catalyst dose of 0.02 g per 20 mL of sample. It was observed that maximum COD removals of 96% and 100% were achieved by photocatalysts ZG11 (ZnO/GO 1:1) and TZG111 (TiO 2 /ZnO/GO 1:1:1), respectively. GC–MS analysis showed that hydrocarbon compounds were absent in the treated PRWW sample; only traces of oxygenated hydrocarbons were found. This method can be applied to large-scale industrial wastewater treatment. This study offers an effective approach to improve the removal rate of high COD from PRWW and makes a practical contribution to wastewater treatment technology.
Ahmad et al. (Tue,) studied this question.