Bio-synthesized ZnO nanoparticles and sunlight-driven photocatalysis for environmentally-friendly and sustainable route of synthetic petroleum refinery wastewater treatment

Abstract

The design of a green photocatalytic system that harnesses renewable and eco-friendly constituents holds the potential to offer valuable insights into alternative strategies for treating toxic multi-components in refinery water effluents. A significant challenge in implementing a practical and viable approach is the utilization of solar energy—an abundant, natural, and cost-effective resource—for photochemical processes within advanced oxidation processes. In this study, we explored the use of zinc oxide nanoparticles (ZnO NPs) as photocatalyst prepared via an environmentally friendly synthesis approach, resulting in the formation of crystalline wurtzite nanoparticles, with an average size of about 14 nm relatively spherical in shape. Notably, the extract derived from Moringa oleifera was employed in this investigation. These nanoparticles were characterized and validated using various characterization techniques, including X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. For comparison, conventionally synthesized ZnO NPs were also included in the evaluations. The findings reveal that, under illumination, biosynthesized ZnO nanoparticles (NPs) exhibit photocatalytic performance in effectively breaking down the organic compounds present in synthetic petroleum wastewater. Photochemical analysis further illustrates the degradation efficiency of Green-ZnO, which, within 180 min of irradiation resulted in 51%, 52%, 88%, and 93% of removal for Phenol, O-Cresol. Under optimal loading conditions, NPs produced via the green synthesis approach perform better when compared to chemically synthesized ZnO. This significant improvement in photocatalytic activity underscores the potential of eco-friendly synthesis methods in achieving enhanced water treatment efficiency.

Advancing Wastewater Treatment: A Comparative Study of Photocatalysis, Sonophotolysis, and Sonophotocatalysis for Organics Removal

“…Solar-assisted heterogeneous photocatalysis was put to use in the study by El Golli [97], with the intention of removing four aromatic (toluene, phenol, o-cresol, and xylene) hydrocarbons, frequently found in refinery effluent. ZnO nanoparticles synthesized via a conventional chemical route (chem-ZnO) and green ZnO nanoparticles (green-ZnO), prepared via a green synthesis route using Moringa oleifera leaves extract, were applied as photocatalysts.…”