Treatment of real petroleum refinery wastewater using SiO₂/TiO₂ nanocomposite induced by UV–visible light

Authors

  • Sarmad A. Rashid Department of Chemical Engineering, College of Engineering, University of Baghdad, Baghdad 10001, Iraq https://orcid.org/0000-0003-1756-1317
  • Wadood T. Mohammed Department of Chemical Engineering, College of Engineering, University of Baghdad, Baghdad 10001, Iraq https://orcid.org/0000-0002-2769-8053
  • Harouadi Zine Eddine Hydrocarbon and Petrochemical Process Department/ Faculty of Engineering/ University of Pannonia / Veszprém, 8200, Hungry

DOI:

https://doi.org/10.31699/IJCPE.2026.2.1

Keywords:

COD reduction; SiO2/TiO2 nanocomposite; photocatalytic degradation; PRW; scavenger

Abstract

   Petroleum refinery wastewater (PRW) is becoming a big problem for both people and the environment, so researchers have been trying harder to find better ways to treat it. One option that looks really promising is using advanced oxidation processes (AOPs) to break down all the pollutants inside this wastewater. In this study, new-designed photoreactor was used to conduct a photocatalysis approach that aimed to remove the chemical oxygen demand (COD) from PRW collected from Al-Diwaniya refinery in the south of Iraq. The geometrically optimized photoreactor enhances the formation of the free radicals required for efficient degradation by maximizing mass transfer and light dispersion. Bare TiO₂ and SiO₂/TiO₂ were fabricated as photocatalysts with the sol-gel technique and then examined by the XRD, FTIR, FESEM, AFM, BET, UV-DRS, and PL analysis. Results showed that, the optimal SiO₂/TiO₂ ratio was 5/95% (S-5) achieving 90% COD reduction efficiency with a photocatalyst dosage of 2 g/L, a reaction time of about 4 h, and using 8 UV-C lamps (8 W each). Under these conditions the process consumed 0.512 kWh/L electricity energy (EE/O). The results demonstrated that COD reduction exhibits behavior consistent with pseudo first order kinetics. In addition, the scavenger experiments revealed that the COD was primarily degraded by the ⦁O₂- radical. After five cycles, the photocatalyst S-5 maintained its stability and continued to remove over 82% of the COD. Refinery effluent was significantly better treated after using this innovative reactor design in conjunction with the SiO₂/TiO₂ photocatalyst. It provides an ecological, more efficient, and less expensive way to lower COD in PRW.

Received on 15/12/2025

Received in Revised Form on 27/02/2026

Accepted on 28/02/2026

Published on 30/06/2026

Author Biographies

  • Sarmad A. Rashid, Department of Chemical Engineering, College of Engineering, University of Baghdad, Baghdad 10001, Iraq

    I am an Assistant Professor in the Department of Chemical Engineering, College of Engineering, University of Baghdad. My academic activities include teaching several undergraduate courses within the department, supervising undergraduate student projects, and conducting scientific research. I have authored and co-authored numerous research papers published in both local and international peer-reviewed journals. My research interests focus on mass transfer processes, water treatment, and advanced oxidation processes.

  • Wadood T. Mohammed, Department of Chemical Engineering, College of Engineering, University of Baghdad, Baghdad 10001, Iraq

    I am a Professor in the Department of Chemical Engineering, College of Engineering, University of Baghdad. I have taught numerous undergraduate and graduate courses and have supervised many students at both levels. Additionally, I have published numerous research papers in local and international journals. My research interests include mass transfer processes, water treatment, and advanced oxidation processes.

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2026-06-30

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Vol. 27 No. 2 (2026): Iraqi Journal of Chemical and Petroleum Engineering

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Rashid, S. A., Mohammed, W. T., & Zine Eddine, H. (2026). Treatment of real petroleum refinery wastewater using SiO₂/TiO₂ nanocomposite induced by UV–visible light. Iraqi Journal of Chemical and Petroleum Engineering, 27(2), 1-17. https://doi.org/10.31699/IJCPE.2026.2.1

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