Application of photocatalytic processes for oilfield produced water treatment

  • Kingsley Amakiri

Student thesis: Doctoral Thesis


Every aspect of oil operation has had significant negative impacts on the environment, albeit to varying degrees, and that the ecosystems, particularly those proximate to the petroleum industries, have been subject to environmental degradation resulting from operational activities thus the environmental consequences have had diverse economic impact on the local population, particularly in areas were produced water is discharged into marine environment, and onshore regions proximate to farmlands, rivers and streams. Conventional treatment technologies for contaminants in produced water are well-established and have been able to remove a considerable amount of suspended solids, oil, grease, and heavy metals, depending on the technology. However, despite being proven effective, these systems are still not able to remove dissolved organic compounds from produced water and sometimes display low efficiency for removing organic compounds and pollutants that are present in small concentration. The need for technological innovation to efficiently remove contaminants of emerging concern (such as endocrine disruptors) during produced water treatment has stimulated research on advanced oxidation processes (AOPs) using photocatalysis.

Photocatalysis has demonstrated to have high potential for removing persistent organic pollutants. In this thesis, several photocatalysts that are considered suitable for environmental applications, such TiO2, ZnO and CeO2, were synthesised to study the photocatalytic degradation of phenol, benzene and naphthalene. The physicochemical properties of the catalysts were characterised. The physicochemical properties of the catalysts were characterised with a range of relevant analytical techniques such as scanning electron microscopy (SEM), X-ray Diffraction (XRD), UV-VIS Diffuse Reflectance Spectroscopy (DRS), Brunauer-Emmett-Teller (BET) technique, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS)Thermogravimetric analysis (TGA) and high-performance liquid chromatography (HPLC) techniques.TiO2 proved to be more efficient compared to both the other synthesised and commercial photocatalysts. One significant challenge for the degradation of organic compounds in water is to generate enough hydroxyl radicals to achieve the total degradation of organic compounds. Nitrogen doped-TiO2 and phosphate modified TiO2 photocatalysts were successfully synthesized through the microwave assisted sol gel method. While the simultaneous degradation of phenol, benzene and naphthalene achieved 82,89.2,76.9%. Phosphate modified TiO2 gave a better performance with 94, 97.7 and 93.9% degradation for phenol, benzene and naphthalene. Largely, the outcomes of this thesis study will aid in the development of a more sophisticated alternative for the treatment of PW.
Date of Award27 Sep 2022
Original languageEnglish
SupervisorAthanasios Angelis-Dimakis (Main Supervisor) & Jeremy Hopwood (Co-Supervisor)

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