Thesis

Visible light harvesting nanocomposite heterojunction photocatalysts for remediating crude oil contaminated water

Creator
Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2024
Thesis identifier
  • T16988
Person Identifier (Local)
  • 202065542
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • The growth of the world's population and the resultant increase in energy demand and industrialisation have led to an increase in the release of hydrocarbons into the environment as a result of crude oil spills. Given its significant potential for the degradation of organic pollutants, solar photocatalytic oxidation has gained a prominent position as an advanced oxidation technique in environmental remediation due to its outstanding characteristics such as environmental friendliness, low cost, and sustainability. Since visible light accounts for about 43% of the solar spectrum compared to UV light, visible light semiconductor photocatalysts have attracted great attention from the scientific community. This study investigates the visible light photocatalytic degradation of crude oil in water using novel photocatalysts synthesised by a Sequential Ionic Layer adsorption and Reaction (SILAR) method, by incorporating bismuth oxyhalides (BiOX, X = I, Cl) and silver-based compounds (Ag2O and AgI) to form heterojunctions with TiO2. The novelty of this research lies in the tailored synthesis of BiOI-Cl/TiO2 and Ag2O/AgI/TiO2 nanocomposites aimed at enhancing visible light absorption and photocatalytic degradation of crude oil hydrocarbons in water. The photocatalytic degradation activities of the photocatalysts were 70.56%, 85.62%, 89.11% and 91% of 200 ppm crude oil for pure TiO2, BiOI/TiO2, BiOI-Cl/TiO2 and Ag2O/AgI/TiO2, respectively. The bandgaps of 3.21 eV, 2.02 eV, 2.35 eV and 2.32 eV were observed for TiO2, BiOI/TiO2, BiOI-Cl/TiO2 and Ag2O/AgI/TiO2 respectively. The results demonstrate the enhanced visible light absorption of the synthesised nanocomposite photocatalysts, resulting in improved degradation efficiency of crude oil in water compared to pure TiO2. The efficiency of TiO2 in degrading crude oil was mainly due to adsorption resulting from its large surface area compared to the modified nanocomposites with partly photolysis. The remarkable activities of the heterojunction composites could be attributed to the improved optical property, enhanced charge separation and transfer, and synergistic effects of the internal electric field resulting from the heterostructures between TiO2 and the sensitiser composites. Plausible degradation mechanisms were proposed based on the bandgap energies and the results of scavenging experiments. The study concludes that the synthesised photocatalysts show promising potential for practical applications in the treatment of crude oil contaminated water, providing a viable solution for environmental remediation. Overall, the study highlights the potential of tailored visible light nanocomposite photocatalysts for the efficient and sustainable degradation of petroleum hydrocarbons in aquatic environments.
Advisor / supervisor
  • Ivaturi, Aruna
Resource Type
Note
  • Previously held under moratorium from 12/06/2024 until 12/06/2025.
DOI
Funder
Embargo Note
  • Access is restricted to Strathclyde users until 12/06/2029.

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