Comparative study on development of novel catalytic oxidation for removing emerging contaminants
Abdul Hannan Asif
Date of Award
Doctor of Philosophy
School of Science
‘Wastewater treatment’ is not itself a new concept, where global water bodies have been polluted since the evolution of mankind. As a result of human activities including domestic, industrial and commercial practices, levels of water pollution through aqueous contaminants are increasing every day. Moreover, rapid industrialisation and recent human progress has given rise to a new classification of pollution, that of emerging contaminants (ECs). Further, these chemicals are highly resistant to biodegradation and are capable of travelling, where they can penetrate from one part of the world to another. Whilst traditional wastewater treatment techniques, such as adsorption, might be effective in combating these chemicals, their production of sludge is a major drawback that leads to secondary contaminants.
Advance oxidation processes (AOPs) have gained much attention within environmental remediation, owing to their ability to completely mineralise organic pollutants into less-toxic mineral caids, CO2 and water. The process efficiency of this mineralisation is further improved when it is coupled with nanotechnology. Accordingly, nanostructured transition metal oxides demonstrate exceptional catalytic activity in AOPs. Hematite (α˗Fe2O3), the most stable form of iron oxide, has been demonstrated as an excellent example of this, where its distinct properties, such as high specific surface area, interfacial charge-transfer properties and lower band gap, have made it a promising candidate for AOPs. Moreover, hematite’s good catalytic stability, non-toxic nature, low cost and chemical inertness have rendered it effective in versatile applications.
This thesis presents novel strategies for the preparation and modification of α-Fe2O3 nanostructures. Several techniques, such as metal doping, formation of bimetallic oxides, morphological and facet engineering and integration with carbonaceous structures have been applied to enhance the catalytic and photocatalytic activity of α-Fe2O3. Further, facile hydrothermal, solvothermal and thermal treatment methods have been adopted for the design and formation of desired nanostructures. The physical properties and surface chemistry of these as-prepared nanostructures have been unveiled via several advanced characterisation techniques, for example, XRD, XPS, FT-IR, UV-vis, and PL, amongst others. Following this, these materials were applied in AOPs, where they were shown to successfully activate peroxygens (peroxymonsulfate (PMS) and hydrogen peroxide (H2O2)) for the removal of ECs, such as those in pharmaceutical and personal care products (PPCPs). In this study, level of modification was set as a key performance indicator, whereby optimum modification conditions were determined for preserving the best catalytic characteristics. The influence of reaction parameters including pH, catalyst loading, oxidant loading and reaction temperature were comprehensively investigated to optimise reaction kinetics. Electron paramagnetic resonance (EPR) was used to identify the generation of radical and free radical species, whereby their specific role in degradation kinetics was confirmed by performing quenching experiments. At the end, the mineralisation ability of as-prepared catalytic materials was evaluated by performing total organic carbon analysis, where ultra-high performance liquids spectroscopy (UHPLC) chromatograms were used to propose degradation pathways. In summary, the current work serves as a bridging tool between nano structural engineering and reaction engineering for environmental remediation. The former provides fundamental groundwork for the development of efficient catalysts, where the latter expands pathways for real-world applications.
Access to this thesis is embargoed until 8th March 2026.
Asif, A. H. (2023). Comparative study on development of novel catalytic oxidation for removing emerging contaminants. https://ro.ecu.edu.au/theses/2634