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Photocatalytic mineralisation of toxic chlorophenols and removal of Cr (VI) in aqueous solution using cocatalyst decorated TiO2

Shoneye, Ayoola; (2021) Photocatalytic mineralisation of toxic chlorophenols and removal of Cr (VI) in aqueous solution using cocatalyst decorated TiO2. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

One of the limitations confronting conventional water treatment technologies is the complete mineralisation of persistent organic pollutants (POPs) like chlorophenols and their derivatives. Therefore, it is important to find innovative and cost-effective techniques for the safe and complete destruction of these POPs. In the project, the possibility of enhancing the photocatalytic mineralisation activity of very benign titanium dioxide via surface modification by cocatalysts was systematically investigated. A robust impregnation method was used to fabricate Fe(III)/TiO2 composites. Highly dispersed Fe(III) oxide species on TiO2 was optimised to achieve complete mineralisation of a few herbicides (2,4,6-trichlorophenol and 2,4-dichlorophenoxyacetic acid) under uv/visible light irradiation (λ > 320 nm). The consistent results were achieved by HPLC, TOC and UV-vis spectra measurements, which show among three Fe(III) oxide species, Fe4NO3(OH)11, FeOOH and Fe2O3, FeOOH (0.1% Fe) is the best to improve TiO2 activity, representing nearly two times activity of the benchmark PC50 TiO2 photocatalyst for both herbicides tested. Such high activity was attributed to the enhanced photo-generated electron-hole separation and improved generation of hydroxyl radicals. Next, the surface modification of TiO2 with Fe-based alloys was also investigated under similar operating conditions. Both Fe-Cu and Fe-Co oxide alloys were found to improve the photocatalytic performance of optimised Fe/TiO2 towards complete mineralisation of 2,4,6-TCP with 108% and 155% enhancement, respectively in 3 h compared with TiO2. In order to eliminate catalyst recovery cost in slurry/suspension systems, the immobilisation of photocatalysts on a rigid and photo-chemically stable polymer as a robust support was also investigated for the photocatalytic removal of methylene blue and Cr (VI) ions, which is close to the real condition for water treatment. The results were compared with those achieved under slurry/suspension system and indicated the immobilisation is a robust way to implement the technology for real water treatment.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Photocatalytic mineralisation of toxic chlorophenols and removal of Cr (VI) in aqueous solution using cocatalyst decorated TiO2
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10133179
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