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Nanostructured materials as potential photocatalysts for water treatment

Alghamdi, Eman 2018. Nanostructured materials as potential photocatalysts for water treatment. PhD Thesis, Cardiff University.
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Abstract

This thesis discusses the latest developments in the use of nanostructured materials in water treatment. The method discussed is heterogeneous photocatalysis which uses titanium dioxide to photo-decompose organic compounds. The thesis seeks to determine the effects of the heterogeneous photocatalysis by experimental means. Methylene blue is used as the organic compound, which should be neutralised, and also acts as an indicator due to its blue colour. The objective of the experiment is to determine the optimum conditions which lead to the release of electron-hole pair. The parameters monitored are the temperature of the solution and the wavelength of the UV light. The optimum thickness of the coating of by spin coating and the modifications of titanium oxide that could increase the efficiency of the process are also determined. Group (VI) or metal transition elements-doped TiO2 nanoparticles (Cr, Mo, W) were synthesised and utilised as catalyst for the decolorisation of aqueous solution contain-ing methylene blue. FT-IR and UV-vis spectroscopy techniques, X ray diffraction (XRD), scanning electron microscopy (SEM) were used to characterise the samples. The results indicated that the doped TiO2 nanoparticles showed higher photocatalytic activity than the pure one.All doped materials display reduced activity compared to their undoped counterparts this suggests the dopant either hinders the electron trans-fer due to recombination or charge trapping resulting the removal of the active species away from the active sites. P25 is usually considered to be the most active catalyst due to the hetro-junction enabling efficient charge separation. The pure anatase phase is better than pure rutile, due to the relativity surface activity and stability of the respective materials. Modification of the chemical structure of TiO2 by Cr, Mo, W doping allows moving the photocatalytic activity of TiO2 towards visible light.The results indicates that films doped with 0.1% exhibit the highest UV and visible light photocatalytic activity.

Item Type: Thesis (PhD)
Date Type: Submission
Status: Unpublished
Schools: Physics and Astronomy
Subjects: Q Science > QC Physics
Uncontrolled Keywords: nanostructured materials, heterogeneous photocatalysis, Methylene blue, electron-hole pair, FT-IR spectroscopy techniques, UV-vis spectroscopy techniques, X ray diffraction (XRD), scanning electron microscopy (SEM)
Date of First Compliant Deposit: 29 May 2019
Last Modified: 29 May 2019 09:28
URI: http://orca-mwe.cf.ac.uk/id/eprint/122923

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