Titanium silicalite-1 macrostructures for use in photocatalytic removal of organic pollutants from aqueous media

Ormond, Sean Patrick Dennis (2015) Titanium silicalite-1 macrostructures for use in photocatalytic removal of organic pollutants from aqueous media. Masters by Research thesis (MSc), Manchester Metropolitan University.

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Abstract

Commercial photocatalyst are in the form of nanopowders, causing aggregation, separation issues and loss of material upon regeneration. This work aims at developing free-flowing photocatalysts in the form of macroscopic beads, which are easily recoverable from solutions. In this study, hierarchically porous TS-1 macroscopic beads were prepared via the resin templating method. Characterisation of the beads was carried out using the following methods: XRD, Raman, nitrogen adsorption/desorption, SEM and EDX. Ti content of the beads was varied in the range of 1 to 7 wt.%, with corresponding surface areas of the beads produced ranging from 725 to 350 m2 g-1. The beads were comprised of a large amount of amorphous material, which was required in order to achieve a high level of mechanical stability in the beads. Evaluation of the photocatalytic activity of the TS-1 beads was carried out via first order degradation kinetics of MB dye under UV irradiation. MB concentrations during the photocatalytic process were determined by UV-vis spectroscopy. CristalACTiV™ PC500, a commercially available nano-anatase photocatalyst, was used as a reference material. The TS-1 beads displayed similar rates of MB degradation independent of the Ti content, but the rates of degradation were 1.2 to 1.5 times lower than CristalACTiV™ PC500. The macroscopic shape of the TS-1 beads allows for easy separation by decanting from exhausted MB solutions after UV irradiation and reuse in subsequent cycles of photocatalytic testing. Regeneration of the catalyst was not required and no appreciable loss of photocatalytic activity was observed in up to five cycles.