In-depth Study of Trichloroethylene Photodegradation by Titanium Dioxide Nanoparticles: Anatase versus Brookite

Victoria Magyar

vmagyar@unca.edu

CHEMISTRY & BIOCHEMISTRY

Trichloroethylene, TCE, is a volatile industrial solvent that has been identified as a human carcinogen and contaminant by the US EPA. Titanium dioxide, TiO2, is a widely available environmental photocatalyst that is able to degrade volatile organic contaminants under UV light. TiO2 is capable of crystallizing in three polymorphic structures: anatase, rutile, and brookite. Brookite TiO2 is highly under researched and shows potential as an effective photocatalyst. In this study, a detailed comparison of purchased and synthesized Brookite, Brookite-Rich, Anatase, and Anatase-Rich NPs was conducted to determine effectiveness in the photodegradation of TCE. Photocatalysis of aqueous solutions containing TCE and TiO2 NPs were exposed to UV-light and analyzed with GC-MS at desired minute intervals in accordance with EPA methods. Samples were run in neutral, acidic, and alkaline conditions. In all alkaline conditions no changes to the degradation rate of TCE were experienced. In neutral conditions purchased Anatase and Brookite had comparable activity both degrading TCE effectively. Purchased and synthesized Anatase-Rich NPs performed worse than purchased Anatase. Purchased anatase and synthesized anatase performed similarly in TCE degradation, both degrading 80% of TCE in 3 mins of UV. Brookite-rich degraded 90% of TCE in 2 mins of UV exposure increasing the photocatalytic efficiencies of purchased NPs. Purchased Brookite-Rich outperformed all five: purchased Brookite, synthesized Brookite-Rich, Anatase, purchased and synthesized Anatase-Rich. Purchased brookite degraded 85% of TCE in 3 mins of UV whereas, synthesized brookite degraded 99% of TCE in 1 min of UV. Synthesized Brookite had a significant increase in rate of degradation, outperforming every other sample. Basic conditions did not increase degradation rate of TCE and extreme acidic pH increased TCE degradation with and without purchased brookite NPs. The results of this project provide evidence towards the optimal conditions for the photodegradation of TCE with TiO2 NPs.

Dec-14-2023