Visible light mediated refinery waste degradation using noble metal nanoparticle composites Geniece Hallett-Tapley 1 , Megan Ethier 2 Department of Chemistry, Saint Francis Xavier University, Antigonish, Nova Scotia, Canada Polyaromatic hydrocarbons (PAH), are commonly found in refinery waste products and pose a threat to human health and the environment. PAH compounds are of significant environmental concern due to their high toxicity, mutagenicity, and carcinogenicity. Current methods in PAH remediation include filtration, adsorption, and bacterial-mediated oxidation. However, these methods face significant drawbacks in harsh environments. A potential solution to this issue is semiconductor photocatalysis and advanced oxidative processes (AOP) using visible light. This project uses Au-doped metal oxide composites to photodegrade common PAH compounds. Noble metal nanoparticles are used to extend the light activation into more favourable visible wavelength regions, and away from the less desirable UV activation of metal oxide semiconductors. Implementation of heterogenous catalysis is favourable for material recyclability, and no harsh chemicals are needed to initiate the reaction. Hydrogen peroxide is added to the reaction as Fenton reagent, further oxidizing the PAH molecules. Preliminary results have demonstrated complete PAH degradation of 5 μM pyrene, phenanthrene, benzanthracene, fluorene, and anthracene samples in under 60 minutes of green LED exposure. The effects of pollutant concentration, irradiation time, H 2 O 2 concentration, environmental pH, salinity, differing semiconductor supports have been investigated using GCMS and HPLC analysis. The catalyst underwent 6 recyclability trials exhibiting great success and minimal loss of catalyst. The mechanism of PAH photooxidation is currently under investigation. However, preliminary results have shown CO 2 gas evolution and a strong dependence on the use of a Fenton reagent for hydrogen atom abstraction.
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