Chemical Upcycling of PS via Visible Light Induced Photocatalysis William Cheung, Justin Zheng, Yalan Xing* Department of Chemistry, Hofstra University, Hempstead, NY
Introduction
IR Spectra
Mechanism of PSOOH Formation
The buildup of addition polymers is a major contributor to climate change due to their long natural lifespans. Photochemistry, a subset of green chemistry, aims to design polymers for degradation in order to minimize waste and convert them into more valuable compounds after their end of function.
The reaction proceeds as a chain oxidation that is initiated by a photocatalyst. https://www.nytimes.com/2019/10/11/science/plastics-ocean-degrade.html
Acidic Degradation of PSOOH Current Methods & Limitations of Polymer Degradation
Future Plans ●
Expensive, energy intensive, and time-consuming ● Incomplete oxidation of the polymer chain ● Involves use of toxic or harmful reagents ● Products generated are not particularly valuable ●
Under acidic conditions, PSOOH can be further degraded to produce molecules of phenol and a biodegradablepoly-1,3-diketone that can be converted into acetic acid.
Experiment with different photocatalysts or wavelengths of light to maximize percent yield ● Confirm formation of polystyrene hydrogen peroxide using IR spectroscopy and NMR ● Treat polystyrene hydrogen peroxide under acidic conditions to form a poly-1,3-diketone ● Deploy experimental design commercially if reaction is successful
Conditions for PSOOH Formation
References & Acknowledgements ❖
Our Proposal
Huang, Z.; Shanmugam, M.; Liu, Z.; Brookfield, A.; Bennett, E. L.; Guan, R.; Vega Herrera, D. E.; Lopez-Sanchez, J. A.; Slater, A. G.; McInnes, E. J. L.; Qi, X.; Xiao, J. Chemical Recycling of Polystyrene to Valuable Chemicals via Selective Acid-Catalyzed Aerobic Oxidation under Visible Light. Journal of the American Chemical Society 2022, 144 (14), 6532– 6542. https://doi.org/10.1021/jacs.2c01410.
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Inoa, J.; Patel, M.; Dominici, G.; Reem Eldabagh; Patel, A.; Lee, J. D.; Xing, Y. Benzylic Hydroperoxidation via VisibleLight-Induced Csp3–H Activation. Journal of Organic Chemistry 2020, 85 (9), 6181–6187. https://doi.org/10.1021/acs.joc.0c00385.
Entry Catalyst
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Few research articles have characterized the formation of a polystyrene hydrogen peroxide intermediate during the degradation of polystyrene. We propose that this intermediate can undergo further series of degradations to ultimately generate valuable products including acetic acid and phenol.
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Resultsb
Oxygen Source
Light
Benzene/CH3CN (1:1)
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Oxidation
Benzene/CH3CN (1:1)
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Benzene/CH3CN (1:1)
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No catalyst Benzene/CH3CN (1:1)
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Li, T.; Vijeta, A.; Casadevall, C.; Gentleman, A. S.; Euser, T.; Reisner, E. Bridging Plastic Recycling and Organic Catalysis:
Photocatalytic Deconstruction of Polystyrene via a C–H Oxidation Pathway. ACS Catalysis 2022, 12 (14), 8155–8163. https://doi.org/10.1021/acscatal.2c02292. ❖
Nabi, I.; Bacha, A.-U.-R.; Ahmad, F.; Zhang, L. Application of Titanium Dioxide for the Photocatalytic Degradation of Macro- and Micro-Plastics: A Review. Journal of Environmental Chemical Engineering 2021, 9 (5), 105964. https://doi.org/10.1016/j.jece.2021.105964.
A Special Thanks To:
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Dr. Yalan Xing Fellow Xing Research Lab Members Abigail Hart and Justin Alvarez Department of Chemistry at Hofstra University