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Photocatalytic Hydrolysis─A Sustainable Option for the Chemical Upcycling of Polylactic Acid

Garratt, Antonia; Nguyen, Klaudia; Brooke, Alexander; Taylor, Martin J.; Francesconi, Maria Grazia


Antonia Garratt

Klaudia Nguyen

Alexander Brooke


Plastic waste is a critical global issue, yet current strategies to avoid committing plastic waste to landfills include incineration, gasification, or pyrolysis high carbon emitting and energy consuming approaches. However, plastic waste can become a resource instead of a problem if high value products, such as fine chemicals and liquid fuel molecules, can be liberated from controlled its decomposition. This letter presents proof of concept on a low-cost, low energy approach to controlled decomposition of plastic, photocatalytic hydrolysis. This approach integrates photolysis and hydrolysis, both slow natural decomposition processes, with a photocatalytic process. The photocatalyst, α-Fe2O3, is embedded into a polylactic acid (PLA) plastic matrix. The photocatalyst/plastic composite is then immersed in water and subjected to low-energy (25 W) UV light for 90 h. The monomer lactide is produced as the major product. α-Fe2O3 (6.9 wt %) was found to accelerate the PLA degradation pathway, achieving 32% solid transformation into liquid phase products, in comparison to PLA on its own, which was found to not decompose, using the same conditions. This highlights a low energy route toward plastic waste upgrade and valorization that is less carbon intensive than pyrolysis and faster than natural degradation. By directly comparing a 25 W (0.025 kWh) UV bulb with a 13 kWh furnace, the photocatalytic reaction would directly consume 520× less energy than a conventional thermochemical pathway. Furthermore, this technology can be extended and applied to other plastics, and other photocatalysts can be used.


Garratt, A., Nguyen, K., Brooke, A., Taylor, M. J., & Francesconi, M. G. (2023). Photocatalytic Hydrolysis─A Sustainable Option for the Chemical Upcycling of Polylactic Acid. ACS Environmental Au, 3(6), 342–347.

Journal Article Type Article
Acceptance Date Sep 26, 2023
Online Publication Date Oct 2, 2023
Publication Date Nov 15, 2023
Deposit Date Oct 3, 2023
Publicly Available Date Oct 3, 2023
Journal ACS Environmental Au
Print ISSN 2694-2518
Electronic ISSN 2694-2518
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 3
Issue 6
Pages 342–347
Keywords Polylactic acid; Plastic upcycling; Photocatalysis; Sustainability; Low energy; Processes; Depolymerization
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