Hydrolytic chemical recycling of polylactide (PLA) with the protic ionic liquid 2-HEAA: efficiency and energy savings

The research group on Materials and Sustainability (MATS) at the University of Valencia continues to advance in the field of chemical recycling of plastics with its latest publication in the journal Resources, Conservation & Recycling. In the article titled "Mechanism and performance of the hydrolytic chemical recycling of polylactide catalyzed by the protic ionic liquid 2-HEAA", researchers A. Cháfer, O. Gil-Castell, A. Björling, R. Ballesteros-Garrido, J. P. Cerisuelo-Ferriols, and J.D. Badia explore the hydrolytic recycling of polylactide (PLA) using the protic ionic liquid 2-hydroxyethylammonium acetate (2-HEAA) as a homogeneous catalytic co-solvent.

The study reveals that 2-HEAA not only facilitates the conversion of PLA into valuable products but also provides a significant advantage in terms of energy savings, as the reaction temperature is lower compared to other catalysts. According to the analysis, temperature emerges as the most relevant factor for optimizing the recycling process, with 140 ºC being the optimal condition, alongside a PLA-to-water mass ratio of 1:6 and a PLA/2-HEAA mass ratio of 1:2.5.

The study also highlights the economic efficiency of the process, demonstrating that an excess of solvent is not required, thereby reducing reagent consumption. Additionally, 2-HEAA shows excellent reusability, enhancing the sustainability of the process by allowing the ionic liquid to be recovered and reused in successive cycles.

Thermal kinetic results, modeled using a first-order model, reveal an apparent activation energy of 112.3 kJ·mol⁻¹, lower than that of other ionic liquids, suggesting a more efficient and promising process for PLA valorization within a circular waste-to-product model.

Revista: Resources, Conservation & Recycling

Link: https://doi.org/10.1016/j.resconrec.2024.107826

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