Mechanism and performance of the hydrolytic chemical recycling of polylactide catalyzed by the protic ionic liquid 2-HEAA

• Published in: Resources, conservation and recycling conservation and recycling, 2024-11, Vol.210, p.107826, Article 107826
• Main Authors: Cháfer, A., Gil-Castell, O., Björling, A., Ballesteros-Garrido, R., Cerisuelo-Ferriols, J.P., Badia, J.D.
• Format: Article
• Language: English
• Subjects: 2-hydroxyethyl ammonium acetate (2-HEAA); Chemical valorization; Hydrolysis; Kinetics; Mechanisms; Polylactide (PLA); Protic ionic liquid (PIL)
• ISSN: 0921-3449; 1879-0658
• DOI: 10.1016/j.resconrec.2024.107826

•Hydrolytic PLA recycling with ionic liquid 2-HEAA: use of catalytic co-solvent for enhancing conversion.•2-HEAA's efficacy: allows mild temperatures, reduces solvent needs, boosts PLA conversion, enables trace-free reuse.•Thermal kinetics: first-order model, low activation energy (112.3 kJ/mol), economical compared to other catalysts.•Optimal conditions: temperature 140 °C, polymer-to-solvent of 1:6, polymer-to-ionic liquid of 1:2.5, conversion >98 %.•2-HEAA's potential: boost PLA chemical recycling, aligned with waste-to-gate approach and circular economy principles. The hydrolytic chemical recycling of polylactide (PLA) aided by the protic ionic liquid 2-hydroxyethyl ammonium acetate (2-HEAA) as a homogeneous catalytic co-solvent was evaluated. In terms of maximization, temperature emerged as the most significant factor, being milder compared to that applied with other catalysts, resulting in potential energy savings. From a cost-efficiency perspective, employing a high solvent proportion was deemed unnecessary, thereby reducing reagent consumption. A higher proportion of ionic liquid leads to higher conversions, which could be trace-free recovered and reused in subsequent recycling steps. The best reaction triplet was a temperature of 140 °C, a mass ratio between PLA and water of 1:6, and a mass ratio between PLA and 2-HEAA of 1:2.5, enhancing the efficiency of PLA conversion under a waste-to-gate circular model in the chemical valorization industry. Thermal kinetics explained by a first-order model, show an apparent activation energy of 112.3 kJ·mol-1, which is lower compared to other ionic liquids. [Display omitted]