Luo Hui, Yang Dingchang, Sadhukhan Jhuma, Costica Verdeluz, Dorey Robert, Song Qilei, Titirici Maria-Magdalena
School of Engineering, University of Surrey, Stag Hill Campus, Guildford, GU2 7XH, UK.
Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
ChemSusChem. 2025 Jul 17;18(14):e202500503. doi: 10.1002/cssc.202500503. Epub 2025 May 20.
Poly(lactic acid) (PLA), a biodegradable plastic derived from starch, has gained prominence as a sustainable alternative to petroleum-based plastics. However, the slow degradation of PLA in natural environments and contamination of recycling streams due to incompatibility with other plastics highlight the need for efficient recycling techniques. This study reports a sustainable closed-loop PLA recycling strategy by hydrolysis depolymerization under moist-solid condition and recovery of the valuable monomer lactic acid. By employing ball milling and resonance acoustic mixing, the effects of milling speed, time, ball size, alkali type, and ageing on lactate yield are investigated, to optimize the performance and the efficiency of mechanical and moist-solid conditions in polymer chain scission without bulk heating is demonstrated. Furthermore, a bipolar membrane electrodialysis process for conversion of lactate to lactic acid is integrated with simultaneous NaOH production, enhancing the sustainability of the recycling process. Life-cycle assessment (LCA) is employed to assess the environmental impact of such PLA recycling approach for lactic acid production and provide recommendations for future improvements. This work demonstrates the effectiveness and environmental benefits of mechanically induced moist-solid chemical recycling and integration with advanced membrane separation processes, offering a promising pathway for sustainable PLA waste management and lactic acid production.
聚乳酸（PLA）是一种由淀粉衍生而来的可生物降解塑料，作为石油基塑料的可持续替代品已受到广泛关注。然而，PLA在自然环境中降解缓慢，且由于与其他塑料不相容而导致回收流受到污染，这凸显了高效回收技术的必要性。本研究报告了一种可持续的闭环PLA回收策略，即在湿固相条件下通过水解解聚回收有价值的单体乳酸。通过采用球磨和共振声混合技术，研究了研磨速度、时间、球尺寸、碱类型和老化对乳酸产量的影响，以优化性能，并证明了在不进行整体加热的情况下，机械和湿固相条件在聚合物断链方面的效率。此外，将乳酸转化为乳酸的双极膜电渗析过程与同时生产NaOH相结合，提高了回收过程的可持续性。采用生命周期评估（LCA）来评估这种PLA回收方法对乳酸生产的环境影响，并为未来的改进提供建议。这项工作证明了机械诱导湿固相化学回收以及与先进膜分离过程相结合的有效性和环境效益，为可持续的PLA废物管理和乳酸生产提供了一条有前景的途径。
