Though synthetic plastics are indispensable in our everyday life, the uncertainty surrounding the sustainability of fossil reserves has led to the development of a novel class of plastics, referred to as bio-based plastics. Poly(lactic) acid (PLA) is the most frequently used member of this family. However, due to the lack of a holistic recycling strategy, its large scale utilization can turn out to be an acute source of plastic pollution in the future. Unlike other attempts directed towards chemical recycling of PLA which violate the basic principles of green chemistry, the following research establishes an eco-friendly recycling concept aimed at the production of a valuable lactate ester through solvent assisted transesterification of PLA waste. The scope of this research is not only limited to the selection of an appropriate system (solvent, nucleophile and catalyst) but also extends to analysing the selectivity of the solvent towards the PLA fraction in a commingled stream and the effect of the concentration of nucleophile and different PLA substrates on the yield of the lactate ester. It was observed that, irrespective of the source of PLA, a high yield of ethyl lactate (approx. 80%) with complete retention of stereochemistry was obtained for a molar ratio of nucleophile per mole repeat unit of PLA (n_nuc:n_rpu) equivalent to 3. Thus, this work represents an attempt towards instituting circular bio-economy by overcoming the engineering and environmental challenges associated with PLA-waste management and production of ethyl lactate; while strictly adhering to the principles of green chemistry and sustainable chemical engineering.

尽管合成塑料在我们的日常生活中是必不可少的，但化石储量可持续性的不确定性导致了新型塑料的开发，这种新型塑料被称为生物基塑料。聚乳酸（PLA）是该家族中最常用的成员。但是，由于缺乏整体回收策略，其大规模利用可能会在将来成为塑料污染的严重来源。与针对PLA进行化学回收的其他尝试违反了绿色化学的基本原理不同，以下研究建立了一种生态友好的回收概念，旨在通过溶剂辅助PLA废物的酯交换反应生产有价值的乳酸酯。本研究的范围不仅限于选择合适的系统（溶剂，亲核试剂和催化剂），还扩展到分析混合流中溶剂对PLA馏分的选择性以及亲核试剂和不同PLA底物浓度对乳酸酯收率的影响。观察到，与亲核试剂的摩尔比/每单位PLA重复数（n）相比，获得了高产率的乳酸乙酯（约80％），且具有完全保留的立体化学，而与PLA的来源无关。_nuc：n _rpu）等于3。因此，这项工作是通过克服与PLA废物管理和乳酸乙酯生产相关的工程和环境挑战，建立循环生物经济的尝试。同时严格遵守绿色化学和可持续化学工程原理。