Chemical Recycling and Upcycling of Polylactic Acid Mixed Plastic Waste

Poly(lactic acid) (PLA) is a promising biodegradable alternative to traditional petrochemical-based resources, widely utilized in the 3D printing and packaging industries. PLA is a polyester made from the polymerization of lactic acid (LA) monomers, which are obtained through fermentation of renewable biomass resources. Despite the eco-friendly advantages of PLA, the extensive use of it requires end-of-life treatment and efficient disposal methods to mitigate environmental impact. The project proposes an innovative approach to the chemical recycling of PLA waste products via alkaline hydrolysis under conventional heating, a process that breaks down the polymer into its monomer, lactic acid, specifically in a form of calcium lactate, a value-added monomer because of its versatile and beneficial applications. To determine optimized hydrolysis conditions, design of experiments, specifically, Box-Behnken Design (BBD) was employed to maximize both the conversion of PLA and the yield of the calcium lactate monomer, all while adhering to the green chemistry principles. Within 30 minutes, the proposed hydrolytic depolymerization technique was able to facilitate 81-100% conversion of various PLA products into calcium lactate monomers, demonstrating both high efficiency and environmentally friendly conditions. The obtained calcium lactate was further processed to produce popping boba as a model potential application. The developed method offers an economically attractive and ecologically sustainable solution for post-consumer PLA recycling and upcycling of the produced monomer, calcium lactate. By enhancing the recycling process, this project contributes significantly to reducing plastic waste and promoting a circular economy in the bioplastics sector, ultimately benefiting both the environment and industry.