Polyethylene Recovery from Multilayer Plastic Packaging Waste

Multilayer plastic packaging waste (MPPW) represents a major challenge for waste management due to its widespread use in single-use applications and its complex, heterogeneous structure. Variations in polymer composition, layer thickness and number of layers significantly hinder conventional recycling processes, leading most MPPW to be disposed of through landfilling or incineration. This study presents the development and optimization of a dissolution-precipitation process using toluene to recover polyethylene (PE) from MPPW. The proposed method successfully produced PE with less than 5 wt% polypropylene (PP), meeting common recycling quality requirements. Design of experiments (DoEs) combined with response surface methodology (RSM) was applied to evaluate the influence of key operating parameters, including temperature, dissolution time, solvent to waste ratio and agitation speed, to identify optimal processing conditions. The results demonstrated that temperature had the most significant influence on both dissolution yield and polymer purity. Optimal conditions of 100 °C, 30 min, 400 rpm, and a solvent-to-waste ratio of 15 mL/g resulted in a total recovery yield of 39.1% with a polymer composition of 97.7 wt% PE and 2.3 wt% PP. Owing to the use of established and scalable unit operations, the process shows strong potential for industrial-scale implementation without requiring complex or specialized infrastructure.