Plastic Recovery from Municipal Solid Waste by Solvent Extraction: ACS Sustainable Resource Management

Municipal solid waste (MSW) contains significant amounts of polyethylene (PE) and polypropylene (PP) that are currently underutilized, representing both an environmental challenge and a lost resource. This study investigated the recovery of PE and PP from MSW using solvent extraction methods and the subsequent application of the recovered plastic extracts in fabricating wood−plastic composites (WPC). Plastics were extracted from MSW sourced from Utah (UT) and Michigan (MI) using mixed xylene and toluene as solvents via a modified Soxhlet extraction method. The extraction process was optimized, and the crude plastic extracts were characterized for chloride content, mechanical strength, thermal stability, and rheological properties. WPC were fabricated using pine fiber and crude xylene-extracted plastic and compared to composites made with high-density PE (HDPE). Optimization of the extraction process afforded crude plastic yields of approximately 16 ± 2% for both MI and UT samples with toluene, while higher yields were obtained with xylene (32 ± 3% for MI and 26 ± 3% for UT). Chloride content analysis revealed PVC contamination of 0.49−1.2%. Solvent recovery exceeded 90−96%, indicating potential for scalable implementation. The crude-extracted plastics contained plasticizers and fatty acids, which had a detrimental effect on tensile properties. Acetone washing to remove plasticizers improved the plastic tensile strength to 10.8 MPa, comparable to virgin LDPE. WPC produced using crude-extracted plastic exhibited lower mechanical properties than those produced with HDPE.