Synergistic formation of chlorinated oxygenated volatile organic compounds and nanoplastic particles during co-thermal degradation of PET and PVC: Implications for recycling emissions and health risks.

内容摘要

Mechanical melting in plastic recycling operates at temperatures dictated by the highest-melting polymer in mixed waste, yet the characteristics of airborne emissions from plastics under these conditions remain poorly understood. This study systematically investigates gaseous products and nanoplastic particles (NPPs) released during individual and co-thermal degradation of polyethylene terephthalate (PET) and polyvinyl chloride (PVC), using integrated online and offline analytical techniques. Results reveal that synergistic interactions accelerated the degradation of both polymers, significantly altering gas- and particle-phase compositions and elevating particle number emissions. Oxygenated volatile organic compounds (OVOCs) accounted for a higher proportion (45.95%) in co-degradation than in individual polymer treatments. NPPs showed enhanced signals for C8H5O3+ and Cl－, indicating the formation of phthalate and chlorinated species, which were confirmed by GC-MS analysis. Notably, chloroesters of terephthalic and benzoic acids increased markedly via the addition of HCl to vinyl ester intermediates. Toxicity prediction modeling suggests these compounds may pose human health risks. These findings provide critical insight into the release of hazardous emissions during thermal processing of mixed plastics and raise concerns about potential hazards associated with plastic waste recycling and human health.