Advanced Analytical Framework for Pyrolysis Product Characterization and Emission Profiling in Mixed Plastic Waste: Implications for Recycling Strategy

Chemical recycling of mixed plastic waste can return polymers to fuel- and feedstock-range hydrocarbons, but legacy additives and non-intentionally added substances (NIAS) may persist in the products or leach during use. We investigated six polyolefin-rich wastes (P1–P6) by analytical pyrolysis coupled to comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (Py-GC×GC-TOF-MS) and profiled potential emissions from three consumer-grade plastics (P7–P9) via headspace/solvent-extraction GC–MS and water-migration tests. When the plastics were polysized at 650°C, the resulting pyrolysates are dominated by aliphatic hydrocarbons (C₅–C₃₀): n-paraffins and α-olefins for PE-rich feeds, and branched olefins with modest mono-aromatics for PP. Oxygenates are negligible in non-oxidized feeds but persist at low levels in weather-aged HDPE, consistent with carry-through of pre-existing carbonyls; one aged film (P5) shows an epoxide spike (~5–6 area %). Across oils we identify hallmark NIAS from antioxidant packages (e.g., 2,4-di-tert-butylphenol; Irganox®-1010 spiro-dione) at trace to sub-percent levels, while heavy polycyclic aromatics are not detected above method limits. A 3D GC×GC visualization highlights the dense, resolved hydrocarbon envelope and the minor heteroatom features that guide upgrading targets. VOC/SVOC and leachate analyses (P7–P9) reveal mainly low-intensity hydrocarbons, esters, and fragrance/cosmetic residues; no phthalates were detected in the tested samples, although caprolactam and other additive-related NIAS occur sporadically. Collectively, the results indicate that well-sorted polyolefins yield oils suitable for refining to fuels or monomers, but quality assurance should address oxygenate tails in oxidized PE and antioxidant-derived NIAS.