Theoretical and experimental study on the reaction mechanism and toxicity evaluation of co-pyrolysis process of hydrogen halide and polyethylene terephthalate

Efficient recycling and disposal of waste plastics is key to protecting the environment. Meanwhile, controlling the emission of hydrogen halide is also a great challenge for the problem of environmental pollution. In this study, the effect of hydrogen halide on the depolymerization mechanism of waste plastics was studied theoretically and experimental (Py-GCMS) using “Treating the wastes with wastes”. The research results show that the presence of hydrogen halide (HF, HCl, and HBr) can promote the depolymerization of polyethylene terephthalate (PET) waste plastics, which makes the reaction easier, and the promoting intensity is HF (about 153.0 kJ/mol) < HCl (about 138.0 kJ/mol) < HBr (about 85.0 kJ/mol). Additionally, through the evaluation of the environmental impact of co-pyrolysis products, it was found that the co-pyrolysis of waste plastics and hydrogen halide reduced the toxicity of the products. These findings are expected to contribute to the understanding of waste conversion mechanisms and risk evaluation in aquatic settings, while also providing theoretical perspectives on reducing pollutant emissions during thermal treatment and sustainable conversion of PET-containing waste alongside hydrogen halide.