Abstract
BackgroundRecycling the ever-increasing plastic waste has become an urgent global concern. One of the most convenient methods for plastic recycling is pyrolysis, owing to its environmentally friendly nature and its intrinsic properties. Understanding the pyrolysis process and the degradation mechanism is crucial for scale-up and reactor design. Therefore, we studied kinetic modelling of the pyrolysis process for one of the most common plastics, polyethylene terephthalate (PET). The focus was to better understand and predict PET pyrolysis when transitioning to a low carbon economy and adhering to environmental and governmental legislation. This work aims at presenting for the first time, the kinetic triplet (activation energy, pre-exponential constant, and reaction rate) for PET pyrolysis using the differential iso-conversional method. This is coupled with the in-situ online tracking of the gaseous emissions using mass spectrometry.ResultsThe differential iso-conversional method showed activation energy (Ea) values of 165–195 kJ mol−1, R2 = 0.99659. While the ASTM-E698 method showed 165.6 kJ mol−1 and integral methods such as Flynn-–Wall and Ozawa (FWO) (166–180 kJ mol−1). The in-situ Mass Spectrometry results showed the gaseous pyrolysis emissions, which are C1 hydrocarbons and H–O-C=O along with C2 hydrocarbons, C5–C6 hydrocarbons, acetaldehyde, the fragment of O–CH=CH2, hydrogen, and water.ConclusionsFrom the obtained results herein, thermal predictions (isothermal, non-isothermal and step-based heating) were determined based on the kinetic parameters. They can be used at numerous scale with a high level of accuracy compared with the literature.
Highlights
Recycling the ever-increasing plastic waste has become an urgent global concern
The kinetic modelling results AKTS thermokinetics package was utilized in this study to facilitate kinetic analysis of polyeth‐ ylene terephthalate (PET) plastic bottle samples using conventional thermo-analytical data, which, in the case of this study, was in the form of TGA
This can allow for the study of the thermal behaviour of the PET samples within the discrete areas of quality assurance and research and development (R&D)
Summary
Recycling the ever-increasing plastic waste has become an urgent global concern. One of the most convenient methods for plastic recycling is pyrolysis, owing to its environmentally friendly nature and its intrinsic properties. This work aims at presenting for the first time, the kinetic triplet (activation energy, pre-exponential constant, and reaction rate) for PET pyrolysis using the differential iso-conversional method. This is coupled with the in-situ online tracking of the gaseous emissions using mass spectrometry. It is possible to add additional value to this waste through processes such as pyrolysis, solvent dissolution, gasification, and other valorisation approaches while promoting the circular economy [10, 11]. This approach of using a waste stream will complete the full cycle of plastic and, directly support and facilitate the concept of the circular economy
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