PET pyrolysis: Kinetics of a-graphite

Abstract

One of the primary issues nowadays is plastic waste management, where the low recycling rates and accumulation of waste plastic show an exponentially increasing trend with urbanization. Especially, the concern is high with the PET waste generated from food packaging industries. Thus, new technologies are required for waste refining. Pyrolysis is one such technique that will restrict the emission possibilities obvious with the incineration and convert plastic into some value-added end products. However, large scale implementation of pyrolysis technology for plastic waste management requires a thorough understanding of its degradation kinetics along with pyrolysis index (PI) calculation. Here a thorough analysis of the degradation kinetics of PET waste was done with established models to evaluate the activation energy for the reactions. Among all the conventional models discussed, Coats-Redfern shows a 0.95–0.98 R2 value during model fitting. The activation energies were varied from 133.6 to 241.8 kJ/mol. PI value was evaluated at different temperatures to assess lower energy utilization during designing and scaling up the process. The value was found to be maximum at 500°C indicating the scalability of the process at this temperature with lower energy utilization. Qualitative predictions on the production of amorphous graphite oxide (a-graphite) were validated through FTIR, FESEM, Raman, XRD, and UV spectroscopy analyses.