Understanding the kinetics of waste plastic catalytic pyrolysis under microwave irradiation for enhanced resource valorization

The increasing accumulation of ABS plastic waste poses significant environmental challenges, necessitating efficient methods for its disposal and recycling. The pyrolysis of the ABS plastic waste was performed under various heating programs including constant heating rate (27.5, 42.2 and 65 K min⁻¹), and sample-controlled reaction rate (0.01 min⁻¹) to obtain the TG curves using the in-house developed microwave assisted thermogravimetric analyzer. Fe-impregnated SiC was used as thermal and chemical catalyst, while neat SiC played only thermal catalyst role. The modified Sestak-Bergren equation used to model the TG data by Pearson's linear correlation and associated parameters n = 1.129 and m = 0.27 was achieved. The comparison of normalized form of the conversion function (f (α)/f (0.5)) with the most common models of solid-state reactions showed that random scission model (L2) was the most suitable approach to physically explain the pyrolysis of ABS plastic waste. Furthermore, by applying isoconversional kinetic analysis, the variation of activation energy (Eα) with conversion value was approximately constant. The Eα obtained was 140.5 and 63.7 kJ/mol with SiC and Fe/SiC, respectively. These findings hold practical implications for industrial applications or waste management strategies, particularly when considering the developed microwave-assisted real-time TGA-pyrolysis, which can enhance the efficiency and sustainability of plastic waste recycling processes.