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Pyrolysis of Polypropylene and Nitrile PPE Waste: Insights into Oil Composition, Kinetics, and Steam Cracker Integration

Materials Today Communications 2025 1 citation ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Ross Baird, Raffaella Ocone, Aimaro Sanna

Summary

Researchers pyrolyzed mixtures of disposable surgical masks and nitrile gloves and found that peak condensable oil yields of 77% occur at 600°C, producing predominantly aliphatic hydrocarbons in the diesel range, though the oil requires pre-treatment to meet industrial steam cracker standards.

Polymers

In this study, non-isothermal pyrolysis of a mixture of disposable surgical face masks (FMs) and nitrile gloves (NGs) was conducted, using a heating rate of 100 °C/min, N2 flowrate of 100 mL/min, and temperatures between 500 and 800 °C. Condensable product yield peaked at 600 °C (76.9 wt.%), with gas yields rising to 31.0 wt.%, at 800 °C. GC-MS of the condensable product confirmed the presence of aliphatic compounds (>90%), while hydrogen, methane, and ethylene dominated the gas composition. At 600 °C, gasoline (C4 to C12)-, diesel (C13 to C20)-, motor oil (C21 to C35)-, and heavy hydrocarbon (C35+)-range compounds accounted for 23.7, 46.7, 12.5, and 17.1%, of the condensable product, respectively. Using model-free methods, the average activation energy and pre-exponential factor were found to be 309.7 ± 2.4 kJ/mol and 2.5 ± 3.4 × 1025 s-1, respectively, while a 2-dimensional diffusion mechanism was determined. Scale-up runs confirmed high yields of condensable product (60-70%), with comparable composition to that obtained from lab-scale tests. The pyrolysis oil exceeds acceptable oxygen, nitrogen, chlorine, and fluorine levels for industrial steam crackers-needing pre-treatment-while other contaminants like sulphur and metals could be managed through mild blending. In summary, this work offers a sustainable approach to address the environmental concerns surrounding disposable FMs and NGs.

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