Sustainable management of medical plastic waste through carbon dioxide-assisted pyrolysis

• Published in: Chemosphere (Oxford) 2024-09, Vol.364, p.143266, Article 143266
• Main Authors: Kim, Jee Young, Park, Jonghyun, Lee, Dong-Jun, Choi, Ye-Bin, Kwon, Eilhann E.
• Format: Article
• Language: English
• Subjects: biological hazards; carbon; carbon dioxide; catalysts; Circular economy; CO2 utilization; energy; Medical plastic waste; nitrogen; Plastic valorization; poly(vinyl chloride); polypropylenes; polystyrenes; pyrolysis; toxicity; Waste-to-energy; wastes
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2024.143266

To address the challenges associated with medical plastic waste and to characterize its heterogeneity, non-recyclability, and potential biohazard risks, this study explored a carbon dioxide (CO2)-assisted pyrolysis process as a sustainable disposal method. Medical plastic waste typically includes polypropylene, polystyrene, and polyvinyl chloride. To experimentally evaluate the functional reactivity of CO2, we employed three pyrolysis setups (one-stage, two-stage, and catalytic processes). The technical advantages of using CO2 over inert gases such as nitrogen (N2) were demonstrated through pyrolysis tests. The results showed that energy production was enhanced under CO2 conditions, with catalytic pyrolysis generating 146% more flammable gases compared to pyrolysis in an N2 environment. The use of CO2 also led to a reduction in the formation of toxic chemicals due to improved thermal cracking. The CO2-assisted pyrolysis process exhibited net negative CO2 emissions when a catalyst was present, as a substantial amount of CO2 was consumed during the process. In conclusion, CO2-assisted pyrolysis of medical plastic waste offers a sustainable management solution that maximizes the utilization of carbon resources. [Display omitted] •Medical waste was composed of PP (44.5 wt%), PS (14.1 wt%), and PVC (41.4 wt%).•Catalytic pyrolysis was employed to valorize mixed plastic medical waste.•Energy production was higher in pyrolysis under CO2 compared to N2 (146% increase).•The generation of toxic chemicals was reduced in CO2-assisted pyrolysis.•813 kg of CO2 consumed when processing 1 ton of medical waste.