Synergistic effects of CO2 on complete thermal degradation of plastic waste mixture through a catalytic pyrolysis platform: A case study of disposable diaper

• Published in: Journal of hazardous materials 2021-10, Vol.419, p.126537-126537, Article 126537
• Main Authors: Kwon, Dohee, Jung, Sungyup, Lin, Kun-Yi Andrew, Tsang, Yiu Fai, Park, Young-Kwon, Kwon, Eilhann E.
• Format: Article
• Language: English
• Subjects: Catalytic pyrolysis; Circular economy; CO2; Diaper; Plastic management; Waste-to-energy
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.126537

Consumption of diverse plastics has posed an environmental threat because their disposal practices, landfilling and incineration, release toxic chemicals and microplastics into all environmental media. Indeed, heterogeneous matrix of plastic wastes makes them hard to be disposed. As such, this study aimed to introduce an environmentally benign/reliable disposal platform for complete decomposition of plastic wastes. Pyrolysis process was adapted to convert plastics into syngas, and a disposable diaper (DD) was used as model plastic waste, because it is composed of a variety of polymeric materials. Pyrolysis of DD resulted in the formation of gaseous products and pyrogenic oils, composed of (oxygenated) hydrocarbons. Nonetheless, reactivity of CO2 as an oxidant in pyrolysis of DD was negligible. To impart the strong/desired reactivity of CO2, Ni-based catalyst was adopted. Ni catalyst enhanced H2 and CO formations 4 and 15 times more than pyrolysis without catalyst at 700 °C under CO2. The value-added syngas production was originated from the reduction of polymeric waste, and its derivatives including aromatic compounds. Thus, CO2 offered a strategic means to produce value-added chemicals and reduce aromaticity of pyrogenic products. The observations could offer an innovative way to control the fate of toxic chemicals derived from plastic pyrolysis. [Display omitted] •Identification of the type of plastic in disposable waste was confirmed.•A reliable disposal platform for plastic wastes was introduced.•Synergistic effect of CO2 on complete thermal destruction of plastics was confirmed.•CO2 acted as an oxidant for conversion of plastics into value-added chemicals.•In the presence of Ni-based catalyst, the effectiveness of CO2 was greatly enhanced.