Abstract
The widespread use of surgical masks made of polyolefin and face shields made of polyester during pandemics contributes significantly to plastic pollution. An eco-friendly approach to process plastic waste is using supercritical water, but the reaction of mixed polyolefin and polyester in this solvent is not well understood, which hinders practical applications. This study aimed to investigate the reaction of waste surgical masks (SM) and face shields (FS) mixed in supercritical water. Results showed that the optimal treatment conditions were 400 °C and 60 min, achieving a liquid oil yield of 823.03 mg·g−1 with 25 wt% FS. The interaction between polypropylene (PP), polyethylene terephthalate (PET), and iron (Fe) in SM and FS mainly determined the production of liquid oil products such as olefins and benzoic acid. The methyl-branched structure of PP enhanced PET hydrolysis, resulting in higher production of terephthalic acid (TPA). The degradation of PP was facilitated by the acidic environment created by TPA and benzoic acid in the reaction. Moreover, the hydrolysis of PET produced carboxylic acid, which coordinated with Fe3+ to form Fe-H that catalyzed the polymerization of small olefins, contributing to higher selectivity for C9 olefins. Therefore, this study provides valuable insights into the degradation mechanism of mixed PPE waste in supercritical water and guidance for industrial treatment.
Original language | English |
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Article number | 132338 |
Number of pages | 13 |
Journal | Journal of Hazardous Materials |
Volume | 459 |
Early online date | 19 Aug 2023 |
DOIs | |
Publication status | Published - 5 Oct 2023 |
Bibliographical note
Funding Information:The study was supported by the LiaoNing Revitalization Talents Program [grant number: XLYC2007179 , XLYC2008012 ].
Publisher Copyright:
© 2023
Data Availability Statement
Data will be made available on request.Supplementary data associated with this article can be found in the online version at doi:10.1016/j.jhazmat.2023.132338.
Keywords
- Face shields
- Oil production
- Plastic wastes
- Supercritical water
- Surgical masks