Enhanced sorption of the UV filter 4-methylbenzylidene camphor on aged PET microplastics from both experimental and theoretical perspectives. Issue 51 (1st October 2021)

• Record Type: Journal Article
• Authors: Shih, Chun-Yu; Wang, Yu-Hsiang; Chen, Yi-Ju; Chen, Hsin-An; Lin, Angela Yu-Chen
• Is Part Of: RSC advances. Volume 11:Issue 51(2021)
• Page Start: 32494
• Page End: 32504
• Publication Date: 2021-10-01
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d1ra05013c
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The enhanced sorption behavior of aged polyethylene terephthalate (PET) microplastics with 4-methylbenzylidene-camphor (4MBC) via hydrogen bonding is investigated through both experimental and theoretical methods. Abstract : In this study, the morphology and sorption behavior of polyethylene terephthalate (PET) microplastics during the aging process are investigated. To clarify the sorption mechanism of aged PET microplastics, the common sunblock 4-methylbenzylidene camphor (4-MBC) was chosen as the target contaminant, and UV irradiation was used for the laboratory aging simulation. The results show that oxygen-containing functional groups (carboxylic, carbonyl, ketone and hydroxyl groups) increase on the surface of aged PET microplastics. Based on density functional theory (DFT) simulations, the camphor part of 4-MBC acts as a hydrogen bond acceptor, whereas the carboxylic group on aged PET microplastics acts as a hydrogen bond donor. The formation of hydrogen bonding causes increased sorption of 4-MBC on aged PET microplastics. The sorption capacity increased from 5 to 11 μg g −1 for 50 ppb 4-MBC with 100 mg PET microplastics after a five-day aging process. Other environmental factors that affect sorption were also identified; a higher pH value and the presence of salinity reduced the amount of sorption. The sorption of virgin PET ranged from 8.0 to 3.4 μg g −1 and the sorption of aged PET ranged from 22 to 5 μg g −1 at pH 4 to 10. In the presence of salinity (10% seawater), the virgin PET sorption dropped to 2.1 μg g −1 while the aged PET sorption dropped to 4 μg g −1 . A similar phenomenon was also observed in the sorption behavior under natural sunlight (the sorption of PET increased from 0.4 to 0.8 μg g −1 after 6 months of aging). The potential risk to ecosystems of aged PET microplastics under prolonged sunlight exposure in the natural environment could be greater than that predicted for virgin microplastics.