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New sight of microplastics aging: Reducing agents promote rapid aging of microplastics under anoxic conditions

Journal of Hazardous Materials 2023 58 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count. Score: 50 ? 0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.
Chuanqi Xiao, Mengwei Zhang, Mengwei Zhang, Ling Ding, Xinran Qiu, Xuetao Guo

Summary

Researchers discovered that reducing agents can promote rapid aging of microplastics under oxygen-free conditions, demonstrating that PET microplastics underwent significant chemical changes when exposed to reducing agents like sodium borohydride within just seven days.

Polymers

The aging of microplastics (MPs) occurs extensively in the environment, and understanding the aging mechanisms of MPs is essential to study the properties, fate and environmental impact of MPs. We proposed a creative hypothesis that polyethylene terephthalate (PET) can be aged by reducing reactions with reducing agents. Simulation experiments based on the principle of reduction of carbonyl by NaBH were conducted to test the correctness of this hypothesis. The results showed that after 7 days of experiments, physical damage and chemical transformation occurred in the PET-MPs. The particle size of MPs was reduced by 34.95-55.93 %, and the C/O ratio was increased by 2.97-24.14 %. The changing order of surface functional groups (CO > C-O > C-H > C-C) was obtained. The occurrence of reductive aging and electron transfer of MPs was further supported by electrochemical characterization experiments. These results together reveal the reductive aging mechanism of PET-MPs: CO is firstly reduced to C-O by BH attack, and then further reduced to ·R. The resulting ·R recombines to form new C-H and C-C. This study is beneficial to deepen the understanding of the chemical aging of MPs, and can provide a theoretical basis for further research on the reactivity of oxygenated MPs with reducing agents.

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