Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
J Hazard Mater. 2024 Dec 5;480:136418. doi: 10.1016/j.jhazmat.2024.136418. Epub 2024 Nov 5.
Understanding the photoaging dynamics of biodegradable and conventional microplastics (MPs) is crucial due to their widespread environmental risks. However, studies on the photoaging behaviors of different MPs in soil ecosystems are limited. This study focused on two representative MPs, conventional polyethylene (PE) and biodegradable poly(butylene adipate-co-terephthalate) (PBAT), examining their photoaging processes in soil. The photoaging performance of these MPs was characterized using indicators like carbonyl index (CI), oxygen-carbon ratio (O/C), weight loss (WL), and water contact angle (CA). The entropy weight method (EWM) was employed to calculate a comprehensive aging index (CAI), quantitatively measuring overall photoaging. The results revealed that PBAT underwent significantly greater photoaging than PE, with the CAI of aged PBAT (0.88) being over 15 times higher than that of aged PE (0.06). Environmental persistent free radicals (EPFRs) were identified as key factors in MPs' photoaging. LC-MS/MS analysis revealed oxygen-containing byproducts and plastic additives, suggesting photodegradation pathways involving chain scission and oxidation. Density functional theory (DFT) highlighted differences in energy gaps and susceptibility to free radical attacks between PE and PBAT. This study not only compares photoaging behaviors but also introduces a novel method for evaluating MPs' aging, providing a basis for assessing ecological risks in soil.
理解可生物降解和传统微塑料（MPs）的光老化动态至关重要，因为它们存在广泛的环境风险。然而，关于不同 MPs 在土壤生态系统中光老化行为的研究有限。本研究聚焦于两种代表性的 MPs，即传统聚乙烯（PE）和可生物降解聚（丁二酸丁二醇酯-对苯二甲酸酯）（PBAT），研究它们在土壤中的光老化过程。使用羰基指数（CI）、氧碳比（O/C）、失重（WL）和水接触角（CA）等指标来表征这些 MPs 的光老化性能。采用熵权法（EWM）计算综合老化指数（CAI），定量衡量整体光老化。结果表明，PBAT 的光老化程度明显大于 PE，老化后的 PBAT 的 CAI（0.88）是老化后 PE 的 CAI（0.06）的 15 倍以上。环境持久性自由基（EPFRs）被确定为 MPs 光老化的关键因素。LC-MS/MS 分析揭示了含氧副产物和塑料添加剂，表明存在涉及链断裂和氧化的光降解途径。密度泛函理论（DFT）突出了 PE 和 PBAT 之间的能隙和对自由基攻击的敏感性差异。本研究不仅比较了光老化行为，还引入了一种评估 MPs 老化的新方法，为评估土壤中的生态风险提供了依据。
