可生物降解微塑料的自然光解老化  

Natural photo-aging of biodegradable microplastics

作　　者：白利华 梁思嘉 董若辰 徐舒霞 顾馨悦 朱凤晓 王超[1] 谷成[1] BAI Lihua;LIANG Sijia;DONG Ruochen;XU Shuxia;GU Xinyue;ZHU Fengxiao;WANG Chao;GU Cheng(State Key Laboratory of Pollution Control and Resource Reuse,School of Environment,Nanjing University,Nanjing,210023,China;School of Environment,Nanjing Normal University,Nanjing,210023,China)

机构地区：[1]污染控制与资源化研究国家重点实验室,南京大学环境学院,南京210023 [2]南京师范大学环境学院,南京210023

出　　处：《环境化学》2022年第12期3831-3839,共9页Environmental Chemistry

基　　金：国家自然科学基金(22276091,42277031)资助。

摘　　要：近年来,微塑料(MPs)污染问题受到人们的广泛关注.可生物降解塑料被认为是常规的不可生物降解塑料的替代品,其产量和环境检出量显著增加.MPs的老化过程具有显著的环境行为和生态效应,而光照辐射在塑料老化和降解过程中起到主要作用.然而,现有研究对可生物降解微塑料的自然光解老化过程及其机理的研究鲜有报道.因此,本研究选取了4种常见的可生物降解微塑料为实验对象,分别为聚乳酸(PLA)、聚羟基脂肪酸酯(PHA)、聚丁二酸丁二醇酯(PBS)和聚对苯二甲酸-己二酸丁二酯(PBAT),旨在探究上述4种可生物降解微塑料在自然和模拟光照下的老化过程及潜在机理.通过自然和模拟光解老化实验,利用傅立叶变换红外光谱(FTIR)和电子顺磁共振波谱(EPR)观察4种塑料在老化过程中旧键断裂和新键生成,发现在56 d的光老化过程中,PLA-MPs和PBS-MPs表面官能团含量并无显著变化,而随着老化时间的增加,PHA-MPs表面—C=C—的数量在增加,PBAT表面—C—O和C=O的数量在增加.除了实验结果之外,分子模型构建和红外光谱计算等理论分析也为可降解MPs的自然光老化机理提供了理论支撑.Over the recent past years,microplastics(MPs)have raised widespread public attention due to their potential environmental and health risks.In order to eliminate the environmental burden of plastics,biodegradable plastics are industrially produced and recognized as an alternative to conventional non-biodegradable plastics.While,vast production and consumption inevitably led to their widespread distributions in various environmental matrices.The aging effect could significantly change physiochemical properties and subsequent environmental behaviors of MPs.Amongst various aging treatments,light radiation plays a dominant role in MP formation and degradation.However,few studies have been conducted to investigate the natural photo-aging process and mechanism of biodegradable MPs.Therefore,four commonly used biodegradable MPs were selected in the present study,i.e.,polylactic acid(PLA),polyhydroxyalkanoate(PHA),polybutylene succinate(PBS)and polyparaben phthalic acid-butylene adipate(PBAT),which were employed to explore the aging process and underlying mechanism of biodegradable microplastics under natural and simulated solar irradiation.Moreover,Fourier transform infrared spectroscopy(FTIR)and electron paramagnetic resonance spectroscopy(EPR)were used to monitor the breakage and formation of bonds during the aging process.It was found that the content of functional groups on the surface of PLA-MPs and PBS-MPs did not change significantly during the 56 d photoaging process,while the amount of—C=C—on the surface of PHA-MPs and the amount of—C—O and C=O on the surface of PBAT increased with the lengthening irradiation time.In addition to experimental results,the theoretical analysis including molecular model construction and infrared spectra calculation were performed to support the photo-aging mechanism of degradable MPs.

关 键 词：可生物降解微塑料 光老化 原位红外光谱 原位电子顺磁共振波谱 

分 类 号：X505[环境科学与工程—环境工程]