Barlucchi Leonardo, Biale Greta, La Nasa Jacopo, Mattonai Marco, Pezzini Stefano, Corti Andrea, Castelvetro Valter, Modugno Francesca
Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, Italy.
Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, Italy; Centre for Instrument Sharing, University of Pisa, Pisa, Italy.
Sci Total Environ. 2024 Dec 1;954:176832. doi: 10.1016/j.scitotenv.2024.176832. Epub 2024 Oct 9.
Microplastics (MPs) are considered one of the most widespread pollutants in all ecosystems worldwide. In the environment, MPs can undergo hydrolysis and/or oxidation, resulting in the release of low-molecular weight degradation products, along with additives, and adsorbed organic pollutants. In this study, the morphological, chemical, and thermal changes of microplastics obtained from two biodegradable plastics, polylactic acid and Mater-Bi®, and a recycled plastic, recycled-polyethylene terephthalate, were examined after accelerated ageing under photo-oxidative conditions in synthetic seawater in a Solarbox system, and after thermal treatment in the dark. Thermal properties were studied by thermogravimetric analysis, differential scanning calorimetry, and evolved gas analysis-mass spectrometry. Compositions and changes of chemical components of the polymers were evaluated by attenuated total reflection-Fourier transform infrared spectroscopy and pyrolysis-gas chromatography-mass spectrometry. The leachable fractions and degradation products released in synthetic seawater by degraded MPs were characterized by gas chromatography-mass spectrometry. This study allowed us to identify hydrolysis as the main degradation pathway of the polymers under analysis, and to characterize not only the oligomers and degradation products released in the water as a consequence of degradation, but also additives used in plastic item formulations. This study improves our understanding of these polymers' behavior under accelerated ageing conditions.
微塑料（MPs）被认为是全球所有生态系统中分布最广泛的污染物之一。在环境中，微塑料会发生水解和/或氧化，导致低分子量降解产物、添加剂以及吸附的有机污染物的释放。在本研究中，对从两种可生物降解塑料聚乳酸和 Mater - Bi® 以及一种回收塑料回收聚对苯二甲酸乙二酯中获得的微塑料，在 Solarbox 系统的合成海水中进行光氧化条件下的加速老化后，以及在黑暗中进行热处理后，其形态、化学和热变化进行了研究。通过热重分析、差示扫描量热法和逸出气体分析 - 质谱法研究热性能。通过衰减全反射 - 傅里叶变换红外光谱和热解 - 气相色谱 - 质谱法评估聚合物化学成分的组成和变化。用气相色谱 - 质谱法对降解后的微塑料在合成海水中释放的可浸出部分和降解产物进行表征。本研究使我们能够确定水解是所分析聚合物的主要降解途径，不仅能够表征因降解而在水中释放的低聚物和降解产物，还能表征塑料制品配方中使用的添加剂。本研究增进了我们对这些聚合物在加速老化条件下行为的理解。
