Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Sci Total Environ. 2020 Apr 20;714:136862. doi: 10.1016/j.scitotenv.2020.136862. Epub 2020 Jan 21.
Most microplastics (MPs) have undergone extensive aging in the environment. Aged MPs exhibit different physical and chemical properties from unaged ones. Here, we studied the effects of accelerated aging on the characteristics and pyrolysis of commercial pigmented MPs, as well as pigments leaching and their interactions in simulated gastric and intestinal fluids of mammals. We report that the carbonyl index, surface area, and color change of MPs increased after aging treatment. Cracks and fragmentation of MPs facilitated the accessibility of light and oxygen to internal layer and therefore accelerated the aging process. TGA/GC-MS analysis showed that the high temperature resistance of MPs decreased after aging. Thermal decomposition of pigments and polyethylene occurred in temperature ranges of 340-406 °C and 406-550 °C, respectively. Mono (di)-alkenes and saturated alkanes were the thermal decomposition products of polyethylene. Aging of MPs also caused an increased release of pigments and prolonged aging time led to more release in simulated fluids. Pigments would result in fluorescence quenching of the enzymes through binding interactions once they were released from MPs into simulated fluids. Charge neutralization and polymer bridging accounted for the formation of pigment-enzyme complexes and flocs. These novel findings will allow us to better assess how aging process affects the characteristics, leaching, and toxicity of MPs.
大多数微塑料（MPs）在环境中经历了广泛的老化。老化的 MPs 表现出与未老化的 MPs 不同的物理和化学性质。在这里，我们研究了加速老化对商业着色 MPs 的特性和热解的影响，以及哺乳动物模拟胃液和肠液中颜料的浸出及其相互作用。我们报告说，老化处理后 MPs 的羰基指数、表面积和颜色变化增加。MPs 的裂缝和碎裂使光和氧气更容易进入内层，从而加速了老化过程。TGA/GC-MS 分析表明，老化后 MPs 的耐高温性降低。颜料和聚乙烯的热分解分别发生在 340-406°C 和 406-550°C 的温度范围内。单（二）烯烃和饱和烷烃是聚乙烯的热分解产物。MPs 的老化也导致颜料释放增加，老化时间延长导致模拟液中释放更多的颜料。一旦颜料从 MPs 释放到模拟液中，它们就会通过结合相互作用导致酶的荧光猝灭。电荷中和和聚合物桥接解释了颜料-酶复合物和絮体的形成。这些新发现将使我们能够更好地评估老化过程如何影响 MPs 的特性、浸出和毒性。
