The Reactivity of Polyethylene Microplastics in Water under Low Oxygen Conditions Using Radiation Chemistry
The Reactivity of Polyethylene Microplastics in Water under Low Oxygen Conditions Using Radiation Chemistry
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DOI：
10.3390/w13213120
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发表时间：
2021-11
期刊：
影响因子：
3.4
通讯作者：
J. Peller;S. Mezyk;Sarah Shidler;Joe Castleman;Scott Kaiser;Gregory P. Horne
中科院分区：
文献类型：
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作者：
J. Peller;S. Mezyk;Sarah Shidler;Joe Castleman;Scott Kaiser;Gregory P. Horne
聚乙烯（PE）是一种广泛使用的聚合物，因此导致其成为常见的环境污染物。众所周知，聚乙烯和其他塑料废物在地表沃茨中具有高度持久性;然而，随着时间的推移，化学和物理变化确实会发生，主要取决于高度可变的自然条件，如氧气（O2）的可用性。伽马辐射用于在最初充气的水溶液中产生活性氧物质，即羟基自由基，以模拟微塑料在沃茨中的自然风化，其中溶解的O2存在波动并且经常耗尽。使用固相微萃取（SPME）纤维结合气相色谱-质谱（GCMS），对辐照含PE溶液的顶空进行探测，以确定降解产物的形成。检测到的主要物质是正十二烷，以及痕量的十三烷、2-十二酮和十六烷，据信这些物质主要吸附在PE微塑料中，超过其水溶性限度。通过拉曼光谱以及光场和暗场显微镜进行的表面表征表明，在低氧至厌氧条件下，辐照PE微塑料的化学组成没有变化。然而，观察到形态学变化，表明自由基结合反应。
Polyethylene (PE) is an intensely utilized polymer, which has consequently led to it becoming a common environmental contaminant. PE and other plastic waste are known to be highly persistent in surface waters; however, chemical and physical changes do take place over time, dependent mostly on highly variable natural conditions, such as oxygen (O2) availability. Gamma radiation was used to generate reactive oxygen species, namely hydroxyl radicals, in initially aerated aqueous solutions to simulate the natural weathering of microplastics in waters where there are fluctuations and often depletions in dissolved O2. The headspace of the irradiated PE-containing solutions was probed for the formation of degradation products using solid-phase microextraction (SPME) fibers in combination with gas chromatography mass spectrometry (GCMS). The major species detected were n-dodecane, with trace levels of tridecane, 2-dodecanone, and hexadecane, which were believed to be predominately adsorbed in the PE microplastics in excess of their aqueous solubility limits. Surface characterization by Raman spectroscopy and light and dark field microscopy indicated no change in the chemical composition of the irradiated PE microplastics under low O2 to anaerobic conditions. However, morphological changes were observed, indicating radical combination reactions.