The First Observation of the Formation of Persistent Aminoxyl Radicals and Reactive Nitrogen Species on Photoirradiated Nitrogen-Containing Microplastics
The First Observation of the Formation of Persistent Aminoxyl Radicals and Reactive Nitrogen Species on Photoirradiated Nitrogen-Containing Microplastics
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首次观察到光照射的含氮微塑料上持久性氨氧基自由基和活性氮的形成
DOI：
10.1021/acs.est.1c05650
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Lingyan Zhu
中科院分区：
文献类型：
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作者：
Kecheng Zhu;Hanzhong Jia;Wenjun Jiang;Yajiao Sun;Chi Zhang;Ze Liu;Tiecheng Wang;Xuetao Guo;Lingyan Zhu
含氮微塑料（N-MP）广泛存在于大气中，但其潜在的健康风险却被忽视了。在这项研究中，持久性氨基氧自由基（PAORs）和活性氮物种（RNS）的N-MP光照射下的形成进行了研究。光老化后，各向异性的三重态的g-因子为1.22.0044，对应于PAORs，检测到的非芳香族聚酰胺（PA），而不是氨基树脂（AmR）的电子顺磁共振和密度泛函理论计算证实。使用X-射线光电子能谱和拉曼光谱，这被认为是PAOR的主要结构基础/前体的光老化PA上产生的氧化胺部分进行了鉴定。令人惊讶的是，在辐照的PA上也观察到RNS。硝酮基团光解产生的·NO同时与过氧化自由基和O2·-反应，分别生成·NO2和过氧亚硝酸根，生成过氧酰基硝酸酯（PAN）和CO 3·-。此外，老化PA的氧化电位和还原电位均显著高于AmR，这分别归因于老化PA中含有丰富的RNS、有机氢过氧化物和PANs，以及PAOR较强的电子转移能力。这项工作提供了重要的信息，空气中的N-MP的潜在风险，并可能作为未来的毒理学评估的指导。
Nitrogen-containing microplastics (N-MPs) are widely present in the atmosphere, but their potential health risks have been overlooked. In this study, the formation of persistent aminoxyl radicals (PAORs) and reactive nitrogen species (RNSs) on the N-MPs under light irradiation was investigated. After photoaging, an anisotropic triplet with the g-factor of ∼2.0044, corresponding to PAORs, was detected on the nonaromatic polyamide (PA) rather than amino resin (AmR) by electron paramagnetic resonance and confirmed by density functional theory calculations. The generated amine oxide portions on the photoaged PA were identified using X-ray photoelectron spectroscopy and Raman spectroscopy, which were considered to be the main structural basis/precursors of a PAOR. Surprisingly, RNSs were also observed on the irradiated PA. The generated ·NO due to the aphotolysis of nitrone groups simultaneously reacted with peroxide radicals and O2·–to yield ·NO2and peroxynitrite, respectively, which were responsible for peroxyacyl nitrates (PAN) and CO3·–formation. Besides, a significantly higher oxidative potential and reductive potential were observed for the aged PA than AmR, which is assigned to the abundant RNSs, organic hydroperoxides and PANs, and a strong ability to transfer electrons from PAOR, respectively. This work provides important information for the potential risks of airborne N-MPs and may serve as a guide for future toxicological assessments.