Environmentally Relevant Freeze-Thaw Cycles Enhance the RedoxMediated Morphological Changes of Silver Nanoparticles
Environmentally Relevant Freeze-Thaw Cycles Enhance the RedoxMediated Morphological Changes of Silver Nanoparticles
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环境相关的冻融循环增强了银纳米颗粒的氧化还原介导的形态变化
DOI：
10.1021/acs.est.8b00694
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发表时间：
2018-06-19
影响因子：
11.4
通讯作者：
Liu, Jingfu
中科院分区：
文献类型：
--
作者：
Guo, Xiaoru;Yi, Yongguang;Liu, Jingfu
银纳米颗粒（AgNP）不可避免地被释放到自然系统中，特别是进入水生环境，在那里它们被氧化并释放Ag+，Ag+被还原回AgNP。环境冻融循环或冷冻可加速AgNPs与Ag+之间的动态转化。在此，冷冻处理引起的显着的形态变化进行了评估，通过紫外可见光谱和高分辨率透射电子显微镜，这表明还原再生，粒子融合，并发生聚结的AgNPs。此外，使用稳定的Ag同位素来跟踪AgNP氧化还原反应，该反应是圆形的，相对于在常温（4 ℃、25 ℃）下储存的颗粒的反应，在冷冻和冻融循环下加速。此外，天然有机物被发现稳定的颗粒形态。Ca ~（2+）和Cl ~-通过Ca ~（2+）诱导颗粒聚结和Cl ~-促进Ag ~+的还原，促进了冻融过程中颗粒的形态变化和氧化还原反应。这些物理化学变化也发生了环境相关浓度的银纳米粒子（50纳克L-1）在模拟的环境条件和自然水样冻融循环后。由于环境冻结条件引起的形态变化和氧化还原加速会显著影响AgNPs的流动性、生物利用度、毒性和环境归宿，因此在AgNPs的环境风险评估中应考虑冻融效应。
Silver nanoparticles (AgNPs) are inevitably released into natural systems, particularly into aquatic environments, where they are oxidized and release Ag+, which is reduced back to AgNPs. Environmental freeze-thaw cycles or freezing may accelerate the dynamic transformation between AgNPs and Ag+. Herein, the significant morphological changes caused by freezing treatments were assessed by UV-vis spectroscopy and high-resolution transmission electron microscopy, which revealed that reductive regeneration, particle fusion, and coalescence of the AgNPs occurred. In addition, a stable Ag isotope was used to track the AgNP redox reaction, which was round to be accelerated under freezing and freeze-thaw cycles relative to the reaction of particles stored at a normal temperature (4 degrees C, 25 degrees C). Furthermore, natural organic matter was found to stabilize the particle morphology. Ca2+ and Cl- intensified the morphological changes and redox reaction through Ca2+-induced particle coalescence and Cl--enhanced reduction of Ag+ during the freeze-thaw treatment. These physicochemical changes also occurred for an environmentally relevant concentration of AgNPs (50 ng L-1) in simulated environmental conditions and natural water samples after freeze-thaw cycles. Since the morphological changes and redox acceleration induced by environmental freezing conditions could dramatically influence the mobility, bioavailability, toxicity, and environmental fate of AgNPs, the freeze-thaw-induced effects should be considered'in the environmental risk assessment of AgNPs.