Division of Analytical Chemistry, Department of Chemistry, Technical University of Munich, Lichtenbergstraße 4, Garching, 85748, Germany.
Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (E), Munich, 81377, Germany.
Water Res. 2020 Mar 15;171:115399. doi: 10.1016/j.watres.2019.115399. Epub 2019 Dec 19.
Silver based nanoparticles (Ag-b-NPs) in the environment are of current concern as they may pose risks to human and environmental health, even at low concentration levels. It is widely known that Ag-b-NPs, once released from products containing these particles for antimicrobial reasons, can pass through wastewater treatment plants to some extent. These particles are transported via running waterways and eventually reach the sea. However, the fate of environmentally relevant ng L traces of Ag-b-NPs in seawater has not yet been sufficiently studied. Analytical techniques capable of determining these ultratraces of Ag-b-NPs in seawater are scarce and struggle furthermore with the high chloride content in highly saline matrices, such as seawater. In this study, we extracted Ag-b-NPs from matrices with varying salinity via cloud point extraction (CPE) and determined concentration and size of Ag-b-NPs in extracts with single particle inductively coupled plasma mass spectrometry (sp-ICP-MS). Applying this extraction and measurement technique, we were able to investigate the fate of Ag-b-NPs with different coatings (citrate and the predominant coatings in nature, silver sulfide and silver chloride) in matrices with increasing salinity and real seawater. All types of Ag-b-NPs were dissolved in all matrices almost independently of the chemical composition of the nanoparticles (NPs), whereas dissolution rates increased with increasing salinity due to the formation of soluble Ag(I) species and - in the presence of chloride - AgCl (x > 1) complexes. After an incubation time of not more than 72 h, Ag-b-NPs were dissolved almost completely. During the dissolution process, NP shrinkage could be clearly observed by sp-ICP-MS. Supplementary electron microscopy measurements revealed that the sulfur content in silver sulfide nanoparticles (AgS-NPs) increased during the dissolution process. Finally, we were able to investigate the dissolution process of real Ag-b-NPs in wastewater after increasing the salinity to seawater levels.
银基纳米粒子（Ag-b-NPs）在环境中受到关注，因为即使在低浓度水平下，它们也可能对人类和环境健康构成风险。众所周知，由于抗菌原因而从含有这些颗粒的产品中释放出的 Ag-b-NPs 可以在一定程度上通过废水处理厂。这些颗粒通过流水道运输，最终到达海洋。然而，环境相关 ng L 痕量的 Ag-b-NPs 在海水中的命运尚未得到充分研究。能够在海水中测定这些超痕量 Ag-b-NPs 的分析技术稀缺，并且在高盐度基质（如海水）中高氯含量方面也存在困难。在这项研究中，我们通过浊点萃取（CPE）从具有不同盐度的基质中提取 Ag-b-NPs，并使用单颗粒电感耦合等离子体质谱（sp-ICP-MS）测定提取物中 Ag-b-NPs 的浓度和粒径。应用这种提取和测量技术，我们能够研究具有不同涂层（柠檬酸盐和自然界中主要的涂层，硫化银和氯化银）的 Ag-b-NPs 在盐度增加的基质和实际海水中的命运。所有类型的 Ag-b-NPs 在所有基质中几乎都可以溶解，而与纳米颗粒（NPs）的化学成分无关，而由于可溶性 Ag(I)物种的形成以及在存在氯的情况下形成 AgCl(x>1)配合物，溶解速率随盐度的增加而增加。在不超过 72 小时的孵育时间内，Ag-b-NPs 几乎完全溶解。在溶解过程中，sp-ICP-MS 可以清楚地观察到 NP 收缩。补充电子显微镜测量表明，在溶解过程中，硫化银纳米颗粒（AgS-NPs）中的硫含量增加。最后，我们能够研究将废水的盐度增加到海水水平后，实际 Ag-b-NPs 的溶解过程。
