The increasing use of manufactured nanomaterials (MNMs) and their inevitable release into the environment, especially via wastewater treatment plants (WWTPs), poses a potential threat for aquatic organisms. The characterization of MNMs with analytical tools to comprehend their fate and effect on the ecosystem is hence of great importance for environmental risk assessment. We herein report, for the first time, the investigation of physicochemical transformation processes during artificial wastewater treatment of silver (Ag-NPs) and titanium dioxide nanoparticles (TiO₂-NPs) via selected area electron diffraction (SAED). TiO₂-NPs with an anatase/rutile ratio of ∼80/20 were found to not undergo any physicochemical transformation, as shown via previous energy-dispersive X-ray analysis (EDX) elemental mapping and crystal structure analysis via SAED. In contrast, Ag-NPs were colocalized with substantial amounts of sulfur (Ag/S ratio of 1.9), indicating the formation of Ag₂S. SAED ultimately proved the complete transformation of face-centered cubic (fcc) Ag-NPs into monoclinic Ag₂S-NPs. The size distribution of both nanomaterials remained virtually unchanged. Our investigations show that cloud point extraction of NPs and their subsequent crystal structure analysis via SAED is another valuable approach toward the comprehensive investigation of wastewater-borne MNMs. However, the extraction procedure needs optimization for environmentally low NP concentrations.

中文翻译：

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通过选择区域电子衍射研究模型废水中的银和二氧化钛纳米颗粒的命运。

人造纳米材料（MNMs）的使用不断增加以及不可避免地释放到环境中，尤其是通过废水处理厂（WWTP）释放到环境中，对水生生物构成了潜在威胁。因此，使用分析工具来表征多边生物的特征，以了解其命运和对生态系统的影响，对于环境风险评估至关重要。我们在此首次报告了通过选定区域电子衍射（SAED）对银（Ag-NPs）和二氧化钛纳米颗粒（TiO ₂ -NPs）进行人工废水处理期间的物理化学转化过程的研究。二氧化钛₂如先前的能量色散X射线分析（EDX）元素图谱和通过SAED进行的晶体结构分析所示，锐钛矿/金红石比约为80/20的-NP被发现没有发生任何物理化学转化。与此相反，银纳米颗粒，用大量的硫的（1.9的Ag / S比）共定位，表明银的形成₂ S. SAED最终证明面心立方（fcc）的Ag-NP的完全转变为单斜的Ag ₂S-NP。两种纳米材料的尺寸分布实际上保持不变。我们的研究表明，通过SAED对NP进行浊点提取和随后的晶体结构分析是对废水中MNM进行综合研究的另一种有价值的方法。但是，提取程序需要针对环境中低的NP浓度进行优化。