Department of Civil and Environmental Engineering and Geodetic Science, The Ohio State University, Columbus, Ohio 43210, United States.
Langmuir. 2010 Nov 16;26(22):16690-8. doi: 10.1021/la101768n. Epub 2010 Sep 29.
Bare silver nanoparticles with diameters of 82 ± 1.3 nm were synthesized by the reduction of the Ag(NH(3))(2)(+) complex with D-maltose, and their morphology, crystalline structure, UV-vis spectrum, and electrophoretic mobilities were determined. Dynamic light scattering was employed to assess early stage aggregation kinetics by measuring the change in the average hydrodynamic diameter of the nanoparticles with time over a range of electrolyte types (NaCl, NaNO(3), and CaCl(2)) and concentrations. From this the critical coagulation concentration values were identified as 30, 40, and 2 mM for NaNO(3), NaCl, and CaCl(2), respectively. Although the silver nanoparticles were observed to dissolve in all three electrolyte solutions, the aggregation results were still consistent with classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The dissolution of the silver nanoparticles, which were coated with a layer of Ag(2)O, was highly dependent on the electrolyte type and concentration. In systems with Cl(-) a secondary precipitate, likely AgCl, also formed and produced a coating layer that incorporated the silver nanoparticles. Aggregation of the silver nanoparticles was also examined in the presence of Nordic aquatic fulvic acid and was little changed compared to that evaluated under identical fulvic acid-free conditions. These results provide a fundamental basis for further studies evaluating the environmental fate of silver nanoparticles in natural aquatic systems.
通过还原 Ag(NH(3))(2)(+) 配合物与 D-麦芽糖,合成了直径为 82 ± 1.3nm 的裸露银纳米粒子,并对其形态、晶体结构、紫外-可见光谱和电泳迁移率进行了测定。通过测量纳米粒子在不同电解质类型(NaCl、NaNO(3)和 CaCl(2))和浓度下随时间变化的平均水动力直径,采用动态光散射评估早期聚集动力学。从这一结果中,可以确定 NaNO(3)、NaCl 和 CaCl(2)的临界聚沉浓度值分别为 30、40 和 2mM。尽管观察到银纳米粒子在所有三种电解质溶液中都溶解,但聚集结果仍与经典的德加古因-兰德奥韦-奥弗贝克(DLVO)理论一致。银纳米粒子的溶解,它们被一层 Ag(2)O 所覆盖,高度依赖于电解质的类型和浓度。在含有 Cl(-)的体系中,也形成了二次沉淀,可能是 AgCl,并产生了一个包含银纳米粒子的涂层。在存在北欧水生腐殖酸的情况下,也对银纳米粒子的聚集进行了研究,与在相同无腐殖酸条件下的评估相比,聚集程度变化不大。这些结果为进一步研究在自然水生态系统中评估银纳米粒子的环境归宿提供了基础。