School of Civil and Environmental Engineering, University of Technology, Post Box 129, Broadway, Sydney, NSW 2007, Australia; CRC CARE, PO Box 486, Salisbury, SA 5106, Australia.
School of Civil and Environmental Engineering, University of Technology, Post Box 129, Broadway, Sydney, NSW 2007, Australia; Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, 27 Shanda South Road, Jinan 250100, People's Republic of China.
J Hazard Mater. 2015 Mar 2;284:190-200. doi: 10.1016/j.jhazmat.2014.11.003. Epub 2014 Nov 8.
Adsorption of natural organic matter, aggregation and disaggregation have been identified as three of the main processes affecting the fate and behaviour of engineered nanoparticles (ENPs) in aquatic environments. However, although several methods have been developed to study the aggregation behaviour of ENPs in natural waters, there are only a few studies focusing on the fate of such aggregates and their potential disaggregation behaviour. In this study, we proposed and demonstrated a simple method for characterising the aggregation behaviour and aggregate structure of ENPs in different natural waters. Both the aggregate size of ENPs and their adsorption capacity for dissolved organic matter (DOM) were strongly related (R(2)>0.97, p<.05) to the combined effect of initial concentration of dissolved organic matter (DOM) and the ionic strength of the natural waters. The structure of the formed aggregates was strongly correlated (R(2)>0.95, p<.05) to the amount of DOM adsorbed by the ENPs during the aggregation process. Under high ionic strength conditions, aggregation is mainly governed by diffusion and the aggregates formed under these conditions showed the lowest stability and fractal dimension, forming linear, chain-like aggregates. In contrast, under low ionic strength conditions, the aggregate structure was more compact, most likely due to strong chemical binding with DOM and bridging mechanisms involving divalent cations formed during reaction-limited aggregation.
天然有机物的吸附、聚集和分散已被确定为影响水环境污染工程纳米粒子（ENPs）命运和行为的三个主要过程。然而，尽管已经开发了几种方法来研究天然水中 ENPs 的聚集行为，但只有少数研究关注这些聚集体的命运及其潜在的分散行为。在这项研究中，我们提出并证明了一种简单的方法来描述不同天然水中 ENPs 的聚集行为和聚集结构。ENPs 的聚集大小及其对溶解有机物（DOM）的吸附能力与溶解有机物（DOM）的初始浓度和天然水的离子强度的综合效应密切相关（R(2)>0.97，p<.05）。形成的聚集物的结构与 ENPs 在聚集过程中吸附的 DOM 量密切相关（R(2)>0.95，p<.05）。在高离子强度条件下，聚集主要由扩散控制，在这些条件下形成的聚集物稳定性和分形维数最低，形成线性、链状聚集物。相比之下，在低离子强度条件下，聚集物的结构更加紧密，这很可能是由于与 DOM 发生强烈的化学结合以及在反应限制聚集过程中形成的二价阳离子的桥接机制所致。
