Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China.
Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.
J Colloid Interface Sci. 2015 Jul 15;450:272-278. doi: 10.1016/j.jcis.2015.03.027. Epub 2015 Mar 21.
Colloidal behavior of various nanoparticles (NPs) could be quite different under the influence of complicated water chemistry. Homoaggregations of four types of nanoparticles (NPs) were investigated with a focus on the effects of electrolyte ions, pH, and natural organic matter (NOM). Results show that critical coagulation concentrations (CCCs) of NaCl and CaCl2 for anatase TiO2, rutile TiO2, or CeO2 NPs were all inversely proportional to the valence of cations, following the Schulze-Hardy Rule, and homoaggregations of the three NPs were similarly inhibited by the presence of NOM within pH 3-9. Although the homoaggregation of Ag NPs was also increased as the concentration or valence of cations increased, the relationship between CCC and valence of the cations was far away from the Schulze-Hardy Rule; moreover, NOM only slightly increased CCC of CaCl2 and surprisingly decreased CCC of NaCl for Ag NPs. Excessively-adsorbed Cl(-) on the formed Ag-AgCl colloidal nucleus was detected, which could increase the electronegativity of Ag NPs and thus limit the aggregation effect of chlorides and the dispersion effect of NOM as well. These results are expected to increase our knowledge on the colloidal behavior and fate of NPs in aquatic environments.
在复杂的水化学影响下，各种纳米粒子（NPs）的胶体行为可能会有很大的不同。本研究聚焦于电解质离子、pH 值和天然有机物（NOM）的影响，研究了四种纳米粒子（NPs）的同质聚集。结果表明，锐钛矿 TiO2、金红石 TiO2 或 CeO2 NPs 的 NaCl 和 CaCl2 的临界聚沉浓度（CCC）均与阳离子的价数成反比，符合舒尔茨-哈迪规则，且在 pH 值 3-9 范围内，NOM 的存在同样抑制了三种 NPs 的同质聚集。尽管 Ag NPs 的同质聚集也随着阳离子浓度或价数的增加而增加，但 CCC 与阳离子价数之间的关系远非舒尔茨-哈迪规则；此外，NOM 仅略微增加了 CaCl2 的 CCC，而令人惊讶的是降低了 NaCl 对 Ag NPs 的 CCC。检测到在形成的 Ag-AgCl 胶核上过度吸附的 Cl(-)，这可能会增加 Ag NPs 的电负性，从而限制氯化物的聚集效应和 NOM 的分散效应。这些结果有望提高我们对纳米粒子在水环境中的胶体行为和归宿的认识。
