Aggregation and Dissolution of 4 nm ZnO Nanoparticles in Aqueous Environments: Influence of pH, Ionic Strength, Size, and Adsorption of Humic Acid
Aggregation and Dissolution of 4 nm ZnO Nanoparticles in Aqueous Environments: Influence of pH, Ionic Strength, Size, and Adsorption of Humic Acid
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DOI：
10.1021/la200570n
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发表时间：
2011-05-17
期刊：
影响因子：
3.9
通讯作者：
Grassian, Vicki H.
中科院分区：
文献类型：
--
作者：
Bian, Shao-Wei;Mudunkotuwa, Imali A.;Grassian, Vicki H.
金属氧化物纳米颗粒被用于广泛的商业产品中，导致人们对这些材料在水生环境中的行为越来越感兴趣。目前的研究集中在一些最小的ZnO纳米材料，4 +/- 1纳米直径的纳米粒子，在水溶液中的pH值和离子强度的函数，以及对腐殖酸的吸附的稳定性。由于有吸引力的粒子-粒子相互作用的纳米粒子聚集的测量表明，离子强度，pH值，和腐殖酸的吸附影响ZnO纳米粒子在水溶液中的聚集，这是从Derjaguin-Landau-Verwey-Overbeek（DLVO）理论预期的趋势一致。在低pH和高pH下的纳米颗粒溶解的测量结果表明，锌离子可以被释放到水相中，并且在某些条件下，但不是所有条件下，腐殖酸可以增加Zn 2+（aq）浓度。不同纳米颗粒直径的ZnO纳米颗粒（包括接近1 S和240 nm的纳米颗粒）的溶解的比较表明，最小的纳米颗粒更容易溶解。虽然定性的这种增强溶解可以预测的经典热力学，定量的溶解行为并不能很好地描述。
Metal oxide nanoparticles are used in a wide range of commercial products, leading to an increased interest in the behavior of these materials in the aquatic environment. The current study focuses on the stability of some of the smallest ZnO nanomaterials, 4 +/- 1 nm in diameter nanoparticles, in aqueous solutions as a function of pH and ionic strength as well as upon the adsorption of humic acid. Measurements of nanoparticle aggregation due to attractive particle-particle interactions show that ionic strength, pH, and adsorption of humic acid affect the aggregation of ZnO nanoparticles in aqueous solutions, which are consistent with the trends expected from Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Measurements of nanoparticle dissolution at both low and high pH show that zinc ions can be released into the aqueous phase and that humic acid under certain, but not all, conditions can increase Zn2+(aq) concentrations. Comparison of the dissolution of ZnO nanoparticles of different nanoparticle diameters, including those near IS and 240 nm, shows that the smallest nanoparticles dissolve more readily. Although qualitatively this enhancement in dissolution can be predicted by classical thermodynamics, quantitatively it does not describe the dissolution behavior very well.