Natural Organic Matter (NOM) Imparts Molecular-Weight-Dependent Steric Stabilization or Electrostatic Destabilization to Ferrihydrite Nanoparticles.,Environmental Science & Technology

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Natural Organic Matter (NOM) Imparts Molecular-Weight-Dependent Steric Stabilization or Electrostatic Destabilization to Ferrihydrite Nanoparticles.
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2020-04-06 , DOI: 10.1021/acs.est.0c01189
Zhixiong Li _{1,

2} , Sheyda Shakiba ₂ , Ning Deng ₂ , Jiawei Chen ₁ , Stacey M Louie ₂ , Yandi Hu ₂

Affiliation

Ferrihydrite nanoparticles (Fh NPs) are ubiquitous in natural environments. However, their colloidal stability, and fate and transport behavior are difficult to predict in the presence of heterogeneous natural organic matter (NOM) mixtures. Here, we investigated the adsorption and aggregation behavior of Fh NPs exposed to NOM fractions with different molecular weights (MW). The NOM fraction with MW < 3 kDa destabilized the NPs, resulting in accelerated aggregation even at high C/Fe mass ratios, whereas higher MW NOM fractions imparted better colloidal stability with increasing MW and C/Fe ratio. Despite differences in the functional group composition of the bulk (dissolved) NOM fractions, all NOM fractions produced similar adsorbed layer compositions on the NPs, suggesting minimal contribution of chemical properties to the distinctive aggregation behavior. Rather, the higher adsorbed mass and larger size of the higher MW fractions were key factors in stabilizing the NPs through steric repulsion, whereas the lowest MW fraction had low adsorbed mass and was unable to counter electrostatic patch-charge attraction when the NPs are positively charged. This mechanistic understanding helps us predict the transport and fate of Fh NPs and the associated contaminants in natural environments with varying NOM compositions.

中文翻译：

天然有机物（NOM）会影响分子重量依赖的立体稳定或对亚铁水合物纳米粒子的静电去稳定作用。

水铁矿纳米粒子（Fh NPs）在自然环境中无处不在。但是，在存在异质天然有机物（NOM）混合物的情况下，很难预测它们的胶体稳定性以及命运和运输行为。在这里，我们研究了暴露于具有不同分子量（MW）的NOM馏分的Fh NPs的吸附和聚集行为。MW <3 kDa的NOM馏分使NP不稳定，即使在高C / Fe质量比的情况下，也会加速聚集，而随着MW和C / Fe比的增加，较高的MW NOM馏分具有更好的胶体稳定性。尽管本体（溶解的）NOM馏分的官能团组成有所不同，但所有NOM馏分在NP上均产生相似的吸附层组成，表明化学性质对独特聚集行为的贡献最小。而是，较高的吸附质量和较高的MW馏分的较大尺寸是通过空间排斥来稳定NP的关键因素，而最低的MW馏分具有较低的吸附质量，并且当NP带正电时无法抵消静电补丁电荷的吸引。。这种机制上的理解有助于我们预测NOM组成变化的自然环境中Fh NP的运输和结局。而最低的MW分数具有较低的吸附质量，并且当NPs带正电时无法抵消静电补丁电荷的吸引。这种机制上的理解有助于我们预测NOM组成变化的自然环境中Fh NP的运输和结局。而最低的MW分数具有较低的吸附质量，并且当NPs带正电时无法抵消静电补丁电荷的吸引。这种机制上的理解有助于我们预测NOM组成变化的自然环境中Fh NP的运输和结局。

更新日期：2020-04-06

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