Ferrihydrite Nanoparticle Aggregation Induced by Dissolved Organic Matter,The Journal of Physical Chemistry A

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Ferrihydrite Nanoparticle Aggregation Induced by Dissolved Organic Matter
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2018-08-30 00:00:00 , DOI: 10.1021/acs.jpca.8b05622
Luigi Gentile ₁ , Tao Wang ₁ , Anders Tunlid ₁ , Ulf Olsson ₂ , Per Persson _{1,

3}

Affiliation

Ferrihydrite (Fh) nanoparticles are omnipresent in nature and often highly mobile because of their colloidal stability. Thus, Fh serves as a vector for iron as well as associated nutrients and contaminants. Here, we demonstrate, using small-angle X-ray scattering combined with cryo-transmission electron microscopy (cryo-TEM), that dissolved organic matter (DOM), extracted from a boreal forest soil, induce aggregation of Fh nanoparticles, of radius 3 nm, into fractal aggregates, having a fractal dimension D = 1.7. The DOM consists of both fractal-like colloids (>100 nm) and small molecular DOM, but the attractive Fh interparticle interaction was mediated by molecular DOM alone as shown by cryo-TEM. This highlights the importance of using soil extracts, including all size fractions, in studies of the colloidal behavior of DOM–mineral aggregates. The Fh nanoparticles also self-assemble during synthesis into aggregates with the same fractal dimension as the DOM–Fh aggregates. We propose that, in both the absence and presence of DOM, the aggregation is controlled by the Fh particle charge, and the process can be viewed as a linear polymerization into a self-avoiding random walk structure. The theoretical D value for this is ⁵/₃, which is in close agreement with our Fh and DOM–Fh results.

中文翻译：

溶解有机物诱导的水铁矿纳米粒子聚集

水铁矿（Fh）纳米粒子在自然界中无处不在，并且由于其胶体稳定性而经常具有很高的移动性。因此，Fh可作为铁以及相关养分和污染物的载体。在这里，我们证明，使用小角度X射线散射结合低温透射电子显微镜（cryo-TEM），从北方森林土壤中提取的溶解有机物（DOM）诱导了半径3的Fh纳米粒子的聚集纳米，到分形聚集体中，其分形维数为D= 1.7。DOM由分形胶体（> 100 nm）和小分子DOM组成，但Fh粒子间的相互作用很吸引人，仅通过分子DOM即可介导，如cryo-TEM所示。这突出了在研究DOM-矿物聚集体的胶体行为时，使用土壤提取物（包括所有大小的级分）的重要性。Fh纳米颗粒在合成过程中也自组装成与DOM–Fh聚集体相同的分形维数的聚集体。我们提出，在不存在和存在DOM的情况下，聚集都受Fh粒子电荷的控制，并且该过程可以看作是线性聚合成自规避的随机游走结构。理论d为这个值是⁵ / ₃，这与我们的Fh和DOM–Fh结果非常一致。

更新日期：2018-08-30

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