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Ferrihydrite Nanoparticle Aggregation Induced by Dissolved Organic Matter

Gentile, Luigi LU ; Wang, Tao LU ; Tunlid, Anders LU ; Olsson, Ulf LU and Persson, Per LU (2018) In Journal of Physical Chemistry A 122(38). p.7730-7738
Abstract

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... (More)

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.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry A
volume
122
issue
38
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85053498897
ISSN
1089-5639
DOI
10.1021/acs.jpca.8b05622
language
English
LU publication?
yes
id
7967dde7-2ca6-4a1e-974e-a0b43a5ec14b
date added to LUP
2018-10-22 13:43:49
date last changed
2019-05-17 12:06:07
@article{7967dde7-2ca6-4a1e-974e-a0b43a5ec14b,
  abstract     = {<p>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 (&gt;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 <sup>5</sup>/<sub>3</sub>, which is in close agreement with our Fh and DOM-Fh results.</p>},
  author       = {Gentile, Luigi and Wang, Tao and Tunlid, Anders and Olsson, Ulf and Persson, Per},
  issn         = {1089-5639},
  language     = {eng},
  number       = {38},
  pages        = {7730--7738},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry A},
  title        = {Ferrihydrite Nanoparticle Aggregation Induced by Dissolved Organic Matter},
  url          = {http://dx.doi.org/10.1021/acs.jpca.8b05622},
  volume       = {122},
  year         = {2018},
}