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The specific co-ion effect on gelling and surface charging of silica nanoparticles : Speculation or reality?

Simonsson, Isabelle ; Sögaard, Christian ; Rambaran, Mark LU and Abbas, Zareen (2018) In Colloids and Surfaces A: Physicochemical and Engineering Aspects 559. p.334-341
Abstract

Based on extensive experimental investigations on many different oxide nanoparticles, it is now a well-established view that the counter-ions exhibit ion specific effects due to their high charge density and strong interaction with oppositively charged surfaces. On the other hand, studies regarding co-ion effects are scarcely reported in the literature. In this study we have measured the surface charge densities and gel-times of silica nanoparticles in a number of salts which have the same counter-ions but different co-ions, i.e. anions in this case. Gel-times were measured in LiCl, NaCl, NaNO3, NaClO4, NaClO3 and Na2SO4 as well as in KCl, KNO3, and... (More)

Based on extensive experimental investigations on many different oxide nanoparticles, it is now a well-established view that the counter-ions exhibit ion specific effects due to their high charge density and strong interaction with oppositively charged surfaces. On the other hand, studies regarding co-ion effects are scarcely reported in the literature. In this study we have measured the surface charge densities and gel-times of silica nanoparticles in a number of salts which have the same counter-ions but different co-ions, i.e. anions in this case. Gel-times were measured in LiCl, NaCl, NaNO3, NaClO4, NaClO3 and Na2SO4 as well as in KCl, KNO3, and K2SO4. We have seen clear correlations between the gel-times and the extent of ion pairing in the solutions; salts that have strong ion pairing exhibit longer gel-times than salts having highly dissociated ions. To better understand the mechanisms at work we have determined the surface charging of silica nanoparticles in these salt solutions and we have observed that the surface charging behavior of silica nanoparticles follows the trends seen in the gel-time studies. From our gel-time determinations and potentiometric measurements we can claim that there is a clear co-ion effect on the gelling and surface charging of silica nanoparticles.

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author
; ; and
publishing date
type
Contribution to journal
publication status
published
keywords
Activity coefficients, Co-ion effect, Gel-Times, Ion pairing, Potentiometric titrations, Silica nanoparticles, Silica surface chemistry, Surface charge
in
Colloids and Surfaces A: Physicochemical and Engineering Aspects
volume
559
pages
8 pages
publisher
Elsevier
external identifiers
  • scopus:85054284477
ISSN
0927-7757
DOI
10.1016/j.colsurfa.2018.09.057
language
English
LU publication?
no
additional info
Publisher Copyright: © 2018 Elsevier B.V.
id
4986d4a4-7d7b-42b1-8d9b-4aba3013b4f1
date added to LUP
2023-02-15 16:55:08
date last changed
2023-03-06 13:10:58
@article{4986d4a4-7d7b-42b1-8d9b-4aba3013b4f1,
  abstract     = {{<p>Based on extensive experimental investigations on many different oxide nanoparticles, it is now a well-established view that the counter-ions exhibit ion specific effects due to their high charge density and strong interaction with oppositively charged surfaces. On the other hand, studies regarding co-ion effects are scarcely reported in the literature. In this study we have measured the surface charge densities and gel-times of silica nanoparticles in a number of salts which have the same counter-ions but different co-ions, i.e. anions in this case. Gel-times were measured in LiCl, NaCl, NaNO<sub>3</sub>, NaClO<sub>4</sub>, NaClO<sub>3</sub> and Na<sub>2</sub>SO<sub>4</sub> as well as in KCl, KNO<sub>3</sub>, and K<sub>2</sub>SO<sub>4</sub>. We have seen clear correlations between the gel-times and the extent of ion pairing in the solutions; salts that have strong ion pairing exhibit longer gel-times than salts having highly dissociated ions. To better understand the mechanisms at work we have determined the surface charging of silica nanoparticles in these salt solutions and we have observed that the surface charging behavior of silica nanoparticles follows the trends seen in the gel-time studies. From our gel-time determinations and potentiometric measurements we can claim that there is a clear co-ion effect on the gelling and surface charging of silica nanoparticles.</p>}},
  author       = {{Simonsson, Isabelle and Sögaard, Christian and Rambaran, Mark and Abbas, Zareen}},
  issn         = {{0927-7757}},
  keywords     = {{Activity coefficients; Co-ion effect; Gel-Times; Ion pairing; Potentiometric titrations; Silica nanoparticles; Silica surface chemistry; Surface charge}},
  language     = {{eng}},
  month        = {{12}},
  pages        = {{334--341}},
  publisher    = {{Elsevier}},
  series       = {{Colloids and Surfaces A: Physicochemical and Engineering Aspects}},
  title        = {{The specific co-ion effect on gelling and surface charging of silica nanoparticles : Speculation or reality?}},
  url          = {{http://dx.doi.org/10.1016/j.colsurfa.2018.09.057}},
  doi          = {{10.1016/j.colsurfa.2018.09.057}},
  volume       = {{559}},
  year         = {{2018}},
}