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Temperature Response of Charged Colloidal Particles by Mixing Counterions Utilizing Ca2+/Na+ Montmorillonite as Model System

Thuresson, Axel LU ; Jansson, Maria LU ; Plivelic, Tomás S. LU and Skepö, Marie LU (2017) In Journal of Physical Chemistry C 121(14). p.7951-7958
Abstract

The osmotic pressure and the aggregation of charged colloids as a function of temperature have been investigated using Monte Carlo and molecular dynamics simulations for different ratios of monovalent and divalent counterions. In the simulations the water is treated as a temperature-dependent dielectric continuum, and only the electrostatic interactions are considered. It was found that the temperature response can be controlled, i.e., the osmotic pressure can increase, decrease, or be kept constant, as a function of temperature depending on the monovalent/divalent counterion ratio. The increase in osmotic pressure with temperature, which occurs at low enough surface charge density and/or low fraction of divalent ions, can be understood... (More)

The osmotic pressure and the aggregation of charged colloids as a function of temperature have been investigated using Monte Carlo and molecular dynamics simulations for different ratios of monovalent and divalent counterions. In the simulations the water is treated as a temperature-dependent dielectric continuum, and only the electrostatic interactions are considered. It was found that the temperature response can be controlled, i.e., the osmotic pressure can increase, decrease, or be kept constant, as a function of temperature depending on the monovalent/divalent counterion ratio. The increase in osmotic pressure with temperature, which occurs at low enough surface charge density and/or low fraction of divalent ions, can be understood from the DLVO theory. The origin of the opposite behavior can be explained by the enhanced attractive electrostatic ion-ion correlation interactions with temperature. The constraint is that the absolute value of the surface charge density of the colloids must be above a certain threshold, i.e., high enough such that the attractive ion-ion correlations can dominate the interaction regarding the divalent ions. The current conclusions are supported by the microstructural characterization of Ca2+/Na+-montmorillonite clay using small-angle X-ray scattering. A qualitative agreement is observed between the simulations and the experimental data.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry C
volume
121
issue
14
pages
8 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85019996566
  • wos:000399629000040
ISSN
1932-7447
DOI
10.1021/acs.jpcc.7b00882
language
English
LU publication?
yes
id
990102e6-c05d-4bf0-b346-26cf557de026
date added to LUP
2017-06-28 15:56:42
date last changed
2017-09-18 11:43:38
@article{990102e6-c05d-4bf0-b346-26cf557de026,
  abstract     = {<p>The osmotic pressure and the aggregation of charged colloids as a function of temperature have been investigated using Monte Carlo and molecular dynamics simulations for different ratios of monovalent and divalent counterions. In the simulations the water is treated as a temperature-dependent dielectric continuum, and only the electrostatic interactions are considered. It was found that the temperature response can be controlled, i.e., the osmotic pressure can increase, decrease, or be kept constant, as a function of temperature depending on the monovalent/divalent counterion ratio. The increase in osmotic pressure with temperature, which occurs at low enough surface charge density and/or low fraction of divalent ions, can be understood from the DLVO theory. The origin of the opposite behavior can be explained by the enhanced attractive electrostatic ion-ion correlation interactions with temperature. The constraint is that the absolute value of the surface charge density of the colloids must be above a certain threshold, i.e., high enough such that the attractive ion-ion correlations can dominate the interaction regarding the divalent ions. The current conclusions are supported by the microstructural characterization of Ca<sup>2+</sup>/Na<sup>+</sup>-montmorillonite clay using small-angle X-ray scattering. A qualitative agreement is observed between the simulations and the experimental data.</p>},
  author       = {Thuresson, Axel and Jansson, Maria and Plivelic, Tomás S. and Skepö, Marie},
  issn         = {1932-7447},
  language     = {eng},
  month        = {04},
  number       = {14},
  pages        = {7951--7958},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry C},
  title        = {Temperature Response of Charged Colloidal Particles by Mixing Counterions Utilizing Ca<sup>2+</sup>/Na<sup>+</sup> Montmorillonite as Model System},
  url          = {http://dx.doi.org/10.1021/acs.jpcc.7b00882},
  volume       = {121},
  year         = {2017},
}