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Anomalous temperature behavior in clay swelling due to ion-ion correlations

Thuresson, A. LU ; Karnland, O. LU and Jönsson, B. LU (2016) In Europhysics Letters 114(3).
Abstract

We show, experimentally and theoretically, that swelling of both natural and refined clays has an anomalous temperature behavior depending on counterion valency. In an aqueous clay dispersion dominated by monovalent counterions the swelling pressure increases with temperature as expected from entropic arguments. In a clay with predominantly divalent counterions, the opposite behavior is found. The explanation is due to the fact that ion-ion correlations increase with temperature. Ion-ion correlations are important at strong electrostatic coupling and in an aqueous solution the dielectric permittivity, ϵr, drops with increased temperature, T, in such a way that the product ϵrT also decreases. Thus, the net effect is... (More)

We show, experimentally and theoretically, that swelling of both natural and refined clays has an anomalous temperature behavior depending on counterion valency. In an aqueous clay dispersion dominated by monovalent counterions the swelling pressure increases with temperature as expected from entropic arguments. In a clay with predominantly divalent counterions, the opposite behavior is found. The explanation is due to the fact that ion-ion correlations increase with temperature. Ion-ion correlations are important at strong electrostatic coupling and in an aqueous solution the dielectric permittivity, ϵr, drops with increased temperature, T, in such a way that the product ϵrT also decreases. Thus, the net effect is an increased coupling.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Europhysics Letters
volume
114
issue
3
publisher
EDP Sciences
external identifiers
  • scopus:84975882006
ISSN
0295-5075
DOI
10.1209/0295-5075/114/38002
language
English
LU publication?
yes
id
3176dee6-b152-4b04-a253-0faaa41bb261
date added to LUP
2016-07-26 09:39:24
date last changed
2017-02-02 12:55:35
@article{3176dee6-b152-4b04-a253-0faaa41bb261,
  abstract     = {<p>We show, experimentally and theoretically, that swelling of both natural and refined clays has an anomalous temperature behavior depending on counterion valency. In an aqueous clay dispersion dominated by monovalent counterions the swelling pressure increases with temperature as expected from entropic arguments. In a clay with predominantly divalent counterions, the opposite behavior is found. The explanation is due to the fact that ion-ion correlations increase with temperature. Ion-ion correlations are important at strong electrostatic coupling and in an aqueous solution the dielectric permittivity, ϵ<sub>r</sub>, drops with increased temperature, T, in such a way that the product ϵ<sub>r</sub>T also decreases. Thus, the net effect is an increased coupling.</p>},
  articleno    = {38002},
  author       = {Thuresson, A. and Karnland, O. and Jönsson, B.},
  issn         = {0295-5075},
  language     = {eng},
  month        = {05},
  number       = {3},
  publisher    = {EDP Sciences},
  series       = {Europhysics Letters},
  title        = {Anomalous temperature behavior in clay swelling due to ion-ion correlations},
  url          = {http://dx.doi.org/10.1209/0295-5075/114/38002},
  volume       = {114},
  year         = {2016},
}