The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Photo Marie Skepö

Marie Skepö

Professor

Photo Marie Skepö

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

Author

  • Axel Thuresson
  • Maria Jansson
  • Tomás S. Plivelic
  • Marie Skepö

Summary, in English

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.

Department/s

  • Computational Chemistry
  • MAX IV Laboratory
  • eSSENCE: The e-Science Collaboration

Publishing year

2017-04-13

Language

English

Pages

7951-7958

Publication/Series

Journal of Physical Chemistry C

Volume

121

Issue

14

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Physical Chemistry (including Surface- and Colloid Chemistry)

Status

Published

ISBN/ISSN/Other

  • ISSN: 1932-7447