Donnan potential of dilute colloidal dispersions: Monte Carlo simulations

Tzu Yu Wang, Yu Jane Sheng, Heng Kwong Tsao

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Donnan equilibrium between a salt-free colloidal dispersion and an electrolyte solution has been investigated by Monte Carlo simulations. The Donnan potential is directly calculated by considering two compartments separated by a semipermeable membrane. In order to understand the role played by colloid-ion interactions, the influences of colloidal characteristics, including particle size R, intrinsic particle charge Z, counterion valency zc, and concentration cp, on Donnan potential ΨD and effective charge Zeff are examined. Our simulations show that the electroneutrality condition is not followed in both compartments and the Donnan potential arises due to the net charge density. The Donnan potential grows by increasing cp and Zeff and by decreasing dielectric constant εr, i.e., ΨD ∼ Zeff cp / εr approximately. Note that the effective charge varies with R, Z, cp, εr and zc as well. When the salt concentration is increased, the net charge density is lowered and thus the Donnan potential decays accordingly. The validity of the classical theory based on the Nernst equation and the electroneutrality assumption is also examined. In general, the simulation results at high-salt condition can be well represented by such mean-field theory.

Original languageEnglish
Pages (from-to)192-201
Number of pages10
JournalJournal of Colloid and Interface Science
Volume340
Issue number2
DOIs
StatePublished - 15 Dec 2009

Keywords

  • Colloidal phenomena
  • Complex fluids
  • Donnan potential
  • Effective charge
  • Simulation
  • Suspension

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