On the equation of state of charged colloidal systems

Groot, Robert D.
April 1991
Journal of Chemical Physics;4/1/1991, Vol. 94 Issue 7, p5083
Academic Journal
The mean spherical approximation (MSA) is applied to the ‘‘primitive model’’ of electrolytes to calculate the osmotic pressure of a charged colloidal system. For a two-component system of large particles (1 μm diameter) and counterions, the MSA predicts a correction to the ideal gas law which is proportional to ρ3/4. This result should be compared to the Debye–Hückel correction, which is proportional to ρ3/2. As a result of this power (3)/(4) the MSA equation of state describes phase separation in combination with a very low spinodal density. To study the importance of the nonlinear effects, a correction based on the Poisson–Boltzmann equation is proposed. The resulting equation of state qualitatively shows the same behavior as the MSA does, however, the correction to the ideal gas law is reduced by a factor of four. In the three-component system (colloid particles, counterions, and coions) the parameter range where phase separation occurs is limited to not only low dielectric permittivity, but also to low salt concentrations.


Related Articles

  • Solid–liquid transition of charge-stabilized colloidal dispersions: a single-component structure-function approach. Zhou, Shiqi // Canadian Journal of Physics;May2004, Vol. 82 Issue 5, p357 

    We have extended the Raveché–Mountain–Streett one-phasecriterion that governs the freezing of Lennard-Jones systems to a hard-core repulsive Yukawa-model (HCRYM) system. We find in the framework of the Rogers–Young (RY) approximation for an Ornstein–Zernike...

  • Analysis of osmotic pressure data for aqueous protein solutions via a multicomponent model. Druchok, M.; Kalyuzhnyi, Yu.; Resˇcˇicˇ, J.; Vlachy, V. // Journal of Chemical Physics;3/21/2006, Vol. 124 Issue 11, p114902 

    Integral equation theories and Monte Carlo simulations were used to study the Donnan equilibrium, which is established by an equilibrium distribution of a simple electrolyte between an aqueous protein-electrolyte mixture and an aqueous solution of the same simple electrolyte, when these two...

  • Crystallization of Colloidal Plasma: Model of Charge Renormalization with Addition of Salt. Allahyarov, E.; Trigger, S. // High Temperature;May2005, Vol. 43 Issue 3, p315 

    A new procedure is suggested for macroion charge renormalization, which describes the melting curve of charged colloidal liquids as a function of concentration of added salt. The method is based on the gel model approximation with new boundary conditions for the minor-ion charge density...

  • Haloing, flocculation, and bridging in colloid-nanoparticle suspensions. Scheer, Everett N.; Schweizer, Kenneth S. // Journal of Chemical Physics;4/28/2008, Vol. 128 Issue 16, p164905 

    Integral equation theory with a hybrid closure approximation is employed to study the equilibrium structure of highly size asymmetric mixtures of spherical colloids and nanoparticles. Nonequilibrium contact aggregation and bridging gel formation is also qualitatively discussed. The effect of...

  • Effect of the Donnan osmotic pressure on the volume phase transition of hydrated gels. Sasaki, Shigeo; Maeda, Hiroshi // Journal of Chemical Physics;7/15/1997, Vol. 107 Issue 3, p1028 

    Explains the influence of the Donnan osmotic pressure on the volume phase transition of hydrated polymer colloids. Parameter values; Chain segments in two states; Free energy rates; Assumption of interaction energies.

  • On the WKBJ approximation. El Sawi, M. // Journal of Mathematical Physics;Mar1987, Vol. 28 Issue 3, p556 

    A simple approach employing properties of solutions of differential equations is adopted to derive an appropriate extension of the WKBJ method. Some of the earlier techniques that are commonly in use are unified, whereby the general approximate solution to a second-order homogeneous linear...

  • Detailed behavior of the phase-integral approximations at zeros and singularities of the square of the base function. Skorupski, Andrzej A. // Journal of Mathematical Physics;Aug88, Vol. 29 Issue 8, p1814 

    Approximate solutions to the one-dimensional time independent wave equation, called the phase-integral approximations, are analyzed in the vicinity of characteristic points. The approximations are of arbitrary order and are generated from an unspecified base function. The general theory is...

  • Exact solutions of coupled-wave equations in piezoelectric solids. Ren, Wei // Journal of Mathematical Physics;Nov93, Vol. 34 Issue 11, p5376 

    The homogeneous coupled-wave equations under the quasistatic approximation are exactly solved by using the method of angular-spectrum expansions. And Weyl’s method of deriving the scalar Green’s functions in an isotropic media is generalized to the study of the tensor...

  • A highly connected random master equation. Zwanzig, Robert // Journal of Chemical Physics;12/1/1995, Vol. 103 Issue 21, p9397 

    In a highly connected master equation, each state is connected to a substantial fraction of all other states. A special case, in which the connections are made at random, is investigated here by means of an effective medium approximation. The eigenvalue spectrum of the resulting effective medium...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics