# Fast, Robust Evaluation of the Equation of State of Suspensions of Charge-Stabilized Colloidal Spheres

dataset

posted on 29.08.2017, 00:00 by Yannick Hallez, Martine MeirelesIncreasing
demand is appearing for the fast, robust prediction
of the equation of state of colloidal suspensions, notably with a
view to using it as input data to calculate transport coefficients
in complex flow solvers. This is also of interest in rheological studies,
industrial screening tests of new formulations, and the real-time
interpretation of osmotic compression experiments, for example. For
charge-stabilized spherical particles, the osmotic pressure can be
computed with standard liquid theories. However, this calculation
can sometimes be lengthy and/or unstable under some physicochemical
conditions, a drawback that precludes its use in multiscale flow simulators.
As a simple, fast, and robust replacement, the literature reports
estimations of the osmotic pressure that have been built by adding
the Carnahan–Starling and the cell model pressures (CSCM model).
The first contribution is intended to account for colloid–colloid
contacts, and the second, for electrostatic effects. This approximation
has not yet been thoroughly tested. In this work, the CSCM is evaluated
by comparison with data from experiments on silica particles, Monte
Carlo simulations, and solutions of the accurate Rogers–Young
integral equation scheme with a hard-sphere Yukawa potential obtained
from the extrapolated point-charge renormalization method for a wide
range of volume fractions, surface charge densities, and interaction
ranges. We find that the CSCM is indeed perfectly adequate in the
electrostatically concentrated regime, where it can be used from vanishingly
small to high surface charge because there is error cancellation between
the Carnahan–Starling and cell model contributions at intermediate
charge. The CSCM is thus a nice extension of the cell model to liquid-like
dense suspensions, which should find application in the domains mentioned
above. However, it fails for dilute suspensions with strong electrostatics.
In this case, we show that, and explain why, perturbation methods
and the rescaled mean spherical approximation are good alternatives
in terms of precision, ease of implementation, computational cost,
and robustness.

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input dataMonte Carlo simulationsRobust EvaluationCharge-Stabilized Colloidal Spheresinteraction rangescompression experimentscell model contributionsliterature reports estimationspoint-charge renormalization methodsilica particlesapproximationscreening testsCarnahanvolume fractionstransport coefficientsCSCM modelsurface chargecell model pressurescell modelsuspensionrheological studiesequationerror cancellationhard-sphere Yukawaphysicochemical conditionsflow solversmultiscale flow simulatorsperturbation methodssurface charge densities