Chemical Potentials of Hard-Core Molecules by a Stepwise Insertion Method

Maciel, Jéssica C. da S. L.; Abreu, Charlles R. A.; Tavares, Frederico W.

doi:10.1590/0104-6632.20180352s20160276

Cited by 5 publications

(2 citation statements)

References 31 publications

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“…The pH in the reservoir is determined by pH gc = −log 10 [ a H + / c ⊖ ], with the activity of hydronium ions in the reservoir a H + = c H + exp(βμ ex ), where μ ex = μ CS + μ MSA is the excess chemical potential. The nonideality effects due to Coulomb interactions are taken into account at the mean spherical approximation (MSA) level, while the hard core contribution is calculated using the Carnahan–Starling equation of state − β μ MSA = λ B ( 1 + 2 κ d − κ d − 1 ) d 2 κ , .25em β μ CS = 8 η − 9 η 2 + 3 η 3 ( 1 − η ) 3 where η = π d 3 3 c t , c t = c s + c a is the total concentration of salt and acid, λ B = q 2 /ϵ w k B T = 7.2 Å is the Bjerrum length, and κ = 8 π λ B c t is the inverse Debye length. The surface groups are characterized by p K a = −log 10 [ K a / c ⊖ ], where K a is the acid dissociation constant of surface groups and φ 0 is the mean-field electrostatic potential at the surface titration sites.…”

Section: Theorymentioning

confidence: 99%

Titration in Canonical and Grand-Canonical Ensembles

Bakhshandeh,

Levin

2023

J. Phys. Chem. B

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We discuss problems associated with the notion of pH in heterogeneous systems. For homogeneous systems, standardization protocols lead to a well-defined quantity, which, although different from Sørensen's original idea of pH, is well reproducible and has become accepted as the measure of the "hydrogen potential". On the other hand, for heterogeneous systems, pH defined in terms of the chemical part of the electrochemical activity is thermodynamically inconsistent and runs afoul of the Gibbs−Guggenheim principle that forbids splitting of the electrochemical potential into separate chemical and electrostatic parts, since only the sum of two has any thermodynamic meaning. The problem is particularly relevant for modern simulation methods which involve charge regulation of proteins, polyelectrolytes, nanoparticles, colloidal suspensions, and so forth. In this paper, we show that titration isotherms calculated using semigrand canonical simulations can be very different from the ones obtained using canonical reactive Monte Carlo simulations.

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Section: Theorymentioning

confidence: 99%

Titration in Canonical and Grand-Canonical Ensembles

Bakhshandeh,

Levin

2023

J. Phys. Chem. B

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“…, [66][67][68][69] where the volume fraction is η = πd 3 3 c t . The total excess chemical potential of an ion is then µ ex = µ CS + µ M SA .…”

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confidence: 99%

Reactive Monte Carlo Simulations for Charge Regulation of Colloidal Particles

Bakhshandeh,

Frydel,

Levin

2021

Preprint

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We present a reactive Monte Carlo simulation method to study acid-base equilibrium that controls charge regulation in colloidal systems. The simulations use a semi-grand canonical ensemble in which colloidal suspension is in contact with a reservoir of salt and strong acid. The surface reactions are controlled by the equilibrium constants, which correspond to either the internal partition function of a protonated acid surface group or a group with a specifically adsorbed cation. The interior of colloidal particles is modeled as a low dielectric medium, different from the surrounding water. The effective colloidal charge is calculated for different number of surface acidic groups, pH, salt concentrations, and types of electrolyte. The results are compared with the experimental measurements of the effective colloidal charge obtained using potentiometric titration. Excellent agreement is found between simulations and experiments.The interplay between electrostatic interactions 1-21 and acid-base equilibrium is of paramount importance in Chemistry and Biology. [22][23][24][25][26][27] It often defines the boundary between life and

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Reactive Monte Carlo simulations for charge regulation of colloidal particles

Bakhshandeh

Frydel

Levin

2022

The Journal of Chemical Physics

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We use a reactive Monte Carlo simulation method and the primitive model of electrolyte to study acid–base equilibrium that controls charge regulation in colloidal systems. The simulations are performed in a semi-grand canonical ensemble in which colloidal suspension is in contact with a reservoir of salt and strong acid. The interior of colloidal particles is modeled as a low dielectric medium, different from the surrounding water. The effective colloidal charge is calculated for different numbers of surface acidic groups, pH, salt concentrations, and types of electrolyte. In the case of potassium chloride, the titration curves are compared with the experimental measurements obtained using potentiometric titration. A good agreement is found between simulations and experiments. In the case of lithium chloride, the specific ionic adsorption is taken into account through the partial dehydration of lithium ion.

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Chemical Potentials of Hard-Core Molecules by a Stepwise Insertion Method

Cited by 5 publications

References 31 publications

Titration in Canonical and Grand-Canonical Ensembles

Titration in Canonical and Grand-Canonical Ensembles

Reactive Monte Carlo Simulations for Charge Regulation of Colloidal Particles

Reactive Monte Carlo simulations for charge regulation of colloidal particles

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