On the modified Poisson–Boltzmann closure for primitive model electrolytes at high concentration

2021 ◽  
Vol 155 (1) ◽  
pp. 014504
Author(s):  
Christopher W. Outhwaite ◽  
Lutful Bari Bhuiyan
2021 ◽  
Vol 24 (2) ◽  
pp. 23801
Author(s):  
L. B. Bhuiyan

Structure and thermodynamics in restricted primitive model electrolytes are examined using three recently developed versions of a linear form of the modified Poisson-Boltzmann equation. Analytical expressions for the osmotic coefficient and the electrical part of the mean activity coefficient are obtained and the results for the osmotic and the mean activity coefficients are compared with that from the more established mean spherical approximation, symmetric Poisson-Boltzmann, modified Poisson-Boltzmann theories, and available Monte Carlo simulation results. The linear theories predict the thermodynamics to a remarkable degree of accuracy relative to the simulations and are consistent with the mean spherical approximation and modified Poisson-Boltzmann results. The predicted structure in the form of the radial distribution functions and the mean electrostatic potential also compare well with the corresponding results from the formal theories. The excess internal energy and the electrical part of the mean activity coefficient are shown to be identical analytically for the mean spherical approximation and the linear modified Poisson-Boltzmann theories.


1994 ◽  
Vol 100 (11) ◽  
pp. 8301-8306 ◽  
Author(s):  
L. B. Bhuiyan ◽  
C. W. Outhwaite ◽  
M. Molero ◽  
E. González‐Tovar

1998 ◽  
Vol 38 (7) ◽  
pp. 99-106 ◽  
Author(s):  
Ching Yuan ◽  
Chung-Hsuang Hung ◽  
Chad T. Jafvert

The association reactions involving counterions, Na+ and Mg2+, and micelles composed of the anionic surfactant, dodecylsulfate (DS−), were investigated in ultrafiltration experiments. To access the data, an innovative model was developed that considered specific counterion binding within a Stern layer, with binding constant dependent upon the electrical potential as derived by the Poisson-Boltzmann equation and with calculation of the cmc as a function of counterion binding (or association). The experimental and model results both show that magnitude of counterion binding is greater for divalent species, Mg2+, than that for the monovalent species, Na2+. However, high concentration of Na+ compete for surface area diminishing the ability of the DS− to bind either divalent species. At experimental conditions from 0 to 100 mM NaCl addition, the binding ratio (BR) varied only from 0.58 to 0.63. The optimum binding constants, KMg and KNa, were determined to be 0.4 and 1.0 L mol−1, respectively, for the model. The experimental data and model calculated results were generally in good agreement.


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