Activities in Aqueous Solutions of the Alkali Halide Salts from Molecular Simulation

Kohns, Maximilian; Schappals, Michael; Horsch, Martin; Hasse, Hans

doi:10.1021/acs.jced.6b00544

Cited by 23 publications

(21 citation statements)

References 44 publications

(99 reference statements)

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“…For a more comprehensive discussion of common parametrization strategies employed for molecular modeling of aqueous electrolyte solutions, see the review of Nezbeda et al 45 In general, however, these strategies yield unsatisfactory predictions for solution properties, such as density, 46 water self-diffusion coefficient, 47 or salt activity. 48,49 In fact, the underprediction of the solubility limit of alkali halide salts, 45,[50][51][52][53][54] resulting in excessive ion pairing [55][56][57] and/or premature crystallization, [58][59][60] is a wellknown problem of non-polarizable ion force fields. The cause may lie in unbalanced force field parameters.…”

Section: Introductionmentioning

confidence: 99%

Dielectric constant and density of aqueous alkali halide solutions by molecular dynamics: A force field assessment

Šarić

Kohns

Vrabec

2020

The Journal of Chemical Physics

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The concentration dependence of the dielectric constant and the density of 11 aqueous alkali halide solutions (LiCl, NaCl, KCl, RbCl, CsCl, LiI, NaI, KI, CsI, KF, and CsF) is investigated by molecular simulation. Predictions using eight non-polarizable ion force fields combined with the TIP4P/ε water model are compared to experimental data. The influence of the water model and the temperature on the results for the NaCl brine are also addressed. The TIP4P/ε water model improves the accuracy of dielectric constant predictions compared to the SPC/E water model. The solution density is predicted well by most ion models. Almost all ion force fields qualitatively capture the decline of the dielectric constant with the increase of concentration for all solutions and with the increase of temperature for NaCl brine. However, the sampled dielectric constant is mostly in poor quantitative agreement with experimental data. These results are related to the microscopic solution structure, ion pairing, and ultimately the force field parameters. Ion force fields with excessive contact ion pairing and precipitation below the experimental solubility limit generally yield higher dielectric constant values. An adequate reproduction of the experimental solubility limit should therefore be a prerequisite for further investigations of the dielectric constant of aqueous electrolyte solutions by molecular simulation.

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Section: Introductionmentioning

confidence: 99%

Dielectric constant and density of aqueous alkali halide solutions by molecular dynamics: A force field assessment

Šarić

Kohns

Vrabec

2020

The Journal of Chemical Physics

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“…Several studies have shown that the degree of water weakening is also affected by the salinity of the pore fluid [12,18,38]. The salinity of the solution affects both the EDL component of the DLVO forces, and the water activity [39,40]. It also changes the calcite dissolution kinetics in aqueous solutions [41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

“…This then affects surface water absorption on both hydrophilic surfaces, and results in less required force to make adhesive contacts due to the decrease in both magnitude and onset of the hydration forces [50]. Risnes et al [12] and Rostom et al [38] also showed that the strength of car-345 bonate rocks and the fracture threshold of calcite are affected by the salinity level of pore fluid and attributed this to the level of water activity in the solution [39,76,77]. However, in our system the difference between water activity at highest and lowest values is trivial (0.95 ≤ a w ≤ 1, calculated by PHREEQC).…”

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Adhesive forces between two cleaved calcite surfaces in NaCl solutions: The importance of ionic strength and normal loading

Javadi

Røyne

2018

Journal of Colloid and Interface Science

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The mechanical strength of calcite bearing rocks is influenced by pore fluid chemistry due to the variation in nano-scale surface forces acting at the grain contacts or close to the fracture tips. The adhesion of two contacting surfaces, which affects the macroscopic strength of the material, is not only influenced by the fluid chemistry but also by the surface topography. In this paper, we use Atomic Force Microscope (AFM) to measure the interfacial forces between two freshly cleaved calcite surfaces in CaCO-saturated solutions with varying NaCl concentration. We show that calcite contacts become stronger with increasing NaCl concentration (>100 mM), as a result of progressively weaker secondary hydration and increasing attraction due to instantaneous ion-ion correlation. Moreover, we discuss the effect of normal applied force (F) and surface roughness on the measured adhesion forces (F). We show that the measured pull-off force (adhesion) is linearly correlated with the magnitude of F, where an increase in applied force results in increased adhesion. This is attributed to a larger number of contacting surface asperities and thus increase in real contact area and the contact-bond strength. We discuss that the possible variation in local topography at contacts, together with strong dependence on ionic strength of the solution, can explain the inconsistent behavior of calcite rocks in NaCl solutions.

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“…However, the systematic assessment of Orozco et al [24] shows that none of the existing model parameterizations is able to quantitatively describe several properties at once. This suggests that better model parameterizations can be found [25]. For a more detailed discussion of the recent advances in the field, see the comprehensive review by Nezbeda et al [26].…”

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confidence: 99%

Partial molar volume of NaCl and CsCl in mixtures of water and methanol by experiment and molecular simulation

Kohns

Horsch

Hasse

2018

Fluid Phase Equilibria

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Densities of solutions of NaCl and CsCl in mixtures of water and methanol are determined by experiment and molecular dynamics simulation. Both experiments and simulations cover the concentration range up to the solubility limit of the salt in the temperature range 288.15 ≤ T / K ≤ 318.15 at ambient pressure. Non-polarizable molecular models from the literature are used for the ions and solvents. The partial molar volume of the salts at infinite dilution in the mixed solvent is determined from an empirical correlation of the data. The mixed solvent effects on the density and the partial molar volumes of the salts are well predicted by the molecular models.

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Activities in Aqueous Solutions of the Alkali Halide Salts from Molecular Simulation

Cited by 23 publications

References 44 publications

Dielectric constant and density of aqueous alkali halide solutions by molecular dynamics: A force field assessment

Dielectric constant and density of aqueous alkali halide solutions by molecular dynamics: A force field assessment

Adhesive forces between two cleaved calcite surfaces in NaCl solutions: The importance of ionic strength and normal loading

Partial molar volume of NaCl and CsCl in mixtures of water and methanol by experiment and molecular simulation

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