Activity coefficients of individual ions in LaCl₃from the II+IW theory

Abstract

We investigate the individual activity coefficients of ions in LaCl3 using our theory that is based on the competition of ion-ion (II) and ion-water (IW) interactions (Vincze et al., J. Chem. Phys. 133, 154507, 2010). The II term is computed from Grand Canonical Monte Carlo simulations on the basis of the implicit solvent model of electrolytes using hard sphere ions with Pauling radii. The IW term is computed on the basis of Born's treatment of solvation using experimental hydration free energies.The results show good agreement with experimental data for La 3+ . This agreement is remarkable considering the facts that (i) the result is the balance of two terms that are large in absolute value (up to 20kT ) but opposite in sign , and (ii) that our model does not contain any adjustable parameter.All the parameters used in the model are taken from experiments: concentration dependent dielectric constant, hydration free energies, Pauling radii.

Analysis of Some Electrolyte Models Including Their Ability to Predict the Activity Coefficients of Individual Ions

“…It appears, thus, that both terms (II and IW) are of equal importance in the representation of electrolyte solutions. This conclusion is in agreement with the studies by Boda, Valiskó, Shilov and Lyashchenko [16][17]41 .…”

“…In a series of papers (especially) since 2010 14,[16][17]31 and ion-water) and hope that such approaches can be incorporated in more advanced methods, as they call the e-SAFT approaches in one of their papers. They emphasize physics and there is no parameter estimation in their works based on experimental.…”

“…Alternatively the extended version of the original DH 28 theory and MSA 17 can also be used for the II calculation 15 . The IW term for ion solvation is calculated by the Born equation 27 .…”

“…DH and MSA contain approximations, while GCMC can give exact results. DH and MSA do not consider ion association, while ion association is an output of a Monte Carlo simulation17 .Valiskó & Boda et al still agree with SL on both the use of Born term and the necessity of concentration-dependent relative static permittivity in both terms (ion-ion…”

Scaling Analysis of the Screening Length in Concentrated Electrolytes

“…We focus on NaCl as screening length measurements in the literature for other inorganic salts are scarce. The upturn in excess chemical potential is commonly attributed to excluded-volume interactions [26] or the combined effects of ion-solvent interactions and ion-ion correlations [27][28][29][30][31][32]. Here, we show that the upturn can be related to experimental measurements of the screening length as a function of concentration.…”