Surface and interfacial tensions of Hofmeister electrolytes

Abstract

We present a theory that is able to account quantitatively for the surface and interfacial tensions of different electrolyte solutions. It is found that near the interface, ions can be separated into two classes: the kosmotropes and the chaotropes. While the kosmotropes remain hydrated near the interface and are repelled from it, the chaotropes loose their hydration sheath and become adsorbed to the surface. The anionic adsorption is strongly correlated with the Jones-Dole viscosity B-coefficient. Both hydration and polarizability must be taken into account to obtain a quantitative agreement with the experiments. To calculate the excess interfacial tension of the oil-electrolyte interface, the dispersion interactions must also be included. The theory can also be used to calculate the surface and the interfacial tensions of acid solutions, predicting a strong surface adsorption of hydronium ion.

Applying electric field to charged and polar particles between metallic plates: Extension of the Ewald method

“…(4) Various systems such as charged colloids, polyelectrolytes, proteins, and water molecules should exhibit interesting behaviors close to metal surfaces without and with applied field [22][23][24] . For polarizable surfaces, a simulation method similar to ours has recently been reported 41 . (5) We may well expect ferroelectric phase transitions in confined dipole systems (see the sentences below Eq.…”

Small molecule solvation changes due to the presence of salt are governed by the cost of solvent cavity formation and dispersion

“…It is hard to separate the cavity and water structure concepts for changes in the nonpolar solvation term because surface tension changes are largely correlated with ion-induced water structure changes. 55 Countering this, we observe negative polar solvation differences for all but the purely nonpolar solutes investigated. These negative G pol may result from stronger electrostatic interactions of polar solutes with the charges present in an electrolyte solution than that seen in a pure water environment.…”

“…(1) G pol are small numbers, much smaller than G pol , because the salt's concentration (2.18 M) is much lower than water's (∼55 M). The smaller number of potential neutral solute-ion versus solutewater interactions, coupled with ions being generally further away from the solute than water ( Figure S11 in the supplementary material), 38,55 result in the overall small G pol . (2) As G np in water results from a delicate balance repulsive cavity and attractive dispersion nonpolar terms, 30 shifts in this balance can lead to quite large G np , even similar in magnitude to the original G np .…”

Adsorption of cationic polyions onto a hydrophobic surface in the presence of Hofmeister salts

“…[43] and a simulation using the effective potential U i (z). In the upper panel we show the ionic profiles of the electrolyte NaCl, at concentration 0.2 M. The density profiles for Na + and Cl -are indistinguishable.…”

“…Following the pioneering work of Hofmeister, the same series has been observed in many other areas of science, ranging from electrochemistry, colloidal science [5,6], surfactant micellization [7], bacterial growth [8], surface and interfacial tensions [9,10], peptide bonds [11], microemulsions [12], etc. Recently, a theory was proposed that allows one to quantitatively predict the effect of Hofmeister ions on the surface [13][14][15] and the interfacial tensions [16,17] of electrolyte and acid solutions. In this paper we want to explore the effect that Hofmeister ions have on the interaction between cationic polyelectrolytes and a hydrophobic surface.…”