TY - JOUR
T1 - Theory of Gas Solubility and Hydrophobic Interaction in Aqueous Electrolyte Solutions
AU - Okamoto, Ryuichi
AU - Koga, Kenichiro
N1 - Funding Information:
The authors are grateful to Hiroyuki Katsuto, Tomonari Sumi, and Akira Onuki for fruitful discussions. R.O. thanks Maarten Biesheuvel for his kind correspondence. This work was supported by JSPS KAKENHI (grant nos. 18K03562, 18KK0151, and 20H02696).
Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.
PY - 2021/11/25
Y1 - 2021/11/25
N2 - Ion-specific effects on the solubility of nonpolar solutes and on the solute-solute hydrophobic interaction in aqueous electrolyte solutions are studied on the basis of a continuum theory that incorporates the excluded volume of the molecules using the four-component (water, cations, anions, and solutes) Boublĺk-Mansoori-Carnahan-Starling-Leland model and ion hydration (electrostriction) using the Born model. We examine how the ordering of ions in the salt effect on the solubility as measured by the Sechenov coefficient KS changes with varying sizes of ions and solutes. Our calculation reproduces the general trend of experimentally measured KS and also provides insight into the irregular behavior of KS for lithium ion. The correlation between KS and the salt effect on the hydrophobic interaction that has been pointed out earlier is accounted for by an explicit connection between KS and the salt-enhanced-association coefficient CI in the expansion of the second osmotic virial coefficient B(ns) = B(0) - CIns + ··· in powers of the salt density ns at fixed pressure and temperature. The quadratic relation CI≈KS2/4 is derived for ions and solutes that are not very large.
AB - Ion-specific effects on the solubility of nonpolar solutes and on the solute-solute hydrophobic interaction in aqueous electrolyte solutions are studied on the basis of a continuum theory that incorporates the excluded volume of the molecules using the four-component (water, cations, anions, and solutes) Boublĺk-Mansoori-Carnahan-Starling-Leland model and ion hydration (electrostriction) using the Born model. We examine how the ordering of ions in the salt effect on the solubility as measured by the Sechenov coefficient KS changes with varying sizes of ions and solutes. Our calculation reproduces the general trend of experimentally measured KS and also provides insight into the irregular behavior of KS for lithium ion. The correlation between KS and the salt effect on the hydrophobic interaction that has been pointed out earlier is accounted for by an explicit connection between KS and the salt-enhanced-association coefficient CI in the expansion of the second osmotic virial coefficient B(ns) = B(0) - CIns + ··· in powers of the salt density ns at fixed pressure and temperature. The quadratic relation CI≈KS2/4 is derived for ions and solutes that are not very large.
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U2 - 10.1021/acs.jpcb.1c08050
DO - 10.1021/acs.jpcb.1c08050
M3 - Article
C2 - 34756051
AN - SCOPUS:85119450919
SN - 1520-6106
VL - 125
SP - 12820
EP - 12831
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 46
ER -