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Title: Density Fluctuation in Aqueous Solutions and Molecular Origin of Salting-Out Effect for CO 2

Abstract

Using molecular dynamics simulation, we studied the density fluctuations and cavity formation probabilities in aqueous solutions and their effect on the hydration of CO 2. With increasing salt concentration, we report an increased probability of observing a larger than the average number of species in the probe volume. Our energetic analyses indicate that the van der Waals and electrostatic interactions between CO 2 and aqueous solutions become more favorable with increasing salt concentration, favoring the solubility of CO 2 (salting in). However, due to the decreasing number of cavities forming when salt concentration is increased, the solubility of CO 2 decreases. The formation of cavities was found to be the primary control on the dissolution of gas, and is responsible for the observed CO 2 salting-out effect. Finally, our results provide the fundamental understanding of the density fluctuation in aqueous solutions and the molecular origin of the salting-out effect for real gas.

Authors:
ORCiD logo [1]; ORCiD logo [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1406374
Report Number(s):
SAND-2017-11633J
Journal ID: ISSN 1520-6106; 658199; TRN: US1703134
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 121; Journal Issue: 51; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Ho, Tuan Anh, and Ilgen, Anastasia. Density Fluctuation in Aqueous Solutions and Molecular Origin of Salting-Out Effect for CO2. United States: N. p., 2017. Web. doi:10.1021/acs.jpcb.7b09215.
Ho, Tuan Anh, & Ilgen, Anastasia. Density Fluctuation in Aqueous Solutions and Molecular Origin of Salting-Out Effect for CO2. United States. doi:10.1021/acs.jpcb.7b09215.
Ho, Tuan Anh, and Ilgen, Anastasia. Thu . "Density Fluctuation in Aqueous Solutions and Molecular Origin of Salting-Out Effect for CO2". United States. doi:10.1021/acs.jpcb.7b09215.
@article{osti_1406374,
title = {Density Fluctuation in Aqueous Solutions and Molecular Origin of Salting-Out Effect for CO2},
author = {Ho, Tuan Anh and Ilgen, Anastasia},
abstractNote = {Using molecular dynamics simulation, we studied the density fluctuations and cavity formation probabilities in aqueous solutions and their effect on the hydration of CO2. With increasing salt concentration, we report an increased probability of observing a larger than the average number of species in the probe volume. Our energetic analyses indicate that the van der Waals and electrostatic interactions between CO2 and aqueous solutions become more favorable with increasing salt concentration, favoring the solubility of CO2 (salting in). However, due to the decreasing number of cavities forming when salt concentration is increased, the solubility of CO2 decreases. The formation of cavities was found to be the primary control on the dissolution of gas, and is responsible for the observed CO2 salting-out effect. Finally, our results provide the fundamental understanding of the density fluctuation in aqueous solutions and the molecular origin of the salting-out effect for real gas.},
doi = {10.1021/acs.jpcb.7b09215},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
number = 51,
volume = 121,
place = {United States},
year = {Thu Oct 26 00:00:00 EDT 2017},
month = {Thu Oct 26 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on October 26, 2018
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