TY - JOUR
T1 - Effect of Ion Valency on the Properties of the Carbon Dioxide-Methane-Brine System
AU - Yang, Yafan
AU - Che Ruslan, Mohd Fuad Anwari
AU - Narayanan Nair, Arun Kumar
AU - Sun, Shuyu
N1 - Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/3/28
Y1 - 2019/3/28
N2 - Molecular dynamics simulations and theoretical analysis were carried out to study the bulk and interfacial properties of carbon dioxide-methane-water and carbon dioxide-methane-brine systems under geological conditions. The density gradient theory with the bulk phase properties estimated using the cubic-plus-association (CPA) equation of state (EoS) can well describe the increase in the interfacial tension (IFT) of the CO 2 -water system in the presence of methane. The theoretical estimates of species mole fractions in the carbon dioxide-methane-water system are in good quantitative agreement with the experimental results. Furthermore, simulations of carbon dioxide-methane-brine system show that the IFT of the CaCl 2 case is generally higher than that of the NaCl case. This is probably due to the stronger hydration of Ca 2+ ions and their stronger repulsion from the interface compared to Na + . While the overall shape of the ionic profiles is not much affected by the ion type, the water profiles show a local enrichment at the interface in the system with CaCl 2 . In contrast to the case of NaCl, the slopes of the plots of IFT vs CaCl 2 concentration are dependent on temperature. Species mole fractions in the carbon dioxide-methane-brine system predicted by combining the CPA EoS with the Debye-Hückel electrostatic term are in good agreement with simulation results.
AB - Molecular dynamics simulations and theoretical analysis were carried out to study the bulk and interfacial properties of carbon dioxide-methane-water and carbon dioxide-methane-brine systems under geological conditions. The density gradient theory with the bulk phase properties estimated using the cubic-plus-association (CPA) equation of state (EoS) can well describe the increase in the interfacial tension (IFT) of the CO 2 -water system in the presence of methane. The theoretical estimates of species mole fractions in the carbon dioxide-methane-water system are in good quantitative agreement with the experimental results. Furthermore, simulations of carbon dioxide-methane-brine system show that the IFT of the CaCl 2 case is generally higher than that of the NaCl case. This is probably due to the stronger hydration of Ca 2+ ions and their stronger repulsion from the interface compared to Na + . While the overall shape of the ionic profiles is not much affected by the ion type, the water profiles show a local enrichment at the interface in the system with CaCl 2 . In contrast to the case of NaCl, the slopes of the plots of IFT vs CaCl 2 concentration are dependent on temperature. Species mole fractions in the carbon dioxide-methane-brine system predicted by combining the CPA EoS with the Debye-Hückel electrostatic term are in good agreement with simulation results.
UR - http://www.scopus.com/inward/record.url?scp=85063076005&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.8b12033
DO - 10.1021/acs.jpcb.8b12033
M3 - Article
C2 - 30843699
AN - SCOPUS:85063076005
SN - 1520-6106
VL - 123
SP - 2719
EP - 2727
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 12
ER -