Effect of Ion Valency on the Properties of the Carbon Dioxide-Methane-Brine System

Yafan Yang, Mohd Fuad Anwari Che Ruslan, Arun Kumar Narayanan Nair*, Shuyu Sun

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)2719-2727
Number of pages9
JournalJournal of Physical Chemistry B
Issue number12
StatePublished - Mar 28 2019

Bibliographical note

Publisher Copyright:
Copyright © 2019 American Chemical Society.

ASJC Scopus subject areas

  • Materials Chemistry
  • Surfaces, Coatings and Films
  • Physical and Theoretical Chemistry


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