Solubility of Nitrogen in Methane, Ethane, and Mixtures of Methane and Ethane at Titan-Like Conditions: A Molecular Dynamics Study
by Kumar, Pradeep; Chevrier, Vincent F.
We have studied the temperature dependence of the solubility of nitrogen in methane, ethane, and mixtures of methane and ethane using vapor-liquid equilibrium simulations of binary and ternary mixtures of nitrogen, methane, and ethane for a range of temperatures between 90 and 110 K at a pressure of 1.5 atm, thermodynamic conditions that may exist on the Saturn's giant moon, Titan. We find that (i) the solubility of nitrogen in both methane and ethane decreases with increasing temperature; (ii) the solubility of nitrogen in methane is much larger compared to that in ethane at low temperatures, and (iii) solubility of nitrogen in a ternary mixture of methane, ethane, and nitrogen increases upon increasing the mole fraction of methane. Our results are in quantitative agreement with the recent experimental measurement of the solubility of nitrogen in methane, ethane, and a mixture of methane and ethane. Furthermore, we find a strong temperature-dependent surface adsorption of nitrogen at the nitrogen-hydrocarbon interface, previously unknown. We have also investigated surface tension of the gas-liquid interface and find that it decreases upon decreasing the temperature below 100 K for both nitrogen-methane and nitrogen-ethane binary systems. Moreover, we find that the interfacial layer of adsorbed nitrogen and ethane shows a preferential orientational ordering at the interface.
- Journal
- ACS Earth and Space Chemistry
- Volume
- 4
- Issue
- 2
- Year
- 2020
- Start Page
- 241-248
- URL
- https://dx.doi.org/10.1021/acsearthspacechem.9b00289
- ISBN/ISSN
- 2472-3452
- DOI
- 10.1021/acsearthspacechem.9b00289