Dielectric and structural properties of aqueous nonpolar solute mixtures

Abstract

The dielectric properties and molecular structure of water mixtures with different nonpolar solutes (methane and noble gases) are studied using molecular dynamics. The water-water, water-solute, and solute-solute interactions are calculated using the combination of a polarizable potential [J. Li, Z. Zhou, and R. J. Sadus, J. Chem. Phys. 127, 154509 (2007)] for water plus the Lennard-Jones potential. The effect of solute size and concentration on the solubility of the system, hydrogen bonding, dielectric constant, and dipole moment are investigated over a temperature range of 278-750 K and solute percentage mole fractions up to 30%. Solute particles affect the structure of water, resulting in the compression of oxygen-oxygen and oxygen-hydrogen radial distribution functions. The influence of the solute extends both to relatively low concentrations and high temperatures. The coordination numbers of aqueous solutions of the nonpolar solutes appear to be proportional to the size of the solute particles. Our study shows the destructive influence of the nonpolar solute on both the tetrahedral water structure and hydrogen bond formation at solute concentrations greater than 30%. The presence of nonpolar particles typically decreases both the dielectric constant and dipole moment. The decrease of dielectric constant and water dipole moment is directly proportional to the solute concentration and temperature.

Atomistic water models: Aqueous thermodynamic properties from ambient to supercritical conditions

“…The H-bond network is most extensive at ambient conditions (25•C and 1 atm) when water molecules can form up to four hydrogen bonds. As the temperature and pressure increase, the average number of H-bonds per water molecule decreases (Shvab and Sadus, 2012). a n u s c r i p t 8 A model that captures the correct physical features of the system of interest is imperative for the successful molecular simulation of water and aqueous solutions (Vega and Abascal, 2011;Yigzawe and Sadus, 2013a).…”

“…Lie and Clementi (1986) argued that the MCY potential is too repulsive, which only allowed the computation of a small number of configurations used for fitting, and concluded that this compact configuration is the main reason for the prediction of high pressures. Among the good qualities of the MCY model are the correct representation of O-H and H-H RDFs (Shvab and Sadus, 2012). The model is important from a historical perspective, and it forms the basis for more advanced models that include bond flexibility (Lie and Clementi, 1986), three-body and polarization interaction terms (Niesar et al, 1990;Li et al, 2007).…”

“…The parameter ν is the nonadditive coefficient, which can be determined from experiment (Leonard and Barker, 1975). The theoretical background and rationale for using this formula is given elsewhere (Shvab and Sadus, 2012). The contribution of multi-body non-additive polarization interactions was obtained from (Coulson and Elsenberg, 1966) ,…”

“…The MCYna model is known for its very good representation of the dielectric constant and dipole moment of liquid water (Shvab and Sadus, 2012) and aqueous solutions (Shvab and Sadus, 2014).…”

Effect of Dissolution of Methane in Aqueous NaCl Solution: A Molecular Dynamics Study

“…The study on the effect of dissolution of methane in NaCl aqueous solution, or seawater, is an issue of great interest, because dissolution of methane into seawater may affect the earth environment. Though many molecular dynamics (MD) study dealing with methane hydrate have been performed [2], most of them are on the stand point of nucleation, or in the supercritical condition in pure water. In this study, we perform MD simulation of methane and NaCl solution similar concentration to seawater.…”