Monte Carlo simulation of the static properties of Hg solution in (O2, N2) gassed water

Abstract

Canonical Monte Carlo (CMC) simulations were carried out to investigate the influence of O2 and N2 gases on elemental mercury (Hg) solution in water. Particle–particle interactions were all modeled using Lennard–Jones potential function. To provide insight into the interaction of O2 and N2 gases with Hg atom in water, two independent mixtures Hg/(O2,H2O) and Hg/(N2,H2O) with the same bulk mole fraction of component (0.9956, 0.0023, 0.0023, 0.0021 for H2O, O2, N2 and Hg, respectively) were simulated at T=298K.The results show that Hg in water interacts favorably with O2 more than with N2. This is consistent with the hypothesis that stronger interaction of O2 gas with the mercury atom leads to a higher adsorption and lower dynamic structure compared with N2 gas. Independent simulation of Hg/(O2,H2O) and Hg/(N2,H2O) mixtures indicates that N2 gas molecules stay off the distance at which O2 interacts with Hg as the nearest neighboring distance. This procedure enables us to describe the structural properties of Hg⋯O2 and Hg⋯N2 in water at molecular scale which hints exploring techniques of the toxicity level of mercury contaminated water. Alternatively, comparison of potential of mean force indicated that Hg⋯O2 interaction exposes the free energy of −2.93kJmol−1 which is more stable pair interaction relative to Hg⋯H2O (−2.50kJmol−1) and Hg⋯N2 (−1.79kJmol−1).