Thermodynamics and kinetics of ion speciation in supercritical aqueous solutions: A molecular based study.

摘要

Molecular simulation of infinitely dilute NaCl aqueous solutions are performed to study the Na(sup +)/Cl(sup -) ion pairing in a polarizable and a nonpolarizable solvent at supercritical conditions. The Simple Point Charge, Pettitt-Rossky, and Fumi-Tosi models for the water-water, ion-water, and ion-ion interactions are used in determining the degree of dissociation, its temperature and density dependence, and the kinetics of the interconversion between ion-pair configurations in a nonpolarizable medium. To assess the effect of the solvent polarizability on the stability of the ion-pair configurations, we replace the Simple Point Charge by the Polarizable Point Charge water model and determine the anion-cation potential of mean force at T(sub r)=1.20 and (rho)(sub r)=1.5.