Estimation of Vapor Pressures of Solvent plus Salt Systems with Quadratic Solvation Relationships

Abstract

The paper studies quadratic solvation models (QSMs) applied to the numerical simulation of the vapor pressures of solvent systems with a salt effect. Two useful general quadratic solvation relationships are presented within an integration framework, incorporating cumulative physical indices for components and boundary constraints, in conjunction with the vapor pressures of monomolecular fluids calculated from Antoine, Senol, Frost-Kalkwarf and Xiang-Tan equations. Literature data for the vapor pressures of 18 diverse binary (solvent + salt) and ternary (solvent 1 + solvent 2 + salt 3) vapor-liquid equilibrium systems are subjected to the statistical analysis of QSMs via a logarithmic-ratio objective function and cumulative frequency distribution. Essentially, the examined QSMs with twelve (QSM12) and six (QSM6) adjustable coefficients are quite accurate in yielding overall design factors (F-od) lower than 1.015 and 1.08, respectively. The concentration-dependent model (CM) also simulates precisely the observed data with F-od = 1.013 as far as salt effects are concerned. QSM12 models have proven reasonably successful in predicting the vapor pressures of ternary systems with a mean deviation of 2.2%.