Solubility prediction in mixed solvents: A combined molecular simulation and experimental approach

Abstract

We propose a simple method to predict solubility in mixed solvents, combining experimental data for solubility in pure solvents with non-ideal contributions obtained from molecular simulation. By evoking a well-established thermodynamic model for mixed solvent, we provide rationale and justification for this hybrid approach. We test the accuracy of the method for solubility prediction in two highly non-ideal mixtures, CO 2 in ethanol + water, and CH 4 in MDEA + water. Non-ideal behaviour in each system is characterised using molecular simulation across the full range of compositions and for temperatures covering the range 273.15 K-373.15 K. Comparison against experimental Henry's law constants for CO 2 and CH 4 gives mean absolute errors of 6.9% and 27%, respectively. We investigate the origin of non-ideal Henry's law behaviour in each of the mixed solvents by interrogating radial distribution functions from molecular simulation, finding increased association of CO 2 and CH 4 with the organic solvents at elevated temperatures.

High-Pressure Fluid-Phase Equilibria and Henry’s Constants of Supercritical Gases in Ammonia

“…Using the definition of Henry’s law and equating it with a rearrangement of eq , one obtains x i H i = x i ρ R T nobreak0em0.25em⁡ exp [ μ i r R T ] Canceling the mole fractions and imposing the condition of infinite dilution (lim x i →0 f̅ i ), the form mentioned by other investigators is derived. − H i = ρ s R T nobreak0em0.25em⁡ exp [ μ i r , ∞ R T ] Therein, lim x i →0 ρ = ρ s defines the pure saturated liquid solvent density and μ i r,∞ denotes the residual chemical potential of solute i at infinite dilution.…”

Henry’s Law Constant of Nitrogen, Oxygen, and Argon in Ternary Aqueous Alcoholic Solvent Mixtures

“…E.g., previous work of our group [18] has considered almost a hundred solute-solvent pairs with molecular simulation. More recently, Kvam and Sarkisov [19] provided a hybrid approach to obtain the gas solubility by combining pure solvent experimental data with non-ideal contributions from molecular simulation.…”

“…For example, a previous work of our group considered almost a hundred solute–solvent pairs with molecular simulation. More recently, Kvam and Sarkisov provided a hybrid approach to obtain the gas solubility by combining pure solvent experimental data with nonideal contributions from molecular simulation. On the other hand, we are not aware of a single publication dealing with the systematic prediction of the Henry’s law constant in ternary solvents.…”