Excess Gibbs free energy models for studying ionic liquid-H2O binary system

In this work, the excess Gibbs free energy models, i.e., non-random two-liquid (NRTL) model, electrolyte NRTL model, and electrolyte NRTL model including new strategies (association or hydration), were used to describe the macroscale properties and interpret the microstructure, clarifying the role of association and hydration in model development, and the enthalpy of mixing of three imidazolium-based IL-H2O systems containing the same cation but different sizes of anions, i.e., Cl−, Br−, and I− were measured for the first time to provide systematic data for model development. The models were developed and evaluated based on the newly measured data and the osmotic coefficient from the literature. The model reflecting the intrinsic mechanism of dissociation and hydration competition gives the best modeling results. The real ionic strength predicted from the identified model was quantitatively correlated with the electrical conductivities.

Thermodynamic, structural, surface and transport properties of Au-Ni liquid alloy at 1150 K

Thermodynamic, structural, surface, and transport properties of Au-Ni liquid alloy at 1150 K were computed using different theoretical approaches. The thermodynamic properties, such as excess Gibbs free energy of mixing, enthalpy of mixing, activity and excess entropy of mixing, and structural properties, such as concentration fluctuation in long-wavelength limit and Warren-Cowley short-range order parameter were computed in the framework of Flory’s model. The effect of positive and negative values of the interchange energy parameter on the excess Gibbs free energy of mixing and concentration fluctuation in the long-wavelength limit was also observed. The surface tension and surface concentration of the system were calculated using Butler’s model. In the transport property, the viscosity of the system was calculated using Kaptay and Budai-Benko-Kaptay (BBK) models. BIBECHANA 18 (2021) 184-192

Thermodynamic Study on Density and Viscosity of Binary Mixtures of Ethyl acetoacetate with (C4-C9) Aliphatic Ketones at (303.15 and 308.15) K

Investigation on Density (ρ) and viscosity (η) of various binary mixtures of ethylacetoacetate and straight chain aliphatic ketones (butan-2-one, pentan-2- one, hexan-2-one, heptan-2-one, octan-2-one and nonan2-one) have been carried out over the entire solvents composition range at temperatures of 303.15K and 308.15K. From the data obtained, the excess molar volumes (V E ), the excess viscosity (η E ) and excess Gibbs free energy of activation for viscous flow (ΔG*E) have been calculated from the experimental density and viscosity measurements at the working temperatures. Excess molar volumes, V E results are negative and positive over the entire range of mole fractions and become more positive as the chain length increases. The excess viscosities, η E were both positive and negative over the entire mole fraction range. While the observed excess Gibbs free energies of activation of viscous flow, ΔG*E data are positive throughout the entire mole fraction range of solvents composition at all investigated temperatures. These observed results of the excess functions have been interpreted in terms of possible molecular interactions in the binary mixtures.

Assessment of the SM12, SM8, and SMD Solvation Models for Predicting Limiting Activity Coefficients at 298.15 K

The SMx (x = 12, 8, or D) universal solvent models are implicit solvent models which using electronic structure calculations can compute solvation free energies at 298.15 K. While solvation free energy is an important thermophysical property, within the thermodynamic modeling of phase equilibrium, limiting (or infinite dilution) activity coefficients are preferred since they may be used to parameterize excess Gibbs free energy models to model phase equilibrium. Conveniently, the two quantities are related. Therefore the present study was performed to assess the ability to use the SMx universal solvent models to predict limiting activity coefficients. Two methods of calculating the limiting activity coefficient where compared: (1) the solvation free energy and self-solvation free energy were both predicted and (2) the self-solvation free energy was computed using readily available vapor pressure data. Overall the first method is preferred as it results in a cancellation of errors, specifically for the case in which water is a solute. The SM12 model was compared to both the Universal Quasichemical Functional-group Activity Coefficients (UNIFAC) and modified separation of cohesive energy density (MOSCED) models. MOSCED was the highest performer, yet had the smallest available compound inventory. UNIFAC and SM12 exhibited comparable performance. Therefore further exploration and research should be conducted into the viability of using the SMx models for phase equilibrium calculations.

Assessment of the SM12, SM8, and SMD Solvation Models for Predicting Limiting Activity Coefficients at 298.15 K

The SM<i>x</i> (<i>x</i>= 12, 8, or D) universal solvent models are implicit solvent models which using electronic structure calculations can compute solvation free energies at 298.15 K. While solvation free energy is an important thermophysical property, within the thermodynamic modeling of phase equilibrium, limiting (or infinite dilution) activity coefficients are preferred since they may be used to parameterize excess Gibbs free energy models to model phase equilibrium. Conveniently, the two quantities are related. Therefore the present study was performed to assess the ability to use the SM<i>x</i> universal solvent models to predict limiting activity coefficients. Two methods of calculating the limiting activity coefficient where compared: 1) The solvation free energy and self-solvation free energy were both predicted and 2) the self-solvation free energy was computed using readily available vapor pressure data. Overall the first method is preferred as it results in a cancellation of errors, specifically for the case in which water is a solute. The SM12 model was compared to both UNIFAC and MOSCED. MOSCED was the highest performer, yet had the smallest available compound inventory. UNIFAC and SM12 exhibited comparable performance. Therefore further exploration and research should be conducted into the viability of using the SM<i>x</i> models for phase equilibrium calculations.

Assessment of the SM12, SM8, and SMD Solvation Models for Predicting Limiting Activity Coefficients at 298.15 K

The SM<i>x</i> (<i>x</i>= 12, 8, or D) universal solvent models are implicit solvent models which using electronic structure calculations can compute solvation free energies at 298.15 K. While solvation free energy is an important thermophysical property, within the thermodynamic modeling of phase equilibrium, limiting (or infinite dilution) activity coefficients are preferred since they may be used to parameterize excess Gibbs free energy models to model phase equilibrium. Conveniently, the two quantities are related. Therefore the present study was performed to assess the ability to use the SM<i>x</i> universal solvent models to predict limiting activity coefficients. Two methods of calculating the limiting activity coefficient where compared: 1) The solvation free energy and self-solvation free energy were both predicted and 2) the self-solvation free energy was computed using readily available vapor pressure data. Overall the first method is preferred as it results in a cancellation of errors, specifically for the case in which water is a solute. The SM12 model was compared to both UNIFAC and MOSCED. MOSCED was the highest performer, yet had the smallest available compound inventory. UNIFAC and SM12 exhibited comparable performance. Therefore further exploration and research should be conducted into the viability of using the SM<i>x</i> models for phase equilibrium calculations.

Assessment of the SM12, SM8, and SMD Solvation Models for Predicting Limiting Activity Coefficients at 298.15 K

The SM<i>x</i> (<i>x</i>= 12, 8, or D) universal solvent models are implicit solvent models which using electronic structure calculations can compute solvation free energies at 298.15 K. While solvation free energy is an important thermophysical property, within the thermodynamic modeling of phase equilibrium, limiting (or infinite dilution) activity coefficients are preferred since they may be used to parameterize excess Gibbs free energy models to model phase equilibrium. Conveniently, the two quantities are related. Therefore the present study was performed to assess the ability to use the SM<i>x</i> universal solvent models to predict limiting activity coefficients. Two methods of calculating the limiting activity coefficient where compared: 1) The solvation free energy and self-solvation free energy were both predicted and 2) the self-solvation free energy was computed using readily available vapor pressure data. Overall the first method is preferred as it results in a cancellation of errors, specifically for the case in which water is a solute. The SM12 model was compared to both UNIFAC and MOSCED. MOSCED was the highest performer, yet had the smallest available compound inventory. UNIFAC and SM12 exhibited comparable performance. Therefore further exploration and research should be conducted into the viability of using the SM<i>x</i> models for phase equilibrium calculations.

Equation of state of the fluid system H2O-CO2-CaCl2 and properties of fluid phases at P-T parameters of the middle and lower crust

A numerical thermodynamic model is proposed for one of the most important geological fluid system – triple system H2O-CO2-CaCl2 at P-T conditions of the middle and lower crust, as well as for the crust-mantle boundary. The model is based on the equation for concentration dependence of the excess Gibbs free energy, proposed earlier, and for the first time obtained P-T dependencies of the coefficients of the equation of state (EOS) expressed via molar volumes of the components. The EOS allows predictions of the properties of the fluid, participating in the majority of the processes of depth petrogenesis: its phase state (homogeneous or multi-phase), densities of the fluid phases, concentrations of the components in the co-existing phases, and chemical activities of the components. The model precisely reproduces all available experimental data on the phase state of the ternary fluid system H2O-CO2-CaCl2 in the ranges of temperature 773.15–1073.15 K and pressures 0.1-0.9 GPa and allows, as well, correct application of the EOS beyond the experimentally studied domain of temperatures and pressures – namely up to P = 2 GPa and up to T = 1673.15 K. The possibility of the correct extrapolation of our EOS is ensured by using the parametrization of P-T dependencies via the molar volume of water. The latter remains in the experimental domain of values or very near to its boundaries, when increasing temperatures and pressures.

Experimental Data of Fluid Phase Equilibria- Correlation and Prediction Models: A Review

The examples of phase equilibria in binary systems, solid/liquid (SLE), liquid/liquid (LLE), vapor/liquid (VLE), as well as liquid/liquid equilibria in ternary systems mainly containing ionic liquids (ILs), or the infragrance materials, or pharmaceuticals with molecular organic solvents, such as an alcohol, or water, or hydrocarbons, are presented. The most popular correlation methods of the experimental phase equilibrium data are presented, related to the excess Gibbs free energy models such as Wilson, universal-quasichemical, UNIQUAC and non-random two-liquid model, NRTL as well as several popular theories for the modeling of the phase equilibria and excess molar enthalpy, HE in binary or ternary mixtures are presented: the group contribution method (Mod. UNIFAC) and modified UNIFAC model for pharmaceuticals and lattice theory based on non-random hydrogen bonding (NRHB). The SLE, LLE, or VLE and HE of these systems may be described by the Perturbed-Chain Polar Statistical Associating Fluid Theory (PC-SAFT), or a Conductor-like Screening Model for Real Solvents (COSMO-RS). The examples of the application of ILs as extractants for the separation of aromatic hydrocarbons from alkanes, sulfur compounds from alkanes, alkenes from alkanes, ethylbenzene from styrene, butan-1-ol from water phase, or 2-phenylethanol (PEA) from water are discussed on the basis of previously published data. The first information about the selectivity of extrahent for separation can be obtained from the measurements of the limiting activity coefficient measurements by the gas–liquid chromatography technique. This review outlines the main research work carried out over the last few years on direct measurements of phase equilibria, or HE and limiting activity coefficients, the possibility of thermodynamic modeling with emphasis on recent research achievements and potential for future research.

Excess Molar Volume Calculation and Viscosity Deviation and Excess Gibbs Energy for Binary Solution of 1- Propanol with Butyl Acetate at Temperatures (40,50,60) 0C

In this research, the solubility Process of the binary liquid solution(1-Propanol and butyl acetate) were studied at temperature(40,50.60)0C. Densities ρ by pycnometer method and viscosity ƞ by OSTWALD tube that calibrated with distilled water was measured. Then excess molar volume was calculated of pure component and its mixtures that was prepared over the entire mole fraction range. It has been observed that excess molar volumes values were negative at all temperatures. After that, the deviation in viscosity ∆ ƞ and Excess Gibbs free energy ∆GE was determined and it has been observed that it takes negative values at all temperatures. Excess molar volume, deviation in viscosity, excess Gibbs free energy were correlated with Redlich-Kister equation Type polynomial and the showed an accepted standard deviation between the experimental and calculated values it has been shown the effect of Hydrogen bonds formation and the spherical shape for the molecules and its size on the excess thermodynamic properties.