Vapor–liquid equilibria of the carbon dioxide (CO2) + 2,2-dichloro-1,1,1-trifluoroethane (R123) system and carbon dioxide (CO2) + 1-chloro-1,2,2,2-tetrafluoroethane (R124) system

Binary vapor–liquid equilibrium data were measured for the carbon dioxide (CO₂) + 2,2-dichloro-1,1,1-trifluoroethane (R123) system and the carbon dioxide (CO₂) + 1-chloro-1,2,2,2-tetrafluoroethane (R124) system at temperature from 313.15 to 333.15 K. These experiments were carried out with a circulating-type apparatus with on-line gas chromatography. The experimental data were correlated well by Peng–Robinson equation of state using the Wong–Sandler mixing rules.     

The solubility of water in mixtures of dimethyl ether and carbon dioxide

This paper reports measurements of the solubility of water in liquid and supercritical fluid mixtures of dimethyl ether and carbon dioxide. The measurements were made by extracting water under saturation conditions using premixed liquid dimethyl ether–carbon dioxide mixtures. Results are reported for temperatures of 313.8 K and 333.3 K at 9.0 MPa and 15.0 MPa. Results are fitted to the Peng–Robinson cubic equation of state with mixing rules according to Wong and Sandler, using binary interaction parameters fitted to the literature data for the respective binary systems: dimethyl ether–water; dimethyl ether–carbon dioxide; and carbon dioxide–water. Liquid densities for dimethyl ether–carbon dioxide mixtures, measured using a coriolis flow instrument, are also reported.     

Phase behavior of the system hyperbranched polyglycerol + methanol + carbon dioxide

Phase equilibrium data have been measured for the ternary system hyperbranched polyglycerol + methanol + carbon dioxide at temperatures of 313–450 K and pressures up to 13.5 MPa. Phase changes were determined according to a synthetic method using the Cailletet setup. At elevated temperatures the system shows a liquid–liquid–vapor region with lower solution temperatures. Besides the vapor–liquid and liquid–liquid equilibria, the vapor–liquid to vapor–liquid–liquid and vapor–liquid–liquid to liquid–liquid phase boundaries are reported at different polymer molar masses and can serve as test sets for thermodynamic models. A distinct influence of the polymer molar mass on the vapor–liquid equilibrium can be noticed and indicates the existence of structural effects due to the polymer branching. Modeling the systems with the PCP-SAFT equation of state confirms these findings.     

High-pressure phase behavior of CO2 + 1-butyl-3-methylimidazolium chloride system

The phase behavior of carbon dioxide (CO₂) and the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) was measured and correlated at high pressures up to ∼40 MPa and at temperatures between 353.15 K and 373.15 K. The solubility data of CO₂ in [bmim][Cl] were obtained by observing the bubble point pressure at specific temperatures. A variable-volume view cell, which is a high-pressure equilibrium apparatus, was used to measure the CO₂ + [bmim][Cl] system solubility under varying pressure and temperature conditions. In addition, liquid–liquid–vapor (LLV) three-phase behavior was investigated using the equilibrium cell to be able to determine the classification of phase-behavior type by Scott and Van Konynenburg. Based on the LLV phase behavior, this system most likely has type III phase-behavior which is common for IL + CO₂ systems. The resulting data showed that CO₂ dissolved well in the IL at low CO₂ concentrations, but that the pressure derivative of CO₂ solubility dramatically decreased as the mole fraction of CO₂ was increased. The experimental data were well fitted by the Peng–Robinson equation of state with a quadratic mixing rule and cubic parameters estimated by the Joback method.     

Measurement and correlation of solubility of artemisinin in supercritical carbon dioxide

Artemisinin is an effective antimalarial drug isolated from the herbal medicine Artemisia annua L. Supercritical fluid extraction is an environment-friendly method for the extraction of artemisinin. In this work, the solubility of artemisinin in supercritical carbon dioxide was determined by static method at three temperatures of 313 K, 323 K, 333 K and pressures from 11 to 31 MPa. The range of experimental solubility data was from 0.498 × 10⁻³ to 2.915 × 10⁻³ mol/mol under the above-mentioned conditions. Two density-based models (Chrastil and Mendez–Santiago–Teja models) were selected to correlate the experimental data of this work, and the average absolute relative deviation (AARD) was 8.32% and 8.33%, respectively. The correlation results showed good agreement with the experimental data.     

Acid gases partial pressures above a 50 wt% aqueous methyldiethanolamine solution: Experimental work and modeling

Aqueous amine solutions are widely used in the industry for acid gas removal. In order to treat natural gas or refinery process streams, an accurate knowledge of solubility data of carbon dioxide, hydrogen sulfide and other sulfur species in aqueous amine solutions is required. In this paper, new equilibrium measurements on 50 wt% aqueous methyldiethanolamine solution with CO₂ and H₂S have been produced. A simple way to correlate the data has been searched and found. First, a model proposed by Posey et al. in 1996, then a Deshmukh–Mather model are used to correlate “vapor–liquid” equilibria. The Posey et al. model lacks accuracy to represent the experimental data, especially for high loadings. The Deshmukh–Mather model shows good agreement as long as the total loading (H₂S + CO₂) does not reach 1.0.     

Density-functional study for the NOx (x = 1, 2) dissociation mechanism on the Cu(1 1 1) surface

Spin-polarized density functional theory calculation is employed to study the adsorption and dissociation of NO₂ molecule on Cu(1 1 1) surface. It is shown that the most favorable adsorption structure is the NO₂ (T,T-O-,O′-nitrito) configuration which has an adsorption energy of −1.49 eV. The barriers for step-wise NO₂ dissociation reaction, NO_2(g) → N_(a) + 2O_(a), are 1.05 (for O–N–O bond activation), and 2.08 eV (for N–O bond activation), respectively, and the entire process is 0.6 eV exothermic. The energetics of single N–O dissociation with and without the presence of N atom or O atom on the surface are also calculated. The results indicate that in the presence of O atom on Cu(1 1 1) surface would raise the N–O dissociation barrier, whereas in the presence of N atom decrease it. The interaction nature between adsorbates and substrate is analyzed by the local density of states (LDOS) calculation.     

Microscopic phase behavior of supercritical carbon dioxide + non-ionic surfactant + water systems at elevated pressures

The microscopic phase behavior of the supercritical carbon dioxide (scCO₂) + polyethylene oxide-2,6,8-trimethyl-4-nonyl ether (TMN) + water systems at about 3 wt% of TMN were investigated using a synthetic method with a microscope. The two types of TMN (TMN-3 and TMN-10) used in this work had molecular weight distributions caused by the distribution of the number of ethylene oxide groups. Two different types of phase transition were observed when pressure was decreased gradually at a constant temperature from the high pressure at which the transparent phase was observed to the low pressure at which the separate vapor–liquid phases were observed for the scCO₂ + TMN-3 + water system at 3 wt% of TMN-3. The transparent phase was colorless under all experimental conditions and the phase transition from a transparent phase to a turbidity phase with small, dispersed droplets was observed at the higher side phase transition (higher phase transition pressure). As the pressure continued to decrease, another phase transition was observed from the phase with small droplets to a state with an accelerating aggregation of droplets (lower phase transition pressure). In the turbidity phase between the higher and the lower phase transition, the degree of turbidity became higher with decreasing pressure. On the other hand, in the phase observed below the lower phase transition, a new liquid phase adhered to the sapphire windows and the wall inside the optical cell.     

High-pressure phase equilibria in the carbon dioxide + pyrrole system

Liquid–vapor (LV) and liquid–liquid (LL) phase equilibria in the carbon dioxide + pyrrole system were measured at temperatures between 313 K and 333 K, and pressures between 8.4 MPa and 15.1 MPa. The data were used to predict the overall phase behavior of the system using the Patel–Teja equation of state and the Mathias–Klotz–Prausnitz mixing rules with two temperature-independent parameters. The calculations suggest that the carbon dioxide + pyrrole system may exhibit type IV phase behavior according to the classification of Scott and van Konynenburg.     

Measurement and prediction of tie-line data for mixtures of (water + 1-propanol + diisopropyl ether): LLE diagrams as a function of temperature

Tie-line data for ternary system of (water + 1-propanol + diisopropyl ether (DIPE)) were determined at T = (298.2, 308.2 and 313.2) K under atmospheric conditions. The ternary system exhibited type-I LLE behavior, as (DIPE + water) is the only liquid pair that is partially miscible. The experimental data for this system were predicted with the UNIFAC model with a root mean square deviation of 2.64%. The reliability of the experimental tie-line data was determined through the Othmer–Tobias and Hand plots. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents. The influence of temperature effect on the equilibrium characteristics and separation factor was found to be significant at the temperatures studied.     

Quinary liquid–liquid equilibria for mixtures of nonane + undecane + two pairs of aromatics (benzene/toluene/m-xylene) + sulfolane at 298.15 and 313.15 K

In this work, liquid–liquid equilibrium data were measured for three quinary mixtures (nonane + undecane + benzene + toluene + sulfolane), (nonane + undecane + benzene + m-xylene + sulfolane) and (nonane + undecane + toluene + m-xylene + sulfolane) at 298.15 and 313.15 K and ambient pressure. The experimental LLE data were determined by using a jacketed glass cell with temperature controlled. The quantitative analysis was performed by using a Varian gas chromatograph equipped with a flame ionization detector and a SPB™-1 column. The experimental quinary liquid–liquid equilibrium data have been satisfactorily correlated by using NRTL and UNIFAC-LLE models. The calculated values based on the NRTL model were found to be in a better agreement with the experiment than those based on the UNIFAC-LLE model.     

Measurement and correlation of vapor–liquid equilibria for methanol + methyl laurate and methanol + methyl myristate systems near critical temperature of methanol

A flow-type method was adopted to measure the vapor–liquid equilibria for methanol + methyl laurate and methanol + methyl myristate systems at 493–543 K, near the critical temperature of methanol (T_c = 512.64 K), and 2.16–8.49 MPa. The effect of temperature and fatty acid methyl esters to the phase behavior was discussed. The mole fractions of methanol in liquid phase are almost the same for both systems. In vapor phase, the mole fractions of methanol are very close to unity at all temperatures. The present vapor–liquid equilibrium data were correlated by PRASOG. A binary parameter was introduced to the combining rule of size parameter. The binary parameters of methanol + fatty acid methyl ester systems were determined by fitting the present experimental data. The correlated results are in good agreement with the experimental data. The vapor–liquid equilibria for methanol + methyl laurate + glycerol and methanol + methyl myristate + glycerol ternary systems were also predicted using the methanol + fatty acid methyl ester binary parameters. The mole fractions of methanol in vapor phase are around unity even if glycerol is included in the systems.     

Solubility and density measurements of palmitic acid in supercritical carbon dioxide + alcohol mixtures

Solubility data of palmitic acid (hexadecanoic acid) in supercritical carbon dioxide were measured in the pressure range from 10 to 25 MPa at temperatures of 313 and 318 K. Densities for this binary mixture in the homogeneous phase and at saturation conditions were measured in the same range of temperature. The influence of 3 and 6 mol% ethanol and 2-propanol as co-solvent on the solubility and density data for the CO₂ + palmitic acid mixture was also determined at 313 K. Measurements were carried out in a static-synthetic sapphire cell coupled to a vibrating-tube densitometer. The self-consistency of the data was tested according to the density-based models proposed by Mendez-Santiago and Teja.     

Isobaric vapor–liquid equilibria for the quaternary reactive system: Ethanol + water + ethyl lactate + lactic acid at 101.33 kPa

Isobaric vapor–liquid equilibrium (VLE) data of the reactive quaternary system ethanol (1) + water (2) + ethyl lactate (3) + lactic acid (4) have been determined experimentally. Additionally, the reaction equilibrium constant was calculated for each VLE experimental data. The experimental VLE data were correlated using the UNIQUAC equation to describe the chemical and phase equilibria simultaneously. For some of the non-reactive binary systems, UNIQUAC binary interaction parameters were obtained from the literature. The rest of the binary UNIQUAC parameters were obtained by correlating the experimental quaternary VLE data obtained in this work. A maximum pressure azeotrope at high water concentration for the binary reactive system ethyl lactate + water has been calculated.     

Measurements for the solid solubilities of antipyrine, 4-aminoantipyrine and 4-dimethylaminoantipyrine in supercritical carbon dioxide

The solid solubilities of three active pharmaceutical ingredients (APIs) of antipyrine, 4-aminoantipyrine and 4-dimethylaminoantipyrine in supercritical carbon dioxide were measured by a semi-flow apparatus. The experiments were taken at 308.2, 318.2 and 328.2 K. The pressure range was from 10 to 22 MPa. These experimental results were correlated by the semi-empirical models of Mendez–Santiago–Teja and Chrastil. A solution model was also employed to fit the measured data. The average absolute relative deviation in solid solubility from semi-empirical models was 4–6%, and that from the solution model was 5–8%. The measured data satisfied the self-consistency test, and the parameters in the semi-empirical models are feasible for data extrapolation.     

Phase equilibria of (water + levulinic acid + dibasic esters) ternary systems

Liquid–liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + levulinic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at 298.15 K and 101.3 ± 0.7 kPa. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. The LLE data were correlated fairly well with UNIQUAC and NRTL models, indicating the reliability of the UNIQUAC and NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (α = 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents.     

Vapor–liquid equilibrium data for the binary systems in the process of synthesizing diethyl carbonate

Vapor–liquid equilibrium data for the binary systems of carbon monoxide (CO) + diethyl carbonate (DEC) and carbon monoxide + ethyl acetate (EA) were measured at temperatures of 293.2 K, 313.2 K and 333.2 K and the elevated pressures up to 12.00 MPa. The measurements were carried out in a cylindrical autoclave with a moveable piston and an observation window. The experimental data were correlated using the Peng–Robisom (PR) equation of state (EOS) and Peng–Robinson–Stryjek–Vera (PRSV) equation of state with the two-parameter van der Waals II or Panagiotopoulos–Reid mixing rule. The interaction parameters were obtained while correlating. The comparison between calculation results and experimental data indicated that the method of PRSV equation of state with van der Waals II produced the better correlated results.     

Liquid–liquid equilibria for quaternary mixtures of nonane + undecane + (benzene or toluene or m-xylene) + sulfolane at 298.15 and 313.15 K

Liquid–liquid equilibrium (LLE) data were measured for three quaternary systems containing sulfolane, nonane + undecane + benzene + sulfolane, nonane + undecane + toluene + sulfolane and nonane + undecane + m-xylene + sulfolane, at T = 298.15 and 313.15 K and ambient pressure. The experimental quaternary liquid–liquid equilibrium data have been satisfactorily represented by using NRTL and UNIFAC-LLE models for the activity coefficient. The calculated compositions based on the NRTL model were found to in a better agreement with the experiment than those based on the UNIFAC-LLE model.     

Isothermal vapor–liquid equilibrium at 303.15 K and excess molar volumes at 298.15 K for the ternary system of propyl vinyl ether + 1-propanol + 2,2,4-trimethyl-pentane and its binary sub-systems

Isothermal vapor–liquid equilibrium data determined by the static method at 303.15 K are reported for the binary systems propyl vinyl ether + 1-propanol, 1-propanol + 2,2,4-trimethylpentane and propyl vinyl ether + 2,2,4-trimethylpentane and also for the ternary system propyl vinyl ether + 1-propanol + 2,2,4-trimethyl-pentane. Additionally, new excess volume data are reported for the same systems at 298.15 K. The experimental binary and ternary vapor–liquid equilibrium data were correlated with different G^E models and excess molar volume data were correlated with the Redlich–Kister equation for the binary systems and the Cibulka equation for the ternary system, respectively.     

Isothermal vapor–liquid equilibrium data for the binary mixture difluoromethane (HFC-32) + ethyl fluoride (HFC-161) over a temperature range from 253.15 K to 303.15 K

Isothermal vapor–liquid equilibrium data of difluoromethane (HFC-32) + ethyl fluoride (HFC-161) mixture in the range of temperatures from 253.15 K to 303.15 K have been measured in the wide range of compositions. The experimental method used for this work is the single-cycle type. Using Peng–Robinson (PR) equation of state, combined with the first Modified Huron-Vidal (MHV1) mixing rule and Wilson model, the vapor–liquid equilibrium data are correlated. The correlation results have a good agreement with the experiment results. The average absolute vapor composition deviation is within 0.0125, and its largest absolute deviation of the vapor composition is 0.0568; the average relative pressure deviation is within 0.76% and its largest relative pressure deviation is 2.87%. In addition, the results reveal that there is no azeotrope in the binary system, and their temperature glides are small.