Novel experimental liquid−liquid equilibrium measurements were performed for three ternary systems containing γ-valerolactone + n-tetradecane + (butanoic acid or hexanoic acid or methyl myristate) at T = 298.15 K. The quantification of the coexisting phases was performed using an indirect method which relies on the variation of physical properties (density) along the binodal curve. The experimental data were successfully correlated by the nonrandom two-liquid and the universal quasichemical models.

Although petroleum is widely used to make solvents and to produce energy, solvents derived from it, such as acetonitrile, may not be the safest and most sustainable options currently available. Additionally, processes such as the Fischer–Tropsch synthesis emerge as an intelligent alternative to produce energy from coal, biomass, or natural gas to supply the increasing demand for petroleum-derived products. Thus, with a green solvent, γ-valerolactone, applied to the removal of oxygenated compounds from a Fischer–Tropsch process stream, this work suggests the application of a less toxic solvent to an alternative energy production process through model systems. In this sense, liquid–liquid equilibrium experimental data were measured for systems composed of an oxygenated solute (1-heptanol, propanone, 2-butanone, or 2-heptanone) + γ-valerolactone + n-tetradecane at 298.15 K. The liquid–liquid equilibrium data were successfully correlated by the nonrandom two-liquid model with a medium average deviation lower than 1%. Therefore, the measured experimental data may contribute to the design of a liquid–liquid extraction process applied to the refinement of synthetic crude oil from a Fischer–Tropsch synthesis.

A compilation of available experimental data for acetone-water mixtures with the reciprocal salt system Na+, K+ || Cl−, SO42− is presented. Significant inconsistencies among experimental data are pointed out. New freezing point measurements are reported for the binary acetone-water system at 12 different compositions. UNIQUAC parameters are determined on the basis of the available data from literature. Modeling results are presented. Vapor-liquid, liquid-liquid, and solid-liquid equilibria together with thermal properties are reproduced well by the model using only 14 parameters. The major drawback of the model is that the calculated liquid-liquid equilibrium regions of systems with KCl and NaCl are larger than the experimentally determined regions. The model is valid in the temperature range from −16 to 100 °C.

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Isothermal vapor−liquid equilibrium measurements were performed for aqueous solutions containing N-methyl diethanolamine (MDEA), MDEA + ammonia (NH 3 ), MDEA + potassium hydroxide (KOH), MDEA + carbon dioxide (CO 2 ), NH 3 + CO 2 , and MDEA + NH 3 + CO 2 . The experiments were carried out between 310 and 390 K and 0.07 and 34 bar using a static synthetic apparatus. Overall, 202 data points are reported in terms of total volume, total number of moles, temperature, and pressure. The experimental results for MDEA(aq), NH 3 (aq) + CO 2 (aq), and MDEA(aq) + CO 2 (aq) are in good agreement with the calculations done using the Extended UNIQUAC model within the studied range. The data presented in this work are also comparable to previously published measurements. This work reports for the first time VLE measurements for aqueous mixtures of MDEA + NH 3 and MDEA + KOH. These data suggest that the interactions between MDEA(aq) and NH 3 (aq) or K + (aq) ions have a minor effect on the equilibrium pressures. Consequently, other physical properties are needed to describe the thermodynamic state of these systems, such as heat capacity, heat of dilution, and other phase equilibrium measurements. The isothermal VLE measurements for solutions containing NH 3 (aq) showed a pressure minimum that was confirmed by model estimates and by other works done in similar conditions. As a consequence, it is not possible to estimate the partial pressure of CO 2 based on the difference between the pressure at equilibrium conditions and the partial pressure of the lean solvent. This paper demonstrates that this common approach to determining the partial pressure of gases may introduce a bias in these values. The dissolution of CO 2 into MDEA(aq) + NH 3 (aq) mixtures changes the speciation of the system, leading to an increase in the concentration of their protonated species (MDEAH + (aq) and NH 4 + (aq), respectively). For this reason, the interaction between these charged species must be determined in order to perform reliable phase equilibrium calculations. Ultimately, the measurements reported in this work can be used for thermodynamic modeling of CO 2 capture solvents to ensure accurate results in process simulation.

Solid−liquid equilibrium (SLE) data were obtained at 0.1 MPa for binary, ternary, and quaternary aqueous solutions containing ammonia (NH 3 ), ammonium bicarbonate (NH 4 HCO 3 ), methyl diethanolamine (MDEA), and potassium carbonate (K 2 CO 3 ) using a modified Beckmann apparatus. The reproducibility of the experimental method was verified by measuring the SLE of aqueous solutions containing NH 3 , K 2 CO 3 , or MDEA in a temperature range between 237 and 273 K. A total of 120 new data points were measured for MDEA−NH 3 and NH 4 HCO 3 −H 2 O mixtures (250 to 305 K), and 23 new data points were obtained for MDEA−K 2 CO 3 −H 2 O solutions (250 to 270 K). These measurements allow for an accurate estimation of water activity in such mixtures and provide insights on the limits of solid formation. The results indicate that the addition of MDEA increases the solubility of NH 4 HCO 3 , whereas a liquid−liquid split was observed when K 2 CO 3 was added to aqueous MDEA. This opens the possibility of using it as a phase demixing solvent for carbon capture. Despite the extensive literature regarding mixed salt−amine solutions, liquid demixing in such systems has not been reported before. For this reason, the binodal curve for the MDEA−K 2 CO 3 −H 2 O solution was measured at 293.15 K using the method of cloud point titration. These results assist the selection of operation parameters that avoid a liquid−liquid split in the process.

There are few measurements of barium sulfate (BaSO4) solubility in water above 373 K available in the literature. BaSO4 solubility data at water saturation pressure are scare. The pressure dependence on BaSO4 solubility has not previously been comprehensively reported for the pressure range 100–350 bar. In this work, an experimental apparatus was designed and built to measure BaSO4 solubility in aqueous solutions under high-pressure (HP), high-temperature (HT) conditions. The solubility of BaSO4 was experimentally determined in pure water over the temperature range from T = (323.1 to 440.1) K and pressures ranging from p = (1 to 350) bar. Most of the measurements were done at water saturation pressure: six data points were done above the saturation pressure (323.1–373.1 K) and 10 experiments were conducted at water saturation (373.1–440.1 K). The reliability of the extended UNIQUAC model and results generated in this work was demonstrated by comparing with the scrutinized experimental data reported in the literature. The model gives a very good agreement with BaSO4 equilibrium solubility data, demonstrating the reliability of the extended UNIQUAC model. The accuracy of the model at high temperature and saturated pressure due to data insufficiencies is discussed.