Liquid-liquid phase equilibrium in the system heptane-toluene-mixed extractant triethylene glycol-sulfolane-water

The experimental data on the liquid-liquid equilibrium in the system heptane-toluene-mixed extractant, a 38.4: 57.5: 4.1 wt% triethylene glycol-sulfolane-water mixture, at 50°C were obtained and compared with the data for the same model hydrocarbon system with sulfolane-triethylene glycol-8 wt% water mixture as extractant.     

Liquid-liquid equilibrium and critical phenomena in the water-isopropanol-kerosene-ethyl silicate-40 system

Mutual solubility was studied for the components of pseudoquaternary system water-isopropanolkerosene-ethyl silicate-40, and the compositions of the system in the critical solubility points were determined.     

Liquid-liquid extraction of zinc(II) as its ethyl xanthate

A method for quantitative extraction of zinc with potassium ethyl xanthate into carbon tetrachloride is described. The optimum conditions are: pH 5-6 and Zn(II) to reagent ~1:8 mole ratio. The effects of other ions on the extraction of Zn(2+) have been investigated, and its separation from As(3+), Pb(2+), Cu(2+) and Fe(3+)is described. The possibility of repeated use of the solvent (still loaded with xanthate after the zinc has been stripped) for further extractions (after addition of a little extra xanthate) has been explored. Various stripping agents have been examined, and the optimum conditions found.     

Liquid-liquid equilibrium for the ternary system ethanol/toluene/n-decane: a correction to the existing coexistence curve and NRTL parameters

A correction to the reported liquid–liquid equilibrium parameters using the non-random two liquid (NRTL) thermodynamic model for the ethanol/toluene/n-decane system at 298 K is reported. The parameters were calculated by minimising the residual between the calculated coexistence and the experimental compositions. However, to obtain a physically plausible coexistence curve, a parameter in the NRTL model had to be fixed. This highlights the importance of assessing the entire coexistence curve, as opposed to only comparing the calculated compositions to the experimental data points. This is because undertaking the regression for all the available parameters will result in a smaller residual and better fit of the calculated points to the experimental points. This leads to an apparent improved fit but the complete coexistence curve will show that the parameters are not physically plausible.     

Liquid-liquid extraction: A graphical method for equilibrium stage calculations for quaternary systems

Ruiz Beviá, F., Prats Rico, D. and Marcilla Gomis, A.F., 1984. Liquid-liquid extraction: a graphical method for equilibrium stage calculations for quaternary systems. Fluid Phase Equilibria, 15: 257-265.A very simple graphical method for stage calculations has been developed for quaternary systems. The calculation method is based on the equilibrium representation method proposed by Ruiz and Prats (1983a), and requires only two graphs for solution of the material balances. The method is based completely on experimental data and does not require any simplifying hypotheses.     

Liquid-liquid equilibrium data for ternary systems containing organic acid,hydrocarbon and water

Alessi, P., Kikic, I., Fermeglia, M. and Nonino, C., 1984. Liquid-liquid equilibrium data for ternary systems containing organic acid, hydrocarbon and water. Fluid Phase Equilibria, 18: 93–102.Experimental LLE data are presented for the acetic acid-toluene-water system at 60, 70 and 80°C and for the acetic acid-heptane-water, propionic acid-toluene-water, propionic acid-heptane-water and butanoic acid-toluene-water systems at 50, 60 and 70°C. The data are correlated by means of the NRTL and UNIQUAC models and the relevant parameters are given. The UNIFAC method is used to predict the behavior of the systems.     

Liquid-liquid equilibrium of novel aqueous two-phase systems and evaluation of salting-out abilities of salts

Binodal data are beneficial to the design of aqueous two-phase extraction and the establishment of thermodynamic models. For the 2-propanol + Li₂SO₄/Na₂SO₄/ (NH₄)₂SO₄/K₃PO₄ + water systems and 1-propanol + K₃PO₄/K₃C₆H₅O₇/(NH₄)₃C₆H₅O₇ + water systems, binodal data were determined at 298.15 K. The binodal data were correlated by a theoretical equation on the basis of statistical geometry. The salting-out abilities of salts and the phase-separation abilities of alcohols were evaluated by the effective excluded volume of salt and the binodal curves plotted in molality. A simple Hofmeister series of cations and anions were obtained. The organic salt, K₃C₆H₅O₇, shows as high a salting-out ability as K₃PO₄.      

Liquid-liquid equilibrium data: Their retrieval,correlation and prediction Part I: Retrieval

Part one of this series of articles contains a status report covering the published liquid-liquid equilibrium data for binary and multicomponent mixtures with organic components. Different methods of measuring liquid-liquid equilibrium data are briefly mentioned, and a new, computerized data bank for storage and retrieval of the data is described.This part will be followed by articles on the correlation and prediction of liquid-liquid equilibria.     

Subsolidus phase equilibrium in the Cu-Sb-O system

T6he study of the subsolidus phase equilibrium in Cu-Sb-O system was started using samples with compositions laying, at room temperature, in the CuO-Sb₂O₃ subsystem. Isothermal and non-isothermal experiments were performed to analyze the system in the 500–1000°C range. At high temperatures (over 500°C) the system transforms in a quaternary one: CuO-Cu₂O-Sb₂O₃-Sb₂O₅ as Sb₂O₃ undergoes oxidation to Sb₂O₄ and Sb₂O₅ and Cu₂O₃ reduces to Cu₂O. The formation of the CuSb₂O₆ and Cu₄SbO_4.5 binary compounds is reported. The calculations of mass variation and atomic composition modifications lead to a quaternary oxide representation of the subsolidus phase equilibrium.     

Liquid-vapor equilibrium in the dimethyl sulfoxide-methanol system

The liquid-vapor phase equilibrium in the dimethyl sulfoxide-methanol binary system was studied with the use of a statistical method. Partial pressures of dimethyl sulfoxide and methanol were calculated by integrating the Gibbs-Duhem equation. Molar excess Gibbs energies were described by the Redlich-Kister equation, and correlation parameters were calculated. It was found that molar excess Gibbs energies are negative, and the deviation from ideality increases as temperature increases.     

Solid-liquid equilibrium of the phenanthrene-fluorene system

The solid-liquid equilibrium of the phenanthrene-fluorene system was investigated by differential thermal analysis. Supplementary measurements were applied too: crystal decay temperature examination and melting point examination with a Boetius microscope. The investigated system forms a stable solution with a minimum at 58 mole% of phenanthrene and a temperature of 95.5°.

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Zusammenfassung Das fest-flüssig-Gleichgewicht des Systems Phenantren-Fluoren wurde durch die Differentialthermoanalyse untersucht. Als ergänzende Messungen wurden eingesetzt: die Untersuchung der Kristallzerfallstemperatur und die Prüfung des Schmelzpunktes mit dem Mikroskop nach Boetius. Das untersuchte System bildet eine stabile Lösung mit einem Minimum bei 59 Mol% Phenantren und einer Temperatur von 95.5°C.

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Résumé L'équilibre solide-liquide du système phénanthrène-fluorène a été étudié par analysethermique différentielle. Des essais complémentaires ont également été effectués: détermination de la température de disparition des cristaux et détermination du point de fusion au microscope suivant Boetius. Le système étudié forme une solution stable avec un minimum à 58 mol% de phénanthrène et une température de 95.5°.

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- -. . 5S .% 95.5°.

     

Nitration equilibrium in the meso-erythritol-aqueous nitric acid system

Twelve equilibrium constants have been measured from 16 for sequential-parallel reactions in meso-erythritol nitration to the fully nitrated compound in aqueous HNO₃. Free-energy changes during nitration of the aliphatic polyatomic alcohols, glycerol and meso-erythritol, are highest when diprimary dinitrates (NOON) and (NON) are produced.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2248–2253, October, 1991.     

Study of chemisorption equilibrium in the methanol-silica system

Quantitative IR spectroscopy and desorption mass spectrometry were used to study chemisorption equilibrium in the silica-methanol system. It was determined that the methoxylation of SiO₂ is endothermic. The enthalpy and the equilibrium constant were determined.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 1, pp. 85–87, January–February, 1992.     

水-正已烷-乙醇体系的液液平衡研究

近年来,超临界合成进展迅速。钟炳等人在超临界状态下利用正己烷、环已烷等液体介质,将一氧化碳合成甲醇[1],效率已达90%以上。作为基础工作,刘建国等人研究了水-正己烷-甲醇体系的液液平衡[2];冯耀声等人研究了水-丙烷-乙醇体系的相平衡[3];Letcher等人研究了水-正庚烷-醇体系     

Liquid-liquid extraction procedure exploiting multicommutation in flow system for the determination of molybdenum in plants

A liquid-liquid extraction flow analysis procedure for the spectrophotometric determination of molybdenum in plants at μg l⁻¹ level is described. The flow network comprised a set of solenoid valves assembled to implement the multicommutation approach under microcomputer control. Radiation source (LED, 475 nm), detector (photodiode) and separation chamber were nested together with the flow cell comprising a compact unit. The consumption of reagents (potassium thiocyanate and stannous chloride) and also extracting solvent (isoamyl alcohol) were optimized to 32 mg and 200 μl per determination, respectively. Accuracy was assessed by comparing results with those obtained with ICP-OES and no significant difference at 95% confidence level was observed. Other favorable characteristics such as a linear response ranging from 25 to 150 μg l⁻¹ molybdenum (r=0.999); detection limit of 4.6 μg l⁻¹ sample throughput of 25 determinations per hour and relative standard deviation of 2.5% (n=10) were also achieved.     

Vapor–liquid equilibrium of fatty acid ethyl esters determined using DSC

The vapor–liquid equilibrium data for the systems: ethyl palmitate + ethyl stearate at 5332.9 Pa, ethyl palmitate + ethyl oleate at 5332.9 Pa and 9332.6 Pa and ethyl palmitate + ethyl linoleate at 9332.6 Pa were determined by differential scanning calorimetry (DSC). The esters used in this study are the major components of biodiesel obtained from the transesterification of soybean oil with ethanol. According to the results, DSC is appropriate for determining the vapor–liquid equilibrium of binary systems. The binary interaction parameters of the models Wilson, NRTL and UNIQUAC were fitted to the experimental data obtained in this study.     

Electroconductivity of potassium iodide solutions in the system ethyl alcohol-water

The electrical conduction of potassium iodide solutions in the ethanol-water system in the temperature range 292–323 K was studied using the conductometric method. Specific and molar electrical conductions of the solutions depending on water and potassium iodide contents were determined.     

Vapour-liquid equilibrium in the acetone-water system at 101.325 kPa

Vapour-liquid equilibrium in the title system was measured with special regard to concentration limits. The data of both regions were fitted to six different equations for the determination of the best values of limiting activity coefficients (11.53 and 5.58 for acetone and water, respectively). The densities of solutions at 25°C were determined in both boundary regions.