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41.
Modelling of calcium sulphate solubility in concentrated multi-component sulphate solutions 总被引:1,自引:0,他引:1
The chemistry of several calcium sulphate systems was successfully modelled in multi-component acid-containing sulphate solutions using the mixed solvent electrolyte (MSE) model for calculating the mean activity coefficients of the electrolyte species. The modelling involved the fitting of binary mean activity, heat capacity and solubility data, as well as ternary solubility data. The developed model was shown to accurately predict the solubility of calcium sulphate from 25 to 95 °C in simulated zinc sulphate processing solutions containing MgSO4, MnSO4, Fe2(SO4)3, Na2SO4, (NH4)2SO4 and H2SO4. The addition of H2SO4 results in a significant increase in the calcium sulphate solubility compared to that in water. By increasing the acid concentration, gypsum, which is a metastable phase above 40 °C, dehydrates to anhydrite, and the conversion results in a decrease in the solubility of calcium sulphate. In ZnSO4–H2SO4 solutions, it was found that increasing MgSO4, Na2SO4, Fe2(SO4)3 and (NH4)2SO4 concentrations do not have a pronounced effect on the solubility of calcium sulphate. From a practical perspective, the model is valuable tool for assessing calcium sulphate solubilities over abroad temperature range and for dilute to concentrated multi-component solutions. 相似文献
42.
Attila R. Imre W. Alexander Van Hook Bong Ho Chang Young Chan Bae 《Monatshefte für Chemie / Chemical Monthly》2003,134(12):1529-1539
Summary. Upper critical solution temperatures (UCSTs) for liquid–liquid demixing in a set of mixtures of linear alkanes (pentane (N
1=5) to pentacontane (N
1=50)) with an oligostyrene (1241amu, N
2=12) are reported. We find strong correlation between the Hildebrand solubility parameters of the alkanes and the UCST. Correlations are developed which enable predictions concerning the miscibility of mixtures of compounds with longer chains. 相似文献
43.
Summary. Two main types of binary systems with distinctive solubility behavior under sub- and supercritical conditions were used to
subdivide ternary water-salt systems into three classes. Characteristic features of solubility behavior and phase equilibria
in ternary water-salt systems of each class at temperatures above 200°C are discussed on the basis of available experimental
data and some conclusions obtained as a result of theoretical derivation of fluid and complete phase diagrams.
Corresponding author. E-mail: Valyashko@IGIC.RAS.RU
Received September 25, 2002; accepted (revised) November 28, 2002
Published online April 24, 2003
RID="a"
ID="a" Dedicated to Prof. Dr. H. Gamsjaeger on the occasion of his 70th birthday anniversary 相似文献
44.
H. Lawrence Clever 《Monatshefte für Chemie / Chemical Monthly》2003,134(5):745-750
Summary. There are more than 150 papers that report on the solubility of the four chloromethanes in water. Volume 62 of the Solubility
Data Series compiles and evaluates the papers concerned with the liquid–liquid solubility of the chloromethanes with water.
A similar evaluation has not been carried out for the vapor–liquid solubility at a partial pressure up to the saturation vapor
pressure of the four chloromethanes. This paper uses the liquid–liquid evaluated solubility values to calculate vapor–liquid
Henry’s constants. They are compared with a compilation of Henry’s constants with good agreements between the calculated constants and the median of the compiled constants. It is believed
that the calculated constants are a reliable set of values to use for the vapor–liquid solubility of the chloromethanes in
water.
E-mail: hlclever@worldnet.att.net
Received October 11, 2002; accepted October 22, 2002
Published online April 24, 2003
RID="a"
ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70th birthday 相似文献
45.
The solubility and enthalpy of solution of benzene, cyclohexane, hexane, and heptane in formanide have been determined from titration microcalorimetric experiments at 25°C. The solution enthalpies are significantly more endothermic than in water but still the solubility is much higher. The entropy changes in formamide are small and positive and do not vary significantly with size. The enthalpies of solution of some 1-alkanols, 1-chloro- and 1,5-dichloropentane and pentane-1,5-diol were measured as functions of concentration. The solution enthalpies for 1-alkanols from methanol to decanol increase linearly with chain length. The enthalpic interaction coefficients hxx are small and negative in formamide while they are large and positive in water. The partial molar heat capacities C
p,2
o
for 1-propanol, 1-pentanol, benzene and cyclohexane in formamide were determined at 25°C from drop heat capacity measurements. Values of C
p,2
o
are only slightly larger than the molar heat capacities of the liquid solutes. 相似文献
46.
Paul Ruelle Michel Buchmann Hô Nam-Tran Ulrich W. Kesselring 《Journal of computer-aided molecular design》1992,6(5):431-448
Summary The thermodynamics of mobile order is applied to predict the aqueous solubility of liquid and solid aliphatic and polycyclic aromatic hydrocarbons. The solubility values are mainly determined by the magnitude of the hydrophobic effect. However, contrary to the solubilities of the alkanes, the solubilities of polycyclic aromatic hydrocarbons in water predicted in absence of solute-solvent hydrogen (H) bonds are systematically too low. This shows the contribution of weak specific interactions between the OH groups and the electrons of the aromatic substances. According to the theory, these interactions are characterized by a stability bility constant Ko which can be derived from solubility data. At 25°C, this constant amounts to 80 cm3/mol, the order of magnitude of which can be explained by the competition of these intermolecular bonds with the rather weak self-association bonds in the secondary chains of water. 相似文献
47.
48.
Giuseppina Castronuovo Vittorio Elia Marcella Niccoli Filomena Velleca 《Thermochimica Acta》1998,320(1-2):13-22
The thermodynamics of dissolution in water of a set of substances has been studied calorimetrically. The examined substances were: potassium chloride, (glycyl-glycyl)diketopiperazine, (alanyl-alanyl)diketopiperazine, (leucyl-glycyl)diketopiperazine. They were chosen on the basis of their solubilities, going from a highly soluble electrolyte to the sparingly soluble diketopiperazines. It is shown that, using a commercially available calorimeter, it is possible to perform in a single calorimetric experiment the simultaneous determination of all thermodynamic parameters characterizing dissolution of a substance in a given solvent, i.e. solubility, dissolution enthalpy and dilution enthalpy. The solubility values in water obtained through the proposed method are in good agreement with those reported in the literature and obtained by other techniques. 相似文献
49.
Solubility measurements of 1-butene in water, from 20 to 50°C and at atmospheric pressure, were carried out using a Ben-Naim/Baer-type apparatus. The experimental results have a precision of about ±0.3%. Using accurate thermodynamic relations, the Ostwald coefficients at the experimental conditions and at infinite dilution, the mole fractions of the dissolved gas at the gas partial pressure of 101.325 kPa and the Henry coefficients at the water vapor pressure were calculated. The mole fraction of dissolved gas were fitted to the Clarke, Glew, and Weiss equation and thermodynamic quantities, standard molar Gibbs energy, entropy, and enthalpy changes, for the process of transferring the 1-butene molecules from the gaseous to the water phase, were computed. Moreover, solubility measurements of 1-butene in an aqueous medium for the cultivation of Xanthobacter Py2 in the same temperature range were also performed at atmospheric pressure. These solubility data are approximately 2.6% lower than those observed in pure water. 相似文献
50.
Magdalena Kurdziel Elżbieta Szczepaniec-Cieciak Monika Watorczyk Barbara Dabrowska 《Journal of solution chemistry》2004,33(5):453-464
The solubility of solid 2-methyl-1,3-butadiene (isoprene) in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K has been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in the solute. The experimental value of the mole fraction solubility of solid isoprene in liquid argon at 87.3 K is (1.41 ± 0.27) × 10–6 and (1.56 ± 0.36) × 10–7 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l
12 were also calculated. At 90.0 K liquid argon is a better solvent for isoprene than is liquid nitrogen. The experimental values of the solubilities of isoprene in liquid argon and nitrogen were compared with results obtained for selected unsaturated and aromatic hydrocarbons. 相似文献