Vapour pressure data of ε-caprolactone, δ-hexalactone,and γ-caprolactone

This work reports new vapour pressure data of ε-caprolactone, δ-hexalactone, and γ-caprolactone. Vapour pressure measurements were carried out over the temperature range of (283 to 343) K using the static method with a differential pressure transducer. Degassing was performed inside the equilibrium cell by freezing and thawing the samples under moderate vacuum (about 50 kPa). For ε-caprolactone and δ-hexalactone vapour pressure values varied in the range of (0.045 to 0.769) kPa and (0.005 to 0.354) kPa, respectively, while for γ-caprolactone a maximum value of 1.367 kPa was found. Experimental vapour pressure data were correlated by the Antoine equation with a good agreement between experiment and model.     

Saturated liquid densities of propane at T = (280 to 365) K

Saturated liquid densities for propane were obtained by means of a metal-bellows variable volumometer at T = (280, 300, 320, 340, 360, and 365) K. The mol-fraction purity of the propane used in the measurements was 0.99997. The expanded uncertainties (k = 2) in temperature, pressure, and density measurements were estimated to be less than ±3 mK, 1.4 kPa (p ≦ 7 MPa), and ±0.09%, respectively. For the determination of the saturation boundary at each temperature for propane, we measured the density data at intervals of about 20 kPa very close to the saturation boundary. After such measurements had been completed, the saturated liquid density data at each temperature were determined as the intersection between the isotherm and our previously determined vapour pressure value. The discrepancies between the three series in the present measurements, in which different sample fillings were used, were also confirmed to be sufficiently lower than the experimental uncertainty. The saturated liquid density correlation was also provided for the systematic comparisons between the present measurements and the literature data.     

Isothermal (vapour + liquid) equilibrium at several temperatures of (1-chlorobutane + 1-butanol,or 2-methyl-2-propanol)

Vapour pressures of (1-chlorobutane  +  1-butanol, or 2-methyl-2-propanol) at several temperatures between T =  278.15 and T =  323.15 K were measured by a static method. Reduction of the vapour pressures to obtain activity coefficients and excess molar Gibbs energies was carried out by fitting the vapour pressure data to the Redlich–Kister equation according to Barker’s method. For (1-chlorobutane  +  2-methyl-2-propanol) azeotropic mixtures with a minimum boiling temperature were observed over the whole temperature range.     

Water activities of ternary mixtures of poly(ethylene glycol), NaCl and water over the temperature range of 293.15 K to 313.15 K

The improved isopiestic method has been used to obtain activities of water for aqueous solutions of poly(ethylene glycol) 400/NaCl at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K. From these measurements, values of the vapour pressure of solutions were determined. The effect of temperature on the (vapour + liquid) equilibrium of {poly(ethylene glycol) + NaCl + H₂O} systems has been studied. It was found that the slope of the constant activity lines for water increased with increasing temperature. The results have been discussed on the basis of the effect of temperature on the hydrophobicity of the polymer. Also it was found that the vapour pressure depression for an aqueous (PEG + NaCl) system is more than the sum of those for the corresponding binary solutions. Furthermore, the segment-based local composition Wilson model has been used for the correlation of the experimental water activity data. The agreement between the correlation and the experimental data are good.     

New Knudsen effusion apparatus with simultaneous gravimetric and quartz crystal microbalance mass loss detection

A new Knudsen effusion apparatus, enabling simultaneous gravimetric and quartz crystal microbalance mass loss detection, is described. This device allows the measurement of vapour pressures of small sample mass (50 to 100) mg over a wide temperature range (350 to 650) K using very short effusion time intervals. The performance of the apparatus was checked by measuring the vapour pressures of anthracene, benzanthrone, and 1,3,5-triphenylbenzene, between (0.1 and 1) Pa, over temperature intervals of 20 K. The derived standard molar enthalpies of sublimation and vapour pressures are in excellent agreement with the mean of the available literature values and with the recommended values. The new working methodology and design of this apparatus allows the measurement of high quality vapour pressure data due to: accurate temperature measurement and control; improvement in vacuum thermal contact between the effusion cell and the oven metal block; optimisation of the quartz crystal sensor head microbalance position; efficient temperature control of the quartz crystal microbalance head; accurate measurement of the resonance crystal frequency using an impedance circuit analyser methodology.     

Measurements of vapour pressures and saturated-liquid densities for n-butane at T = (280 to 424) K

Fifteen measurements of the vapour pressure and seven measurements of the saturated-liquid density for n-butane were obtained by means of a metal-bellows variable volumometer at T = (280 to 424) K. The mole fraction purity of the n-butane used in the measurements was 0.9997. The expanded uncertainties (k = 2) in temperature, pressure, and density measurements have been estimated to be less than 3 mK, less than 0.8 kPa, and 0.08%, respectively. Throughout the present measurements for n-butane, the vapour-pressure value and saturated-liquid density value at each temperature were determined as average value of the pressures on various volume of the bellows at the same temperature, and as the point of intersection between the isotherm and our vapour-pressure value, respectively. The expanded uncertainties (k = 2) in the present vapour-pressure data and saturated-liquid density data have also been estimated to be less than 1.1 kPa and 0.08%, respectively, except the uncertainty of the saturated-liquid density data at T = 424 K being 0.29% (0.83 kg · m⁻³). Based on the present measurements as input data, the Wagner-type vapour-pressure correlation and the saturated-liquid density correlation were also provided for the systematic comparisons between the present measurements and the literature data.     

Vapour pressures of n-pentane determined by comparative ebulliometry

The vapour pressures of n-pentane have been measured using comparative ebulliometry with water as the reference substance. The measurements cover the temperature and pressure ranges 309 K and 102 kPa to 456 K and 2728 kPa. When combined with selected literature results, the range was extended downwards to a temperature and pressure of 268.8 K and 19.9 kPa and the combined data sets were correlated by a Wagner-type equation with a standard deviation of 18 Pa in the vapour pressure. The critical pressure was treated as an adjustable parameter and the value p_c = 3367.4 kPa was obtained using a selected critical temperature, T_c = 469.7 K. The calculated normal boiling temperature was T_b = 309.207 K and an extrapolation to the triple point temperature T_tp = 143.48 K predicted a pressure of p_tp = 0.078 Pa.     

Dichloromethane: Revision and extension of pρT relationships for the liquid

In spite of the great importance of the PVT data of dichloromethane, only limited information on these data seems to be available in the literature. In this work, we present experimental densities of the liquid dichloromethane over the ranges T = (270 to 330) K and p = (0.1 to 30) MPa using a vibrating tube densimeter, model DMA 512P from Anton Paar with an estimated uncertainty lower than ±0.5 kg · m^?3. The high consistency of our data compared with those measured by other authors allows that all the experimental results have been combined and correlated together with the Tait equation in the temperature and pressure ranges T = (244 to 430) K and p = (0.1 to 101) MPa. From the Tait equation, thermomechanical coefficients as the isothermal compressibility, isobaric expansivity, thermal pressure, and internal pressure were calculated. Some of the measurements of density were made at pressures lower than the critical pressure which enabled us to obtain very reliable values for the density of the saturated liquid within the range T = (270.0 to 330.0) K. These data were combined with other values existing in the literature, which made it possible to extend the information on the saturated liquid density to the range T = (208 to 399) K. From these data, a new equation describing the saturated liquid density of dichloromethane was found covering the entire temperature range between the triple and the critical temperatures. A new equation for the vapour pressure was found by using selected values from the literature covering the entire temperature range between the triple and the critical temperatures.     

Vapour pressures,densities, and viscosities of the (water + lithium bromide + potassium acetate) system and (water + lithium bromide + sodium lactate) system

Measurements of thermophysical properties (vapour pressure, density, and viscosity) of the (water + lithium bromide + potassium acetate) system LiBr:CH₃COOK = 2:1 by mass ratio and the (water + lithium bromide + sodium lactate) system LiBr:CH₃CH(OH)COONa = 2:1 by mass ratio were measured. The system, a possible new working fluid for absorption heat pump, consists of absorbent (LiBr + CH₃COOK) or (LiBr + CH₃CH(OH)COONa) and refrigerant H₂O. The vapour pressures were measured in the ranges of temperature and absorbent concentration from T = (293.15 to 333.15) K and from mass fraction 0.20 to 0.50, densities and viscosities were measured from T = (293.15 to 323.15) K and from mass fraction 0.20 to 0.40. The experimental data were correlated with an Antoine-type equation. Densities and viscosities were measured in the same range of temperature and absorbent concentration as that of the vapour pressure. Regression equations for densities and viscosities were obtained with a minimum mean square error criterion.     

Partial molar volumes of organic solutes in water. XVI. Selected aliphatic hydroxyderivatives(aq) at T =(298 to 573) K and at pressures up to 30 MPa

Density data for dilute aqueous solutions of two diols (1,6-hexanediol, 2,2-dimethyl-1,3-propanediol) and two polyhydric alcohols (2,2-bis(hydroxymethyl)-1,3-propanediol, 1,2,3,4,5-pentanepentaol) are presented together with partial molar volumes at infinite dilution calculated from the experimental data. The measurements were performed at temperatures from T = 298 K up to T = 573 K and at pressure close to the saturated vapour pressure of water, at pressures between 15 and 20 MPa and at p = 30 MPa. While temperature dependences of partial molar volumes of both diols are monotonous, maxima are observed on the curves for polyhydric alcohols. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter.     

Vapour pressure of diethyl phthalate

Measurements of vapour pressure in the liquid phase and of enthalpy of vaporisation and results of calculation of ideal-gas properties for diethyl phthalate are reported. The method of comparative ebulliometry, the static method, and the Knudsen mass-loss effusion method were employed to determine the vapour pressure. A Calvet-type differential microcalorimeter was used to measure the enthalpy of vaporisation. Simultaneous correlation of vapour pressure, of enthalpy of vaporisation and of difference in heat capacities of ideal gas and liquid/solid phases was used to generate parameters of the Cox equation that cover both the (vapour + solid) equilibrium (approximate temperature range from 220 K to 270 K) and (vapour + liquid) equilibrium (from 270 K to 520 K). Vapour pressure and enthalpy of vaporisation derived from the fit are reported at the triple-point temperature T = 269.92 K (p = 0.0029 Pa, Δ_vapH_m = 85.10 kJ · mol⁻¹ ), at T = 298.15 K (p = 0.099 Pa, Δ_vapH_m = 82.09 kJ · mol⁻¹), and at the normal boiling temperature T = 570.50 K (Δ_vapH_m = 56.49 kJ · mol⁻¹). Measured vapour pressures and measured and calculated enthalpies of vaporisation are compared with literature data.     

Vapour pressures of n-hexane determined by comparative ebulliometry

The vapour pressures of n-hexane have been measured using comparative ebulliometry with water as the reference fluid. The measurements cover the temperature and pressure range (315.7 K, 41.1 kPa) to (504.0 K, 2876.8 kPa) and join smoothly with results selected from the literature to provide consistent results down to (289.7 K, 13.8 kPa). The combined data set have been described by a Wagner style equation with a fractional standard deviation of 4.2 · 10⁻⁵ in the vapour pressure. The critical pressure p_c was treated as an adjustable parameter and the value of p_c = 3027 kPa was calculated from the smoothing equation using a selected critical temperature of T_c = 507.49 K. The calculated normal boiling temperature is T_b = 341.866 K and an extrapolation to the triple-point temperature T_tp = 177.87 K predicts a triple-point pressure of p_tp = 1.23 Pa.     

Vapour pressures,densities, and viscosities of the aqueous solutions containing (triethylene glycol or propylene glycol) and (LiCl or LiBr)

In this work, new results for density, viscosity, and vapour pressure of (triethylene glycol or propylene glycol) in H₂O with LiCl or LiBr systems over temperatures ranging from 303.15 K to 343.15 K are presented. For each ternary system, four systems of which (4 to 25) mass% salt mixed with various glycols (50 to 80) mass% were studied. Incorporated with the pseudo-solvent approach, a vapour pressure model based on the mean spherical approximation for aqueous electrolyte solutions was used to represent the measured vapour pressure of the investigated systems. The present density and viscosity results were also correlated as a function of temperature and composition. The correlations yield satisfactory results. Compared to the conventionally used liquid desiccants, the vapour pressures of the systems studied yield smaller values of vapour pressures. The properties presented in this work are, in general, of sufficient accuracy for most engineering-design calculations.     

(Vapour + liquid) equilibrium data for the binary system of {trifluoroiodomethane (R13I1) + trans-1, 3, 3, 3-tetrafluoropropene (R1234ze (E))} at various temperatures from (258.150 to 298.150) K

(Vapour + liquid) equilibrium (VLE) data for the binary system of {trifluoroiodomethane (R13I1) + trans-1, 3, 3, 3-tetrafluoropropene (R1234ze (E))} were measured by a static-analytic method within the temperature range of (258.150 to 298.150) K. The experimental data were correlated using the Peng–Robinson equation of state (PR EoS) with the Huron–Vidal (HV) mixing rule involving the NRTL activity coefficient model. The results show good agreement with experimental values for the binary system at each temperature point. The maximum average absolute relative deviation of pressure is 0.28%, while the maximum average absolute deviation of vapour phase mole fraction is 0.0025. Obviously azeotropic behaviour can be found for the measured temperature range here.     

Vapour pressures of selected organic compounds down to 1 mPa,using mass-loss Knudsen effusion method

A recently developed Knudsen effusion apparatus was improved and used for measurements of vapour pressures of selected organic compounds. Calorimetric studies were conducted using a Calvet-type calorimeter, complementing the information obtained for the vapour pressures and facilitating the modelling and analysis of the data.Vapour pressures of benzoic acid, a reference substance, were determined at temperatures between 269 K and 317 K, corresponding to a pressure range from 2 mPa to 1 Pa, extending the range of results available in the literature to lower pressures. Benzanthrone was studied between temperatures 360 K and 410 K (5 mPa–1 Pa) in order to test the apparatus at higher temperatures.Values presented in the literature for the vapour pressure of solid n-octadecane, one of the most promising compounds to be used as “phase change material” for textile applications, were found inconsistent with the triple point of the substance. Sublimation pressures were measured for this compound between T = 286 K and 298 K (2–20 mPa) allowing the correction of the existing values. Finally, vapour pressures of diphenyl carbonate, a compound of high industrial relevance for its use in the production of polycarbonates, were determined from T = 302 K to 332 K (0.02–1 Pa).     

A mass spectrometric investigation of the vaporisation behaviour in the (U + Pu + O) system

The vaporisation behaviour of (U, Pu)O₂ mixed oxides (Pu/M = 0.25, 0.50 and 0.75, with M = U + Pu) was studied by means of mass spectrometry. Hyperstoichiometric samples were heated in a Knudsen cell up to T = 2300 K. The evolution of the uranium and plutonium bearing gaseous species was studied as a function of time in order to evaluate the congruent vapour composition. Ionisation efficiency measurements were performed and the partial pressures of the gaseous species involved in the vaporisation process were determined. The vapour pressure has also been calculated using a thermochemical model for the (U + Pu + O) system. A quasi congruent composition with respect to the O/M ratio has been assumed, in agreement with the experiments. Nevertheless, the evaluation of all the experimental and calculated results shows that a total congruent composition exists for a single composition of the mixed oxide (MOX) samples with a Pu/M content slightly lower than 0.50. A good agreement is obtained between the calculated and experimental vapour pressure data, as well as the quasi congruent vaporisation compositions.     

Thermodynamic properties and equation of state of liquid di-isodecyl phthalate at temperature between (273 and 423) K and at pressures up to 140 MPa

We report measurements of the thermodynamic properties of liquid di-isodecyl phthalate (DIDP) and an equation of state determined therefrom. The speed of sound in DIDP was measured at temperatures between (293.15 and 413.15) K and a pressures between (0.1 and 140) MPa with a relative uncertainty of 0.1%. In addition, the isobaric specific heat capacity was measured at temperatures between (293.15 and 423.15) K at a pressure of 0.1 MPa with a relative uncertainty of 1%, and the density was measured at temperatures between (273.15 and 413.15) K at a pressure of 0.1 MPa with a relative uncertainty of 0.015%. The thermodynamic properties of DIDP were obtained from the measured speeds of sound by thermodynamic integration starting from the initial values of density and isobaric specific heat capacity obtained experimentally. The results have been represented by a new equation of state containing nine parameters with an uncertainty in density not worse than 0.025%. Comparisons with literature data are made.     

Liquid–liquid equilibrium data of water with neohexane,methylcyclohexane, tert-butyl methyl ether,n-heptane and vapor–liquid–liquid equilibrium with methane

Liquid–liquid equilibrium (LLE) data for non-aqueous liquid (neohexane [NH], tert-butyl methyl ether [TBME], methylcyclohexane [MCH], or n-heptane [nC₇]) and water have been measured under atmospheric pressure at 275.5, 283.15, and 298.15 K. It was found that TBME is the most water soluble followed by NH, MCH, and nC₇. As the temperature increased, the solubility of the non-aqueous liquids (NALs) in water decreased. The solubility of water in the non-aqueous liquid was found to increase in the following order: MCH < nC₇ < NH < TBME. It was found to increase with increasing temperature. In addition, vapour–liquid–liquid equilibrium (VLLE) data for the above binary systems with methane were measured at 275.5 K and at 120, 1000, and 2000 kPa. It was found that the vapour composition of water and NALs decreased as the pressure increased. The water content in the non-aqueous phase was not a strong function of pressure. The concentration of methane in the non-aqueous phase increased as the pressure increased. Furthermore, the concentration of the methane and NALs in the water phase increased proportionally with pressure. The solubility of methane in water followed Henry's law. It is noted that the measurements were completed prior to the onset of hydrate nucleation.     

Vapour pressure measurement for binary and ternary systems containing water methanol ethanol and an ionic liquid 1-ethyl-3-ethylimidazolium diethylphosphate

Vapour pressure data were measured for three binary systems containing water, methanol or ethanol with an ionic liquid (IL) 1-ethyl-3-ethylimidazolium diethylphosphate([EEIM][DEP]) and for three ternary systems, i.e. (water + ethanol + [EEIM][DEP]), (water  + methanol + [EEIM][DEP]), and (ethanol + methanol + [EEIM][DEP]), at varying temperature and IL-content ranging from mass fraction of 0.10 to 0.85 by a quasi-static method. The vapour pressure data of the binary systems were correlated by NRTL equation with average absolute relative deviation (ARD) within 0.0091. The binary NRTL parameters were used to predict the vapour pressure of the ternary systems (ethanol + water + [EEIM][DEP]), (water + methanol + [EEIM][DEP]), and (ethanol +  methanol + [EEIM][DEP]) with an overall ARD of 0.037 and the maximum deviation of −0.1295. The results indicate that ionic liquid [EEIM][DEP] can give rise to a negative deviation from the Raoult’s law for the solvents of water, methanol and ethanol, but to a varying degree leading to the variation of relative volatility of a solvent and even removal of azeotrope for (water + ethanol).     

Measurements of (p, ρ, T) properties for isobutane in the temperature range from 280 K to 440 K at pressures up to 200 MPa

Measurements of (p, ρ, T) properties for isobutane in the compressed liquid phase have been obtained by means of a metal-bellows variable volumometer in the temperature range from 280 K to 440 K at pressures up to 200 MPa. The volume-fraction purity of isobutane used was 0.9999. The expanded uncertainties (k = 2) of temperature, pressure, and density measurements have been estimated to be less than 3 mK, 1.5 kPa (p ⩽ 7 MPa), 0.06% (7 MPa < p ⩽ 50 MPa), 0.1% (50 MPa < p ⩽ 150 MPa), and 0.2% (p > 150 MPa), and 0.11%, respectively. In region more than 100 MPa at 280 K and 440 K, the uncertainty in density measurements rise up to 0.15% and 0.23%, respectively. The differences of the present density values at the same temperature between two series of measurements, in which the sample fillings are different, are within the maximum deviation of 0.09% in density, which is enough lower than the expanded uncertainty in density. Eight (p, ρ, T) measurements at the same temperatures and pressures as the literature values have been conducted for comparison. In addition, vapour pressures were measured at T = (280, 300) K. Moreover, the comparisons of the available equations of state with the present measurements are reported.