Diffusion coefficients of nickel chloride in aqueous solutions of lactose at T = 298.15 K and T = 310.15 K

Binary mutual diffusion coefficients (interdiffusion coefficients) of nickel chloride in water at T = 298.15 K and T = 310.15 K, and at concentrations between (0.000 and 0.100) mol · dm^?3, using a Taylor dispersion method have been measured. These data are discussed on the basis of the Onsager–Fuoss and Pikal models. The equivalent conductance at infinitesimal concentration of the nickel ion in these solutions at T = 310.15 K has been estimated using these results. Through the same technique, ternary mutual diffusion coefficients (D₁₁, D₂₂, D₁₂, and D₂₁) for aqueous solutions containing NiCl₂ and lactose, at T = 298.15 K and T = 310.15 K, and at different carrier concentrations were also measured. These data permit us to have a better understanding of the structure of these systems and the thermodynamic behaviour of NiCl₂ in different media.     

Diffusion of sodium alginate in aqueous solutions at T = 298.15 K

Taylor dispersion technique was used for measuring mutual diffusion coefficients of sodium alginate aqueous solutions at T = 298.15 K, by using as carrier stream solution both pure water and solutions of this polyelectrolyte at a slightly different concentration. The limiting values found at infinitesimal ionic strength, D⁰, were determined by extrapolating to c → 0. These studies were complemented by molecular mechanics calculations. From the experimental data, it was possible to estimate both the limiting conductivity and the tracer diffusion coefficient values for the alginate anion, and the hydrodynamic radius of the sodium alginate (NaC₆H₇O₆), as well as to discuss the influence of the kinetic, thermodynamic and viscosity factors on the diffusion of sodium alginate in aqueous solutions at finite concentrations. Thus, the aim of our innovative research is to contribute to a better understanding of the structure and the thermodynamic behavior of these polymeric systems in solution and supplying the scientific and technological communities with data on these important parameters in solution transport processes.     

Viscosity measurements for squalane at high pressures to 350 MPa from T = (293.15 to 363.15) K

Squalane is being recommended as a secondary reference material for viscometry at moderate to high pressure and at moderate viscosity. As part of this work, a correlation has been developed for atmospheric pressure (Comuñas et al., 2013) [12]. Here we report new experimental high pressure viscosities for squalane (176 data points obtained for temperatures (293.15 to 363.15) K, at pressures up to 350 MPa with a maximum viscosity of 745 mPa · s). These have been determined with four different falling-body viscometers as well as a quartz crystal resonator viscometer. A preliminary high pressure viscosity correlation for squalane is proposed, based on our new data. At pressures up to 350 MPa, this correlation provides an absolute average deviation of 1.5% with a maximum absolute deviation of 8.9%. Comparison is made between the different instruments. In addition, we have also considered the validity of a thermodynamic scaling model.     

Liquid density of HFE-7200 and HFE-7500 from T = (283 to 363) K at pressures up to 100 MPa

The liquid densities of HFE-7200 (1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane, CAS Registry Number: 163702-05-4) and HFE-7500 (3-ethoxyperfluoro(2-methylhexane), CAS Registry Number: 297730-93-9) have been measured over the temperature range from (283 to 363) K and pressures up to 100 MPa by using a high pressure vibrating-tube densimeter. R134a has been used as a reference fluid to validate the densimeter. The uncertainty of each obtained datum was estimated, and the maximum expanded uncertainty with a level of confidence of 0.95 (k = 2) of density measurement for HFE-7200 and HFE-7500 were 0.04% and 0.03%, respectively. The measured liquid densities were correlated with the modified Tait equation and the maximum deviation is less than 0.03%. The isothermal compressibility and isobaric thermal expansivity were also calculated.     

Enthalpic interactions of N-glycylglycine with xylitol in aqueous sodium chloride and potassium chloride solutions at T = 298.15 K

The mixing enthalpies of N-glycylglycine with xylitol and their respective enthalpies of dilution in aqueous sodium chloride and potassium chloride solutions have been determined by using flow-mix isothermal microcalorimetry at the temperature of 298.15 K. These experimental results have been used to determine the heterotactic enthalpic interaction coefficients (h_xy, h_xxy, and h_xyy) according to the McMillan–Mayer theory. It has been found that the heterotactic enthalpic pairwise interaction coefficients h_xy between N-glycylglycine and xylitol in aqueous sodium chloride and potassium chloride solutions are negative and become less negative with an increase in the molality of sodium chloride or potassium chloride. The results are discussed in terms of solute–solute and solute–solvent interactions.     

Effect of potassium chloride on diffusion of theophylline at T = 298.15 K

Ternary mutual diffusion coefficients measured by Taylor dispersion method (D₁₁, D₂₂, D₁₂, and D₂₁) are reported for aqueous solutions of KCl + theophylline (THP) at T = 298.15 K at carrier concentrations from (0.000 to 0.010) mol · dm^?3, for each solute. These diffusion coefficients have been measured having in mind a better understanding of the structure of these systems and the thermodynamic behavior of potassium chloride and theophylline in solution. For example, from these data it will be possible to make conclusions about the influence of this electrolyte in diffusion of THP and to estimate some parameters, such as the diffusion coefficient of the aggregate between KCl and THP.     

Density and activity of pertechnetic acid aqueous solutions at T = 298.15 K

The previous isopiestic investigations of HTcO₄ aqueous solutions at T = 298.15 K are believed to be unreliable, because of the formation of a ternary mixture at high molality. Consequently, published isopiestic molalities for aqueous HTcO₄ solutions at T = 298.15 K were completed and corrected. Binary data (variation of the osmotic coefficient and activity coefficient of the electrolyte in solution in the water) at T = 298.15 K for pertechnetic acid HTcO₄ were determined by direct water activity measurements. These measurements extend from molality m = 1.4 mol · kg⁻¹ to m = 8.32 mol · kg⁻¹. The variation of the osmotic coefficient of this acid in water is represented mathematically. Density variations at T = 298.15 K are also established and used to express the activity coefficient values on both the molar and molal concentration scale. The density law leads to the partial molar volume variations for aqueous HTcO₄ solutions at T = 298.15 K, which are compared with published data.     

Viscometric studies on saccharides in aqueous magnesium chloride solutions at T = (288.15 to 318.15) K

The viscosity B-coefficients of mono-, di-, tri-saccharides and the derivatives (methyl glycosides) in m_B = (0.5, 1.0, 2.0, and 3.0) mol · kg⁻¹ aqueous solutions of magnesium chloride have been determined from viscosity data using the Jones–Dole equation at T = (288.15, 298.15, 308.15, and 318.15) K. The viscosity B-coefficients of transfer (Δ_tB), the temperature derivatives of B-coefficients (dB/dT), pair and triplet viscometric interaction coefficients (η_AB, η_ABB) have been determined. The viscosity B-coefficients data of systems studied in water have been reported earlier. The results have been interpreted in light of the solute–solute and solute–solvent interactions occurring in these systems. The comparison of results has been made with those reported in the presence of potassium chloride, ammonium sulphate, and sodium sulphate.     

Heat of solution of polyhalite and its analogues at T = 298.15 K

Calorimetric measurements have been performed to determine the heat of dissolution of polyhalite K₂SO₄ · MgSO₄ · 2CaSO₄ · 2H₂O and its analogues K₂SO₄ · MSO₄ · 2CaSO₄ · 2H₂O (M = Mn, Co, Ni, Cu, and Zn) at T = 298.15 K. The dissolution experiments were carried out in NaClO₄ solution with varying concentrations (0.5 to 2.0) mol kg^?1. All polyhalites dissolve exothermically. Exothermicity increases with concentration of NaClO₄. An extrapolation to infinite dilution was done using the SIT model.Within the limits of experimental uncertainty, the enthalpies of dissolution for the triple salts K₂MgCa₂(SO₄)₄ · 2H₂O with M = Mg, Mn, Ni, and Zn coincide. The value for the cobalt salt is noticeably less exothermic. Dissolution enthalpy of leightonite K₂CuCa₂(SO₄)₄ · 2H₂O, which does not crystallize in the polyhalite structure, deviates considerably within the series.     

Excess properties of the binary mixtures of methylcyclohexane + alkanes (C6 to C12) at T = 298.15 K to T = 308.15 K

Experimental values of density, viscosity, and refractive index at T = (298.15, 303.15, and 308.15) K while the speed of sound at T = 298.15 K in the binary mixtures of methylcyclohexane with n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-dodecane, and iso-octane are presented over the entire mole fraction range of the binary mixtures. Using these data, excess molar volume, deviations in viscosity, molar refraction, speed of sound, and isentropic compressibility are calculated. All the computed quantities are fitted to Redlich and Kister equation to derive the coefficients and estimate the standard error values. Such a study on model calculations in addition to presentation of experimental data on binary mixtures are useful to understand the mixing behaviour of liquids in terms of molecular interactions and orientational order–disorder effects.     

The dilution enthalpies of l-prolinol in N,N-dimethylformamide aqueous solutions at T = 298.15 K

Values of the enthalpy of dilution were measured for l-prolinol in pure water and N,N-dimethylformamide (DMF) aqueous solutions with various mass fractions of DMF at T = 298.15 K using a flow-mixing microcalorimeter. A pseudo phase equilibrium model was proposed to simplify the complex aggregation equilibrium and interpret the abnormality in the dilution enthalpy, which together with the McMillan–Mayer approach was used to fit the experimental data to obtain the enthalpic pairwise interaction coefficients and the molar aggregation enthalpies of l-prolinol in DMF aqueous solutions. The results are discussed in terms of the hydrophobic interaction and the interactions between the solvated solutes.     

The P, V, T,x properties of binary aqueous chloride solutions up to T = 573 K and 100 MPa

A highly accurate P, V, T,x model is developed for aqueous chloride solutions of the binary systems, viz. (LiCl + H₂O), (NaCl + H₂O), (KCl + H₂O), (MgCl₂ + H₂O), (CaCl₂ + H₂O), (SrCl₂ + H₂O), and (BaCl₂ + H₂O). The applied ranges of temperature, pressure, and concentrations for the systems (LiCl + H₂O), (NaCl + H₂O), (KCl + H₂O), (MgCl₂ + H₂O), (CaCl₂ + H₂O), (SrCl₂ + H₂O), and (BaCl₂ + H₂O) are (273 K to 564 K, 0.1 MPa to 40 MPa, and 0 to 10 molal), (273 K to 573 K, 0.1 MPa to 100 MPa, and 0 to 6.0 molal), (273 K to 543 K, 0.1 MPa to 50 MPa, and 0 to 4.5 molal), (273 K to 543 K, 0.1 MPa to 40 MPa, and 0 to 3.0 molal), (273 K to 523 K, 0.1 MPa to 60 MPa, and 0 to 6.0 molal), (298 K to 473 K, 0.1 MPa to 2 MPa, and 0 to 2.0 molal) and (273 K to 473 K, 0.1 MPa to 20 MPa, and 0 to 1.6 molal), respectively. Comparison of the model with thousands of experimental data points concludes that the average deviation over the above T, P, m range is 0.020% to 0.066% in density (or volume) for these systems, which indicates high accuracy. From this model, various volumetric properties, such as the apparent molar volume at infinite dilution and isochores of fluid inclusions, can be calculated, thus having a wide range of geological applications, such as reservoir fluid flow simulation and fluid-inclusion study. A computer code is developed for this model and can be downloaded from the website: www.geochem-model.org/programs.htm and online calculations is made available on: www.geochem-model.org/models.htm     

Enthalpy of solution of CO2 in aqueous solutions of methyldiethanolamine at T = 372.9 K and pressures up to 5 MPa

Experimental enthalpies of solution of CO₂ in aqueous solution of methyldiethanolamine (MDEA) of 15 wt% and 30 wt% are reported. The measurements were performed using a flow calorimetric technique at temperature of 372.9 K and pressures range from 0.5 MPa to 5 MPa. Gas solubilities data at same temperature and pressures were derived from the enthalpy data. Experimental enthalpies of solution are combined with available literature data in order to examine pressure and composition influences.     

Enthalpy of solution of CO2 in aqueous solutions of methyldiethanolamine at T = 322.5 K and pressure up to 5 MPa

Enthalpies of solution of CO₂ in aqueous solution of methyldiethanolamine (MDEA) are determined for two different concentrations, respectively, 15 wt% and 30 wt%, at the temperature of 322.5 K and at pressures up to 5 MPa using a flow calorimetric technique. Gas solubilities were consequently deduced from the calorimetric data and compared to available literature values. Experimental enthalpies of solution were compared to direct measurements and to values derived from VLE data available using a simple model based on ideal property considerations.     

Excess thermodynamic properties of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and N-octyl-2-pyrrolidone from T = (298.15 to 323.15) K at atmospheric pressure

Density (ρ), refractive index (n_D) and speed of sound (u) values are measured for the binary mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and N-octyl-2-pyrrolidone over the entire range of mole fraction at temperatures from T = (298.15 to 323.15) K under atmospheric pressure. Using the basic experimental data, various acoustic and excess thermodynamic parameters are calculated and are discussed in terms of molecular interactions between the present investigated binary system. The excess values are fitted to Redlich–Kister polynomial equation to estimate the binary coefficients and standard deviation between the experimental and calculated values. Further, the molecular interactions in the binary mixture system are analysed using the experimental FT-IR spectrum recorded at room temperature.     

Excess enthalpies for mixtures of acrylonitrile and an aromatic hydrocarbon at T = 298.15 K and p = 101325 Pa

Excess molar enthalpies for (acrylonitrile  +  benzene, or methylbenzene, or 1,2-dimethylbenzene, or 1,3-dimethylbenzene, or 1,4-dimethylbenzene, or 1,3,5-trimethylbenzene, or ethylbenzene) atT =  298.15 K and p =  101325 Pa are presented. The excess molar enthalpy range from 531J · mol ^− 1at x =  0.5 for 1,3,5-trimethylbenzene to 210J · mol ^− 1at x =  0.5 for toluene. The Redlich–Kister equation, the NRTL and UNIQUAC models were used to correlate the data.