Showing papers in "Journal of Chemical & Engineering Data in 2007"
TL;DR: In this article, the experimental measurements of the pressure (0.10 < p/MPa < 10.0) and temperature (293.15 < T/K < 393.15) dependence of the density and derived thermodynamic properties, such as the isothermal compressibility, the isobaric expansivity, the thermal pressure coefficient, and the pressure dependence of heat capacity of several imidazolium-based ionic liquids (ILs), were addressed.
Abstract: This work addresses the experimental measurements of the pressure (0.10 < p/MPa < 10.0) and temperature (293.15 < T/K < 393.15) dependence of the density and derived thermodynamic properties, such as the isothermal compressibility, the isobaric expansivity, the thermal pressure coefficient, and the pressure dependence of the heat capacity of several imidazolium-based ionic liquids (ILs), namely, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4]; 3-methyl-1-octylimidazolium tetrafluoroborate, [omim][BF4]; 1-hexyl-3-methylimidazolium hexafluorophosphate, [hmim][PF6]; 3-methyl-1-octylimidazolium hexafluorophosphate, [omim][PF6]; 1-butyl2,3-dimethylimidazolium hexafluorophosphate, [bmmim][PF6]; and 1-butyl-3-methylimidazolium trifluoromethansulfonate, [bmim][CF3SO3]. These ILs were chosen to provide an understanding of the influence of the cation alkyl chain length, the number of cation substitutions, and the anion influence on the properties under study. The influence of water content in the density was also studied for the most hydrophobic IL used, [omim][PF6]. A simple ideal-volume model was employed for the prediction of the imidazolium molar volumes at ambient conditions, which proved to agree well with the experimental results.
372 citations
TL;DR: In this article, the viscosities of the ionic liquids 1-methyl-3-hexylimidazolium hexafluorophosphate, [HMIM]PF6, and 1-butyl-3methylimidrazolium bis(trifluorosulfonyl)imide, [BMIM][Tf2N], have been measured between (0 and 80) °C and at maximum pressures of 238 MPa (HMIM)PF6) and 300 MPa at 75 °C with a falling-body
Abstract: The viscosities of the ionic liquids 1-methyl-3-hexylimidazolium hexafluorophosphate, [HMIM]PF6, and 1-butyl-3-methylimidazolium bis(trifluorosulfonyl)imide, [BMIM][Tf2N], have been measured between (0 and 80) °C and at maximum pressures of 238 MPa ([HMIM]PF6) and 300 MPa ([BMIM][Tf2N]) at 75 °C with a falling-body viscometer. The overall uncertainty is estimated at ± 2 %. Modified Litovitz and Vogel−Fulcher−Tammann (VFT) equations are used to represent the temperature and pressure dependence. The Angell equation relating the strength factor D, the VFT parameter T0, and the glass temperature Tg is confirmed. Densities between (0 and 90) °C at atmospheric pressure with an overall uncertainty estimated at ± 0.000 05 g·cm-3 are also reported.
314 citations
TL;DR: In this paper, five materials were equilibrated with solutions of perfluorooctane sulfonate (PFOS) to characterize adsorption: kaolinite, Ottawa sand standard, synthetic goethite, Lake Michigan sediment, and iron-coated sand from Mappsville, VA.
Abstract: Fluorinated anionic surfactants have drawn considerable attention due to recent work showing significant concentrations in surface waters and biota from around the globe. A detailed understanding of the transport and fate of fluorinated surfactants through soil and like media must include an elucidation of mineral surface chemistry. Five materials were equilibrated with solutions of perfluorooctane sulfonate (PFOS) to characterize adsorption: kaolinite, Ottawa sand standard, synthetic goethite, Lake Michigan sediment, and iron-coated sand from Mappsville, VA. Aqueous and adsorbed PFOS was quantified with LC/MS (mass balance average: 101 ± 12 %, n = 37). The materials showed a near linear increase in adsorption as the equilibrium concentrations increased. Isotherms and calculated solid/solution distribution ratio experiments indicated that PFOS adsorption is significant but smaller than hydrocarbon analogues or organic compounds of similar molecular weight. Surface area normalized adsorption increased fo...
314 citations
TL;DR: In this paper, the authors present new experimental data at high pressure TBAB, w = 0.10, TBAB (w = 0, 0.20, and 0.43) + natural gas semi-clathrate phase boundaries.
Abstract: Tetrabutyl ammonium bromide (TBAB) forms a semi-clathrate hydrate, which can incorporate small gas molecules such as methane and nitrogen. It has recently been used for separation of gases. However, there are very limited experimental data on the phase boundaries of the gas hydrate form in the presence of TBAB. In this work, we present new experimental data at high-pressure TBAB, w = 0.10, TBAB (w = 0.10 and 0.43) + hydrogen, TBAB (w = 0.05, 0.10, 0.20, and 0.30) + methane, TBAB (w = 0.10) + nitrogen, TBAB (w = 0.1 and 0.427) + carbon dioxide, and TBAB (w = 0.05, 0.10, and 0.43) + natural gas semi-clathrate hydrate phase boundaries. In another part of this work, the results of visual observations of the methane + TBAB semi-clathrate hydrate morphology and the methane gas bubbles released from methane + TBAB semi-clathrate hydrates on dissociation are presented. Finally, the effect of TBAB mass fraction on hydrate promotion and the stability of the new semi-clathrate hydrate are presented.
291 citations
TL;DR: In this paper, the van der Waals−Guggenheim equation was used to correlate surface tension with the respective molar volume of the various RTILs, and the developed equation accurately correlated surface tension for this grouping with a maximum estimated error of 0.15 %.
Abstract: Presented are experimental densities and surface tensions of imidazolium-, quaternary ammonium-, and phosphonium-based room-temperature ionic liquids (RTILs) in the temperature range of (298 to 350) K. Densities of the RTILs decrease slightly with temperature in the studied range (298 to 333) K. At 298 K, the densities of the phosphonium-based RTILs ranged from (0.88 to 1.05) g·cm-3, while those of the ammonium-based RTILs ranged from (1.08 to 1.37) g·cm-3. The volume expansivities of phosphonium and ammonium RTILs at 1 atm and 298 K are in the range of (5.5 to 6.5)·10-4 K-1. Surface tension and temperature relationships were established using the van der Waals−Guggenheim equation, σ = Es(1 − T/Tc)n, where n ≈ 1, for the RTILs studied. The Macleod−Sugden−Wright (MSW) equation was used to correlate surface tension with the respective molar volume of the various RTILs. The developed equation can accurately correlate surface tension for this grouping of RTILs with a maximum estimated error of 0.15 % within t...
275 citations
TL;DR: In this article, experimental density measurements are reported, and derived thermodynamic properties, such as the isothermal compressibility, the isobaric expansivity, and the thermal pressure coefficient are presented as Supporting Information for several imidazolium-based ionic liquids (ILs), namely, 1-ethyl-3-methyl-imidazolate bis(trifluoromethylsulfonyl)imide [C2mim][NTf2], 1-heptyl-3]-methyl-IMIDazolate [C7mim
Abstract: Experimental density measurements are reported, and the derived thermodynamic properties, such as the isothermal compressibility, the isobaric expansivity, and the thermal pressure coefficient are presented as Supporting Information for several imidazolium-based ionic liquids (ILs), namely, 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C2mim][NTf2], 1-heptyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C7mim][NTf2], 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C8mim][NTf2], 1-ethyl-3-methyl-imidazolium tetrafluoroborate [C2mim][BF4], and 1-butyl-3-methyl-imidazolium tricyanomethane [C4mim][C(CN)3] in the pressure (0.10 < p/MPa < 30.00) and temperature (293.15 < T/K < 393.15) domains. These ILs were chosen to provide an understanding of the influence of the cation alkyl chain length and the anion influence on the properties under study. Experimental densities are correlated with the Tait equation with an average absolute deviation (AAD) less than 0.04 %. Expe...
271 citations
TL;DR: In this article, the binodal curves were fitted to a three-parameter equation, and the tie-lines were described by the Othmer−Tobias and Bancroft equations.
Abstract: Liquid−liquid equilibrium data have been determined for imidazolium ionic liquid ([C4mim]Cl, [C6mim]Cl, [C4mim]Br, [C6mim]Br, [C8mim]Br, [C10mim]Br) + salt (KOH, K2HPO4, K2CO3, K3PO4) aqueous biphasic systems at T = 298.15 K, and in part at T = (308.15 to 318.15) K. Factors affecting the binodal curves such as nature of ionic liquids and salts and temperature are also studied. The binodal curves are fitted to a three-parameter equation, and the tie-lines were described by the Othmer−Tobias and Bancroft equations. It is found that an increase in temperature caused no significant expansion of the two-phase area. However, the binodal curves became more close to the origin with an increase in alkyl chain length of the ionic liquids (ILs), and the ionic liquids with the Br- anion are easier to form two phases compared to those with the Cl- anion. These data are expected to be useful for the development and design of the extraction process using ILs based on aqueous biphasic systems.
253 citations
TL;DR: In this article, a series of hydroxyl ammonium ionic liquids (ILs) was synthesized and characterized, and the solubilities of SO2 in these synthesized ILs were determined.
Abstract: To explore environmentally benign solvents for absorbing SO2, a series of hydroxyl ammonium ionic liquids (ILs) was synthesized and characterized, and the solubilities of SO2 in these synthesized ILs were determined. It was found that the solubilities of SO2 in these ILs at ambient pressure are quite high, for example, the solubility of SO2 in tri-(2-hydroxyethyl)ammonium lactate is 0.4957 mole fraction and decreases sharply as temperature increase. The absorption and desorption are practically reversible in the synthesized ILs. Comparing with the conventional absorbents such as calcium carbonate (CaCO3), calcium oxide (CaO), and sodium hydroxide (NaOH), the synthesized ILs show two advantages: one is that the ILs can be recycled and repeatedly used, another is that the absorbed SO2 can be reversibly released and recovered as a sulfur resource.
244 citations
TL;DR: In this article, the solubility of quercetin, isoquercitrin, rutin, chrysin, naringenin, and hesperetin was quantified in acetonitrile, acetone, and tert-amyl alcohol.
Abstract: The solubility of quercetin, isoquercitrin, rutin, chrysin, naringenin, and hesperetin was quantified in acetonitrile, acetone, and tert-amyl alcohol. The solubility was strongly affected by both the nature of the solvent and the flavonoid structure. The highest solubility was obtained in acetonitrile for hesperetin (85 mmol·L-1) and naringenin (77 mmol·L-1) and in acetone (80 mmol·L-1) for quercetin. The lowest solubility value was obtained with rutin in acetonirile (0.50 mmol·L-1). The thermodynamic properties of flavonoids were also measured (melting point, enthalpy of fusion, and solid heat capacity) and predicted (liquid heat capacity, solid phase activity, and activity coefficient). Glycosylated flavonoids are characterized by a low melting point and a high enthalpy of fusion compared to the aglycon ones. Contrary to the data reported for other compounds, there is no clear correlation between the solubility of flavonoids and their thermodynamic properties. However, the conformational study showed th...
228 citations
TL;DR: In this paper, the viscosity of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM]BF4) has been measured between (0 and 80) °C with a falling-body viscometer.
Abstract: The viscosity of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) has been measured between (0 and 80) °C with a falling-body viscometer. High-pressure measurements were made at (10, 25, 50, and 75) °C to a maximum pressure of 300 MPa. The expanded uncertainty is estimated at ± 2 %. Modified Litovitz and Vogel−Fulcher−Tammann (VFT) equations are used to represent the temperature and pressure dependence. The Angell equation relating the strength parameter D, the VFT parameter T0, and the glass temperature Tg is again confirmed. Comparing D for the salts [BMIM]PF6, [HMIM]PF6, [OMIM]PF6, [BMIM]BF4, [OMIM]BF4, and [BMIM][Tf2N], we find D([BMIM]+) < D([HMIM]+) < D([OMIM]+) where the anion is common and D([Tf2N]-) < D(BF4-) < D(PF6-) where the cation is common. Densities and thermal expansivities between (0 and 90) °C at atmospheric pressure with overall uncertainty estimated at ± 0.000 05 g·cm-3 and ± 0.02·10-3 K-1 are also reported. The densities are compared with our previously publ...
224 citations
TL;DR: In this paper, the authors measured the viscosity and electrolytic conductivity of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][Tf2N], and its mixtures with water.
Abstract: Thermophysical properties were measured at ambient pressure for a high-purity sample of the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][Tf2N], and its mixtures with water. Density was measured with two vibrating tube densimeters in the temperature range (258.15 to 373.15) K. Dynamic viscosity was determined with a rotational coaxial cylinder measuring system over the temperature range (258.15 to 373.15) K, and kinematic viscosity was measured at (293.15 and 298.15) K with an Ubbelohde capillary viscometer. Speed of sound was measured in a pulse-echo cell over the temperature range (283.15 to 343.15) K. Electrolytic (ionic) conductivity was determined by use of the AC impedance bridge technique over the temperature range (288.15 to 323.15) K. For all of these measurements, special care was taken to control the concentration of water in the sample. The viscosity and electrolytic conductivity of ([C6mim][Tf2N] + H2O) depend strongly on the concentration of water. By Ka...
TL;DR: The densities of five imidazolium-based ionic liquids (ILs) were measured as a function of temperature from (293 to 415) K and over an extended pressure range from (0.1 to 40) MPa using a vibrating-tube densimeter as mentioned in this paper.
Abstract: The densities of five imidazolium-based ionic liquids (ILs) (1-butyl-3-methylimidazolium tetrafluoroborate, [C1C4Im][BF4]; 1-butyl-3-methylimidazolium hexafluorophosphate, [C1C4Im][PF6]; 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [C1C4Im][Tf2N]; 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [C1C2Im][Tf2N]; 1-ethyl-3-methylimidazolium ethylsulfate, [C1C2Im][EtSO4]) were measured as a function of temperature from (293 to 415) K and over an extended pressure range from (0.1 to 40) MPa using a vibrating-tube densimeter. Knowledge of the variation of the density with temperature and pressure allows access to the mechanical coefficients: thermal expansion coefficient and isothermal compressibility. The effects of the anion and of the length of the alkyl chain on the imidazolium ring on the volumetric properties were particularly examined. The mechanical coefficients were compared with those of common organic solvents, water and liquid NaCl. Finally, a prediction model, ...
TL;DR: The ILThermo database as discussed by the authors is a Web-based ionic liquids database that provides users with up-to-date information from publications of experimental thermophysical properties for ionic liquid, including numerical property values, measurement methods, sample purities, purification methods and uncertainties.
Abstract: The development, scope, and functionality of the Web-based ionic liquids database, ILThermo, are described. The database is available free to the public and aims to provide users worldwide with up to date information from publications of experimental thermophysical properties for ionic liquids, including numerical property values, measurement methods, sample purities, purification methods, and uncertainties. The database can be searched in terms of the ions constituting the ionic liquids, the ionic liquids themselves, and their properties and through literature citation information
TL;DR: In this article, a new model for calculating the viscosity of aqueous solutions has been developed based on a critical review of the literature for solutions of one solute in water, with over 9000 points included.
Abstract: A new model for calculating the viscosity of aqueous solutions has been developed. Parameters for 74 solutes were established based on a critical review of the literature for solutions of one solute in water, with over 9000 points included. The average difference between the calculated and experimental viscosities is less than 0.1 %, and the standard deviation of this difference is 3.7 % of the average experimental viscosity. The model was validated by estimating published viscosity for systems of more than one solute in water. The average difference between experimental and calculated values for 1700 points is −2.7 %, and the standard deviation of this difference is 16 % of the average experimental viscosity. The median standard deviation of the difference between experimental and calculated values is 3.5 % of the experimental viscosity. The solutes studied are (NH4)2SO4, AlCl3, BaCl2, Ca(NO3)2, CaCl2, Cd(NO3)2, CdCl2, CdSO4, CoCl2, CoSO4, Cr2(SO4)3, CrCl3, Cu(NO3)2, CuCl2, CuSO4, Fe2(SO4)3, FeCl2, FeSO4...
TL;DR: In this paper, the properties of binary systems formed by ionic liquids with a common anion, such as 1-hexyl-3-methylimidazolium tetrafluoroborate + 1-ethyl-3 -methyloride-naphosophate, were determined.
Abstract: Densities, isobaric thermal expansivities, and excess enthalpies were determined for the binary systems formed by ionic liquids with a common anion, 1-hexyl-3-methylimidazolium tetrafluoroborate + 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-hexyl-3-methylimidazolium tetrafluoroborate + 1-butyl-3-methylimidazolium tetrafluoroborate, and by those with a common cation, 1-butyl-3-methylimidazolium tetrafluoroborate + 1-butyl-3-methylimidazolium methylsulfate and 1-butyl-3-methylimidazolium tetrafluoroborate + 1-butyl-3-methylimidazolium hexafluorophosphate. Volumetric properties were obtained by means of a vibrating tube densimeter, whereas Calvet microcalorimetry was used to determine the excess enthalpies. Due to the high viscosity of the samples, nonstandard experimental techniques had to be used to obtain the results. The experimental data are interpreted on the basis of the chemical structure of the ionic liquids.
TL;DR: In this paper, the speed of sound and density of mixtures of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]) with methanol, ethanol, 1-propanol, and water, as well as of the pure components have been experimentally measured over the whole range of compositions at T = (278.15 to 338.15) K and atmospheric pressure.
Abstract: The speed of sound and density of mixtures of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]) with methanol, ethanol, 1-propanol, and water, as well as of the pure components have been experimentally measured over the whole range of compositions at T = (278.15 to 338.15) K and atmospheric pressure. From these experimental data, the excess molar volume, excess isentropic compressibility, and excess speed of sound have been calculated and fitted to an extended version of the Redlich−Kister equation, which takes into account the dependence on composition and temperature simultaneously. The Prigogine−Flory−Patterson theory has also been used to explain the behavior of these systems.
TL;DR: In this article, 1-butyl-3-methylimidazolium methyl sulfate was used as a solvent in the extraction process for the separation of azeotropic mixtures.
Abstract: Density, speed of sound, refractive index, dynamic viscosity, and surface tension measurements of 1-butyl-3-methylimidazolium methyl sulfate have been made as a function of temperature. The synthesis of the ionic liquid is given. The low viscosity of the ionic liquid suggests its use as a solvent in the extraction process for the separation of azeotropic mixtures. The thermal expansion coefficient of the ionic liquid was calculated from the density, and the results are discussed. An analysis of the influence of the alkyl chain length of the cation on the density was performed by comparison with recently published values.
TL;DR: In this article, the thermal conductivities of 11 ionic liquids were determined, over the temperature range from 293 K to 353 K, at atmospheric pressure, using an apparatus based on the transient hot-wire method.
Abstract: The thermal conductivities of 11 ionic liquids were determined, over the temperature range from 293 K to 353 K, at atmospheric pressure, using an apparatus based on the transient hot-wire method. For each of the ionic liquids studied, the thermal conductivities were found to be between (0.1 and 0.2) W·m-1·K-1, with a slight decrease observed on increasing temperature. The uncertainty is estimated to be less than ± 0.002 W·m-1·K-1. In all cases, a linear equation was found to give a good fit to the data. The effects of water content and chloride content on the thermal conductivities of some of the ionic liquids were investigated. In each case, the thermal conductivities of the water + ionic liquid and chloride + ionic liquid binary mixtures were found to be less than the weighted average of the pure component thermal conductivities. This effect was adequately modeled using the Jamieson correlation. Chloride contamination at typical postsynthesis levels was found to have no significant effect on the thermal...
TL;DR: The viscosity and refractive index of room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6] in tetrahydrofuran, dimethylsulfoxide, methanol, and acetonitrile have been measured at 298.15 K.
Abstract: The viscosity and refractive index of the solutions of room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6] in tetrahydrofuran, dimethylsulfoxide, methanol, and acetonitrile have been measured at 298.15 K. The density and speed of sound for solutions of [BMIM][PF6] + tetrahydrofuran or dimethylsulfoxide have also been measured. The changes in viscosity and molar refraction, the excess molar volume, and deviation in isentropic compressibility have been adequately fitted to the Redlich−Kister polynomial.
TL;DR: In this article, the thermal stability of ionic liquids has been evaluated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).
Abstract: Heat capacity, glass-transition, crystallization, and melting temperatures of 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO4]) and 1-butyl-3-methylimidazolium methylsulfate ([Bmim][MeSO4]) ionic liquids (ILs) have been determined by differential scanning calorimetry (DSC). Their thermal stabilities have been analyzed by thermogravimetric analysis (TGA). Given the effect of the heating rate over the decomposition temperatures, isothermal TGA experiments are proposed as a more appropriate method to evaluate the thermal stability of the ILs. Inside the working range (−150 °C to 30 °C), [Emim][EtSO4] and [Bmim][MeSO4] present a glass-transition temperature of −78.4 °C and −91.9 °C, respectively. [Bmim][MeSO4] has a melting temperature of −4.1 °C. The Cp was determined in a working range (10 °C to 100 °C) where its value increases lineally with temperature.
TL;DR: In this article, the authors measured the viscosities, densities, and speeds of sound of 1-ethyl-3-methylimidazolium ethyl sulfate (EMISE) with methanol, 1-propanol, and 2-Propanol at T = (298.15, 313.15 and 328.15) K and refractive indices at 298.15 K and at atmospheric pressure have been measured over the whole composition range.
Abstract: In this contribution, dynamic viscosities, densities, and speeds of sound of 1-ethyl-3-methylimidazolium ethyl sulfate (EMISE) with methanol, 1-propanol, and 2-propanol at T = (298.15, 313.15, and 328.15) K and refractive indices at T = 298.15 K and at atmospheric pressure have been measured over the whole composition range. Excess molar volumes, excess molar isentropic compressions, and viscosity deviations for the binary systems from T = 298.15 K to T = 328.15 K and refractive deviations at 298.15 K have been calculated and were satisfactorily fitted to a Redlich−Kister equation to give the fitting parameters and the root-mean-square deviations.
TL;DR: The adsorption of the dyes Basic Red 46 (BR46) and Reactive Yellow 176 (RY176) from aqueous solution onto natural and modified zeolites has been investigated in this article.
Abstract: The adsorption of the dyes Basic Red 46 (BR46) and Reactive Yellow 176 (RY176) from aqueous solution onto natural and modified zeolites has been investigated. The surfactants cetyltrimethylammonium...
TL;DR: In this paper, the adsorption of Reactive Black 5 and Reactive Red 239 in aqueous solution on cetyltrimethylammonium bromide (CTAB)−zeolite was studied in a batch system.
Abstract: The adsorption of Reactive Black 5 and Reactive Red 239 in aqueous solution on cetyltrimethylammonium bromide (CTAB)−zeolite was studied in a batch system. The natural zeolite and CTAB-modified zeolite were characterized by FT-IR and SEM analysis. Experiments were performed at different conditions such as initial dye concentration, contact time, temperature, and pH. CTAB modification covered the zeolite surface with positive charges, and the adsorption capacity of zeolite increased. The adsorption capacity of Reactive Red 239 was found to be two times higher than Reactive Blue 5 due to the hydrophilicity of the dye molecules. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms at different temperatures, and the Freundlich agrees very well with the experimental data. The pseudo-second-order model provided a very good fitting (R2 > 0.992) for the two anionic dyes. The calculated maximum adsorption capacity (qe,calcd) increased with increasing initial dye concentr...
TL;DR: The second dissociation constants of the amino acids β-alanine, taurine, sarcosine, 6-aminohexanoic acid, dl-methionine, glycine, l-phenylalanine and l-proline have been determined from electromotive force measurements at temperatures from (293 to 353) K.
Abstract: The second dissociation constants of the amino acids β-alanine, taurine, sarcosine, 6-aminohexanoic acid, dl-methionine, glycine, l-phenylalanine, and l-proline and the third dissociation constants of l-glutamic acid and l-aspartic acid have been determined from electromotive force measurements at temperatures from (293 to 353) K. Experimental results are reported and compared to literature values. Values of the standard state thermodynamic properties are derived from the experimental results and compared to the values of commercially available amines used as absorbents for CO2 capture.
TL;DR: In this paper, the densities of mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1 -butyl 3methyloridazolate tetrafluoroborate ([BF4]) with acetonitrile over the entire composition range at T = (293.15 to 343.15) K and with benzene and 1-propanol over the miscible composition range in the presence of 1
Abstract: Densities of mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) with acetonitrile over the entire composition range at T = (293.15 to 343.15) K and with benzene and 1-propanol over the miscible composition range at T = (293.15 to 343.15) K were measured by a vibrating tube densimeter. Density measurements were used to compute the excess molar volumes, VE. The VE values have been fitted to the Redlich−Kister equation. VE values are negative for all the mixtures over the miscible range and become more negative with increasing temperature. The VE values for benzene mixtures are the most negative in the investigation.
TL;DR: In this paper, the solubilities of C2H4 and CO2 and the interactions of polar and nonpolar solutes with the novel ionic liquids (ILs) 1-butyronitrile-3-methylimidazolium bis(trifluoromethylsulfonyl) imidate (CpMIm[NTf2]), 1-methyl-dimethyliminamide (dimINET) dicyanamide (cpMMIm[N(CN)2), 1buty
Abstract: The solubilities of C2H4 and CO2 and the interactions of polar and nonpolar solutes with the novel ionic liquids (ILs) 1-butyronitrile-3-methylimidazolium bis(trifluoromethylsulfonyl) imidate (CpMIm[NTf2]), 1-butyronitrile-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imidate (CpMMIm[NTf2]), 1-butyronitrile-3-methylimidazolium dicyanamide (CpMIm[N(CN)2]), 1-butyronitrile-2,3-dimethylimidazolium dicyanamide (CpMMIm[N(CN)2]), 1-butyl-3-methylimidazolium palmitate (BMIm[n-C16H33COO]), and 1-butyl-3-methylimidazolium stearate (BMIm[n-C18H35COO]) were studied by gas chromatography at infinite dilution at T = (303.15, 313.15, 323.15, and 333.15) K. Henry's law constant kH of C2H4 and CO2 gas, infinite dilution activity coefficient γ∞, molar enthalpies of solution ΔsolH∞, and partial molar excess enthalpies of solution ΔHE∞ and of Gibbs energies ΔGE∞ were determined for polar and nonpolar solutes in these novel ILs. Compared with the 1,3-dialkylimidazolium ILs, cyano functional group substitution on the a...
TL;DR: In this paper, the phase diagrams of seven fatty acid binary mixtures were obtained by differential scanning calorimetry (DSC), and the spline technique was used to compare the results of this work with prior results available in the literature for some of the investigated systems.
Abstract: In the present work the phase diagrams of seven fatty acid binary mixtures were obtained by differential scanning calorimetry (DSC). These mixtures were formed by capric acid (C10:0) with lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), or stearic acid (C18:0) and by lauric acid (C12:0) with myristic acid (C14:0), palmitic acid (C16:0), or stearic acid (C18:0). The spline technique was used to compare the results of this work with prior results available in the literature for some of the investigated systems. The occurrence of the eutectic point in all systems and of the peritectic point in some of the systems was observed. The occurrence of the peritectic point can be associated with the difference in the number of carbon atoms of the fatty acid chains used in the mixture. The approach suggested by Slaughter and Doherty (Chem. Eng. Sci. 1995, 50, 1679−1694) was used to model the solid phase, and the liquid phase was modeled using the Margules-2-suffix, Margules-3-suffix, UNIFAC Dortmund...
TL;DR: In this paper, the static dielectric constants of acetonitrile/water mixtures in the whole composition range and within the temperature range from (15 to 60) °C have been measured.
Abstract: Static dielectric constants of acetonitrile/water mixtures in the whole composition range and within the temperature range from (15 to 60) °C have been measured. The values were fitted to a unique equation as a simultaneous function of temperature and acetonitrile composition. Densities of these mixtures at temperatures from (5 to 55) °C and different compositions have been collected from the literature. The complete data set was critically analyzed, the outliers were excluded, and the remaining values were also fitted to a unique equation as a function of temperature and acetonitrile composition. From the dielectric constants and densities, the activity coefficients of ions can be calculated by means of the Debye−Huckel approach, allowing the study of the ionic equilibria and determination of reference pH values or acidity constants in any acetonitrile/water mixture at any temperature within the studied range.
TL;DR: In this article, the authors examined the effect of structural components of an ionic liquid (IL), including the choice of the anion, alkyl chain length on the cation, and substitution on the Cation, on the mutual solubility with water and with 1-octanol.
Abstract: This study examines the effect of structural components of an ionic liquid (IL), including the choice of the anion, alkyl chain length on the cation, and substitution on the cation, on the mutual solubility with water and with 1-octanol. This is important because ionic liquids have been shown to be good replacements for organic extraction solvents in some liquid separations. In addition, we use the measured data to predict 1-octanol/water partition coefficients for the ionic liquids using the nonrandom two liquid (NRTL) and electrolyte nonrandom two liquid (eNRTL) excess Gibbs energy models. Specifically, the mutual solubilities of 15 different imidazolium, pyridinium, and quaternary ammonium ionic liquids with water were measured at (23.5 ± 1) °C. An increase in the alkyl chain length or the substitution decreases the mutual solubility with water. The [BF4]- and [B(CN)4]- anions are significantly more hydrophilic than [PF6]-, [(CF3SO2)2N]-, and [(CF3SO2)3C]-. The mutual solubilities of 10 ILs with 1-octa...
TL;DR: In this article, the experimental binary data sets were independently fitted with the electrolyte NRTL model, and the parameters of Mock's model were estimated for each binary system, which agreed very well with the experimental one.
Abstract: Isobaric vapor−liquid equilibria for the binary systems acetone + methanol, acetone + 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]), and methanol + [emim][triflate] as well as the vapor−liquid equilibrium for the acetone + methanol + [emim][triflate] ternary system have been obtained at 100 kPa using a recirculating still. The addition of the ionic liquid to the solvent mixture produced an important salting-out effect, and the azeotrope tended to disappear for small contents of ionic liquid. The experimental binary data sets were independently fitted with the electrolyte NRTL model, and the parameters of Mock's model were estimated for each binary system. These parameters were used to predict the ternary vapor−liquid equilibrium which agreed very well with the experimental one.