排序方式: 共有37条查询结果,搜索用时 15 毫秒
21.
Urszula Domańska Maciej Zawadzki M. Marc Tshibangu Deresh Ramjugernath Trevor M. Letcher 《The Journal of chemical thermodynamics》2010,42(9):1180-1186
Quinolinium ionic liquid has been prepared from 1-butylquinolinium bromide as a substrate. The work includes specific basic characterization of synthesized compound by NMR spectra, elementary analysis and water content. The basic thermal properties of the pure IL, i.e. melting and glass-transition temperatures, as well as the enthalpy of fusion have been measured using a differential scanning microcalorimetry technique (DSC). (Solid + liquid) phase equilibria (SLE) and (liquid + liquid) phase equilibria (LLE) for the binary systems: ionic liquid (IL) N-butylquinolinium bis{(trifluoromethyl)sulfonyl}imide, {([BQuin][NTf2]) + aromatic hydrocarbon (benzene, or toluene, or methylbenzene, or propylbenzene, or thiophene), or an alcohol (ethanol, or 1-butanol, or 1-hexanol, or 1-octanol, or 1-dodecanol)} have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (260 to 330) K. For the binary systems, the simple eutectic diagrams were observed with immiscibility in the liquid phase with an upper critical solution temperature (UCST). For mixtures with alcohols, it was observed that with increasing chain length of an alcohol the solubility decreases and the UCST increases. In the case of mixture (IL + benzene, or alkylbenzene, or thiophene) the eutectic systems with mutual immiscibility in the liquid phase with very high UCSTs were observed. These points were not detectable with our method and they were observed at low ionic liquid mole fraction. Densities at high temperatures were determined and extrapolated to T = 298.15 K. Well-known UNIQUAC, and NRTL equations have been used to correlate experimental SLE data sets. For the systems containing immiscibility gaps {IL + an alcohol} parameters of the LLE correlation equation have been derived using only the NRTL equation. 相似文献
22.
Hamisu Ibrahim Neil Anthony Koorbanally Deresh Ramjugernath Dr. Muhammad Dabai Bala Vincent Onserio Nyamori 《无机化学与普通化学杂志》2012,638(14):2304-2309
The reaction of 1‐methylimidazole and α,α‐dibromo‐p‐xylene was followed by a metathesis reaction with fluorinated anion sources, which yielded new fluorinated imidazolium salts [C6H4(CH2(C4H6N2)2]2+ 2[A]– where A = BF4 ( 2 ), PF6 ( 3 ), CF3SO3 ( 4 ), and CF3COO ( 5 ). The compounds were characterized by 1H‐, 13C‐, 19F‐, 31P NMR, and IR spectroscopy. Single crystal X‐ray diffraction data of compounds 2 , 3 , and 4 were also reported, whereas compound 5 was found to be a liquid. The solid compounds crystallized in the monoclinic P21/c space group and have similar crystallographic parameters. The study revealed that the different fluorinated anions affected the spatial arrangement of atoms and the extent of cation–anion interactions, hence, influenced the stability and coordination properties of the imidazolium salts. A trend was observed which related the strength of cation–anion interaction to physical properties such as melting point. 相似文献
23.
Eugene Olivier Trevor M. Letcher Paramespri Naidoo Deresh Ramjugernath 《The Journal of chemical thermodynamics》2010,42(5):646-650
Activity coefficients at infinite dilution were determined for 24 solutes: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes and alcohols in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate, [OMIM][PF6], by gas–liquid chromatography at three different temperatures T = (313.15, 323.15, and 333.15) K. The partial molar excess enthalpy values at infinite dilution were calculated from the experimental data over the same temperature range. Capacities and selectivities at infinite dilution for the systems hexane/benzene and methanol/benzene were determined from the experimental data and compared to the literature values for other ionic liquids, as well as for industrial molecular solvents. The influence of the cation and anion of the ionic liquid on the activity coefficient is discussed, as well as the usefulness of [OMIM][PF6] in separating organic liquids. 相似文献
24.
Configurational-bias Monte Carlo simulations were carried out in the Gibbs ensemble to generate phase equilibrium data for several carboxylic acids. Pure component coexistence densities and saturated vapor pressures were determined for acetic acid, propanoic acid, 2-methylpropanoic acid, and pentanoic acid, and binary vapor-liquid equilibrium (VLE) data for the propanoic acid + pentanoic acid and 2-methylpropanoic acid + pentanoic acid systems. The TraPPE-UA force field was used, as it has recently been extended to include parameters for carboxylic acids. To simulate the branched compound 2-methylpropanoic acid, certain minor assumptions were necessary regarding angle and torsion terms involving the -CH- pseudo-atom, since parameters for these terms do not exist in the TraPPE-UA force field. The pure component data showed good agreement with the available experimental data, particularly with regard to the saturated liquid densities (mean absolute errors were less than 1.1%). On average, the predicted critical temperature and density were within 1% of the experimental values. All of the binary simulations showed good agreement with the experimental x-y data. However, the TraPPE-UA force field predicts saturated vapor pressures of pure components that are larger than the experimental values, and consequently the P-x-y and T-x-y data of the binary systems also deviate from the measured data. 相似文献
25.
26.
Matthew Lasich Deresh Ramjugernath 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(5):83
Clathrate hydrates are an ice-like material consisting of gas molecules confined within cavities in a crystalline water lattice. Phase equilibria of clathrate hydrates systems was described using the statistical mechanical theory of van der Waals and Platteeuw. This theory makes use of the fractional occupancy of cavities within the clathrate hydrate lattice in the determination of chemical equilibria. Classical density functional theory with intermolecular interactions restricted to the first hydration shell was employed to determine the fractional occupancy. In addition to the external field describing the gas-water interactions, the effect of a gravitational field was introduced. The results of the calculations show that although the gravitational potential term may be orders of magnitude smaller than the thermal kinetic energy of the gas species or the hydrogen-bond energy holding the clathrate lattice together, it can nevertheless influence the phase equilibrium of the clathrate hydrate system to some degree. The effect of the magnitudes of both the gravitational potential and the local gravitational field are considered too. 相似文献
27.
Lebouvier A. Iwarere S. A. Ramjugernath D. Fulcheri L. 《Plasma Chemistry and Plasma Processing》2015,35(1):91-106
Plasma Chemistry and Plasma Processing - In this paper, the behaviour of a tetrafluoromethane (CF4) plasma arc under conditions of low current (0.25–0.4 A) and very high pressure (10... 相似文献
28.
Kaniki Tumba Prashant Reddy Paramespri Naidoo Deresh Ramjugernath 《The Journal of chemical thermodynamics》2011,43(5):670-676
Activity coefficients at infinite dilution have been measured by gas–liquid chromatography for 27 organic solutes (n-alkanes, 1-alkenes, 1-alkynes, cycloalkanes, aromatics, alcohols, and ketones) in the ionic liquid trihexyl(tetradecyl)phosphonium tetrafluoroborate [3C6C14P][BF4]. The measurements were carried out at four different temperatures viz. T = (313.15, 333.15, 353.15, and 373.15) K. From the experimental data, partial molar excess enthalpy values at infinite dilution were calculated for the experimental temperature range. The selectivity values for the separation of n-hexane/benzene, cyclohexane/benzene, and methanol/benzene mixtures were determined from the experimental infinite dilution activity coefficient values. These values were compared to those available in the literature for other ionic liquids and commercial solvents, so as to assess the feasibility of employing [3C6C14P][BF4] in solvent-enhanced industrial separations. 相似文献
29.
Prashant Reddy Kaleng J. Chiyen Nirmala Deenadayalu Deresh Ramjugernath 《The Journal of chemical thermodynamics》2011,43(8):1178-1184
Activity coefficients at infinite dilution have been determined for 27 solutes, viz. water and organic compounds (n-alkanes, cycloalkanes, 1-alkenes, 1-alkynes, aromatics, alcohols, and ketones) in the ionic liquid Ammoeng 100, by gas–liquid chromatography at four different temperatures, T = (308.15, 313.15, 323.15, and 333.15) K. Columns with different phase loadings (20 to 24)% of the ionic liquid in the stationary phase were employed to obtain values at each temperature investigated. Partial molar excess enthalpies at infinite dilution () were calculated for the solutes from the temperature dependency relationship of the values for the temperature range in this study. The uncertainties in the determinations of the and values are 6% and 10%, respectively. Selectivity values at infinite dilution (), have been computed from the values to assess the potential candidacy of the Ammoeng 100 ionic liquid for the separation of alkane/alcohol mixtures. The results from this study have been compared to those available for several ionic liquids from previous investigations. 相似文献
30.
I. Bahadur N. Deenadayalu P. Naidoo D. Ramjugernath 《Journal of solution chemistry》2014,43(4):787-803
In this paper density, sound velocity, and refractive index for the binary system (butyric acid + hexanoic acid) were measured over the entire composition range and at 5 K intervals in the temperature range 293.15–313.15 K. The excess molar volumes, isentropic compressibilities, excess isentropic compressibilities, deviation in refractive indices, molar refractions, and deviation in molar refractions were calculated by using the experimental densities, sound velocities, and refractive indices, respectively. The Redlich–Kister equation was used to fit the excess molar volume, excess isentropic compressibility, deviation in refractive index and deviation in molar refraction data. The Lorentz–Lorenz approximation was used to correlate the excess molar volume from the deviation in refractive index and also to predict the density from refractive index or the refractive index from density of the binary mixtures. Four sound velocity mixing rules were tested and the best model for the systems studied in this work was the Berryman mixing rule. The thermodynamic properties are discussed in terms of intermolecular interactions between the components of the mixtures. 相似文献