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1.
《Physics and Chemistry of Liquids》2012,50(4):475-480
Abstract Density and viscosity measurements on the binary mixtures of methanol+p-xylene, n-propanol+p-xylene and n-butanol+p-xylene at 303.15, 313.15 and 323.15K are reported The representation of the data by common mixing rules is also studied. 相似文献
2.
X. N. Yang 《Journal of solution chemistry》1998,27(3):261-272
A diaphragm cell has been used to measure mutual diffusion coefficients at 25°C for four binary nonelectrolyte mixtures: ethylbenzene + n-hexane, carbon tetrachloride + ethylbenzene, cyclohexane + p-xylene, and 1,2-dichloroethane + cyclohexane. A free-volume predictive approach for binary mutual diffusion coefficients was developed and tested. Only infinite dilution diffusion coefficients, some readily available pure substance data, and UNIFAC group contribution parameters are used in the model. No binary equilibrium thermodynamic information is required. For 73 binary systems with an overall average absolute deviation of 5.2%, it has been shown that the developed method is better than two commonly available reference methods for the prediction of liquid diffusion coefficients. 相似文献
3.
用于聚合物溶液扩散系数计算的活度系数模型比较 总被引:2,自引:0,他引:2
用40个聚合物溶液体系的实验数据,对三个有代表性的活度系数模型用于计算联系自扩散系数和互扩散系数的热力学因子的精度进行了比较,结果表明三个模型的精度相近,误差一般在20%左右。,因而本工作揭示了聚合物溶注保由自扩散系数计算与扩散系数的一个潜在问题。即由于活度系数模型计算热力学因子误差较大所带来的较大不确定性。 相似文献
4.
Knowledge of the viscosity of binary mixtures is of great importance in many industrial processes. Rarely can the viscosity
of mixtures be obtained from the sum of the viscosities of the pure components.
The theoretical study of the viscosity of mixtures is generally complicated. Numerous empirical correlation models have been
proposed. The present study proposes a new empirical correlation equation, based on lineal behavior. The equation can easily
be used with one, two or three parameters, and in many cases it improves upon the models that are commonly used. Likewise,
the excess viscosity calculated with the proposed equation generally yield more satisfactory results than those obtained with
the polynomial equation of Redlich-Kister. 相似文献
5.
Binary mutual diffusion coefficients D can be estimated from the width at half height W
1/2 of Taylor dispersion profiles using D=(ln 2)r
2
t
R/(3W
2
h) and values of the retention time t
R and dispersion tube radius r. The generalized expression D
h=−(ln h)r
2
t
R/(3W
2
h
) is derived to evaluate diffusion coefficients from peak widths W
h
measured at other fractional heights (e.g., (h = 0.1, 0.2,…,0.9). Tests show that averaging the D
h
values from binary profiles gives mutual diffusion coefficients that are as accurate and precise as those obtained by more
elaborate nonlinear least-squares analysis. Dispersion profiles for ternary solutions usually consist of two superimposed
pseudo-binary profiles. Consequently, D
h
values for ternary profiles generally vary with the fractional peak height h. Ternary profiles with constant D
h
values can however be constructed by taking appropriate linear combinations of profiles generated using different initial
concentration differences. The invariant D
h
values and corresponding initial concentration differences give the eigenvalues and eigenvectors for the evaluation of the
ternary diffusion coefficient matrix. Dispersion profiles for polymer samples of N i-mers consist of N superimposed pseudo-binary profiles. The edges of these profiles are enriched in the heavier polymers owing to the decrease
in polymer diffusion coefficients with increasing polymer molecular weight. The resulting drop in D
h
with decreasing fractional peak height provides a signature of the polymer molecular weight distribution. These features
are illustrated by measuring the dispersion of mixed polyethylene glycols. 相似文献
6.
This paper presents in detail a robust, efficient and accurate methodology for the computation of equilibrium composition in gaseous mixtures. The methodology is founded on the concept of the chemical basis, which is defined and formalized using a powerful matricial approach. The method is specially designed to be general, thus providing basic thermodynamic data in several areas, such as combustion, plasma chemistry and, more generally speaking, computational fluid dynamics. The performance of the method is given in terms of CPU usage and the computed results are compared with those in the published literature. The method is shown to yield results of very high quality in terms of accuracy and smoothness. 相似文献
7.
Taylor dispersion equipment installed at the University of Coimbra for the measurement of diffusion in liquids has been tested
to ensure adequate accuracy and precision by measuring mutual diffusion coefficients for binary aqueous solutions of sucrose,
glycine, lithium chloride, potassium chloride, and hydrochloric acid at 298.15 K. In addition, binary mutual diffusion coefficients
for aqueous solutions of lactic acid (not previously reported in the literature) have been measured at 298.15 and 303.15 K
and concentrations up to 0.20 mol-dm−3. 相似文献
8.
Coupling the corresponding states theory with the dimensional analysis method, the viscosity correlations for calculating gas-phase viscosity at normal pressures were proposed by correlating the non-dimensional viscosity η* with the reduced temperature Tr and the critical compressibility factor ZC. The correlations would apply to monatomic gases, diatomic gases, hydrocarbons and halogenated hydrocarbons. Compared the calculated results with literature data, the absolute average of relative deviations (AADs) of the correlations are 0.47% for monatomic gases, 0.57% for diatomic gases, 0.37% for hydrocarbons and 0.43% for halogenated hydrocarbons, respectively.Meanwhile, the viscosity correlations of five halogenated hydrocarbons R32, R125, R134a, R143a and R152a were presented. The correlations were established by correlating the reduced residual viscosity Δηr and the reduced density ρr on the base of the corresponding states theory. Compared the calculated results with literature data, the AADs of the correlations are 2.16%, 2.39%, 1.10%, 1.41% and 1.38%, respectively. 相似文献
9.
Totchasov E. D. Nikiforov M. Yu. Luk'yanchikova I. A. Al'per G. A. 《Russian Journal of Applied Chemistry》2001,74(5):822-829
The results of calculating the viscosity of binary nonelectrolyte systems by methods obviating fitting parameters were compared. A method was proposed for calculating the viscosity of n-alkanol-n-alkane solutions with account of the molecular association by the free-volume theory accurately to within 7.9%. 相似文献
10.
The conductivities of binary mixtures of glycerine and water were measured at 20°C by means of a transient method. The equation
describing the correlation between concentration and thermal conductivity was determined. The equation can be used for determining
concentrations in mixtures. The results show that (1) the error in the determination of the molar concentration of water in
mixtures is less than 1%, (2) the time of measurement is 1 s, (3) this method can be used for on-line analysis in production
control.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Excess Molar Volume and Viscosity of Isobutyric Acid + Water Binary Mixtures Near and Far Away from the Critical Temperature 总被引:1,自引:0,他引:1
The excess molar volume VE, shear viscosity deviation Δη and excess Gibbs energy of activation ΔG∗E of viscous flow have been investigated by using density (ρ) and shear viscosity (η) measurements for isobutyric acid + water (IBA+W) mixtures over the entire range of mole fractions at five different temperatures,
both near and close to the critical temperature (2.055K ≤ (T−Tc)≤ 13.055K). The results were also fitted with the Redlich–Kister equation. This system exhibited very large negative values
of VE and very large positive values of Δη due to increased hydrogen bonding interactions and correlation length between unlike molecules in the critical region and
to very large differences between the molar volumes of the pure components at low temperatures. The activation parameters
ΔH∗ and ΔS∗ have been also calculated and show that the critical region has an important effect on the volumetric properties. 相似文献
12.
A new sensitive, simple, rapid, and precise RP LC method with hydrochlorothiazide as internal standard has been developed for resolving two binary mixtures, perindopril with indapamide and captopril with indapamide, in pharmaceutical formulations. The drugs were separated at room temperature on a 250 mm × 4.6 mm, 5-μm particle, cyanopropyl column with 10 mm KH2PO4, pH 6.0-methanol 55:45 (v/v) as mobile phase at a flow rate of 1 mL min?1. Detection was at 210 nm. Factors affecting the separation process were studied and optimized. The linearity, accuracy, and precision of the method were good, and the method was successfully applied to the determination of the two binary combinations in synthetic mixtures and commercial pharmaceutical products. 相似文献
13.
The viscosity of pure n-alkanes and n-alkane mixtures was studied by molecular dynamics (MD) simulations using the Green–Kubo method. n-Alkane molecules were modeled based on the Transferable Potential for Phase Equilibria (TraPPE) united atom force field. MD simulations at constant number of molecules or particles, volume and temperature (NVT) were performed for n-C8 up to n-C96 at different temperatures as well as for binary and six-component n-alkane mixtures which are considered as prototypes for the hydrocarbon wax produced during the Gas-To-Liquid (GTL) Fischer–Tropsch process. For the pure n-alkanes, good agreement between our simulated viscosities and existing experimental data was observed. In the case of the n-alkane mixtures, the composition dependence of viscosity was examined. The simulated viscosity results were compared with literature empirical correlations. Moreover, a new macroscopic empirical correlation for the calculation of self-diffusion coefficients of hydrogen, carbon monoxide, and water in n-alkanes and mixtures of n-alkanes was developed by combining viscosity and self-diffusion coefficient values in n-alkanes. The correlation was compared with the simulation data and an average absolute deviation (AAD) of 11.3% for pure n-alkanes and 14.3% for n-alkane mixtures was obtained. 相似文献
14.
15.
Ana C. F. Ribeiro Marisa C. F. Barros Luis M. P. Verissimo Victor M. M. Lobo Artur J. M. Valente 《Journal of solution chemistry》2014,43(1):83-92
Although aspartic acid is a non-essential amino acid, its importance is crucial for a major metabolic pathway and it is present in different types of foods. This highlights the need of a better knowledge of its transport properties. A Taylor dispersion technique has been used for measuring mutual diffusion coefficients of binary aqueous solutions of l-aspartic acid, an associated electrolyte, and the corresponding salt sodium l-aspartate, which behaves as a non-associated electrolyte, at 298.15 K and concentrations ranging from (0.001 to 0.100) mol·dm?3. Thermodynamic factors for the diffusion of aspartic acid and sodium aspartate have been estimated on the basis of the Onsager–Fuoss equation. Furthermore, experimental diffusion coefficients of aspartic acid are compared with those computed by the modified Onsager–Fuoss equation, applied for partially dissociated electrolytes. 相似文献
16.
《Analytical letters》2012,45(7):1224-1241
The combined use of a competing ligand exchange (CLE) method and a diffusive gradient in thin films (DGT) technique in a quasi-labile system provides a better understanding of dynamic metal (Cu and Ni) complexes in the presence of humic substances of different origins. The CLE and DGT techniques provide total labile (dynamic) metal complexes (Cu and Ni) and their dissociation rate constants in environmental systems. DGT was found to estimate lower concentrations of labile metal complexes than CLE. These discrepancies were caused by diffusion controlled metal flux (towards the binding resin gel) in the diffusive gel of DGT. The interactions of Cu and Ni with humic acids are stronger than their interactions with fulvic acid and natural organic matter. Changes in the lability of Ni and Cu complexes (complexed with humic substances of different origins) with the changing analytical detection window indicate that the complexes of these metals were formed with different binding sites with diverse binding energies in the humic substances. The combination of these two techniques was found to be very useful in determining diffusion coefficients of labile metal-humate complexes in quasi-labile systems. The values of diffusion coefficients of labile Ni and Cu complexes determined in this study are in good agreement with limited results from the literature. This finding is novel and can be very useful in further improving our understanding of the metal-humate interactions in natural environments. 相似文献
17.
18.
The viscosity coefficients for the gaseous states of N2 and O2 and their mixtures are determined at zero and moderately density regimes. The Lennard‐Jones 12–6 (LJ 12–6) potential energy function is used as the initial model potential required y the technique. The interaction potential energies from the inversion procedure reproduce the viscosity commensurate to the best measurements. The initial density dependence of gaseous viscosity coefficient according to the Rainwater‐Friend theory, which was given by Najafi et al., has been considered for pure N2 and pure O2. 相似文献
19.
The perturbed‐chain statistical associating fluid theory (PC‐SAFT) and density‐gradient theory (DGT) were used to construct an equation of state (EOS) for the phase behaviors of carbon dioxide (CO2)‐sulfur dioxide (SO2) binary mixtures. The p‐x diagrams at 263 and 333 K, and the p‐T diagrams corresponding to x=0.8871 and 0.6213 were satisfactorily calculated as compared to the experimental data. With the influence parameters of pure components and the equilibrium bulk properties of mixtures as input, the interfacial properties of CO2‐SO2 binary mixtures in a wide temperature range were predicted, and the influences of temperature, pressure and bulk properties on the surface tension were discussed. 相似文献