Dilution In Supercritical Carbon Dioxide Research Articles

The retention factors and partial molar volumes of ibuprofen at infinite dilution in supercritical carbon dioxide at T= (308.15, 313.15, 323.15, 333.15, 343.15 and 353.15) K

Here is presented the first experimental data for the infinite dilution partial molar volumes of ibuprofen in supercritical carbon dioxide. The measurements were carried out by supercritical fluid chromatography using chemically bonded polyethylene glycol and carbon dioxide as stationary and mobile phases, respectively. The chromatographic retentions of ibuprofen at infinite dilution in supercritical carbon dioxide were measured at six supercritical isotherms of 308.15, 313.15, 323.15, 333.15, 343.15 and 353.15 K and at a pressure range of 8.50–40.00 MPa. The partial molar volumes were determined from the partial derivatives of the retention factors with respect to the densities and were in the range of −2.364 × 10−3 to 1.680 × 10−4 m3/mol. A reverse behaviour was observed, where the partial molar volumes decreased monotonically with decreasing pressure from positive to negative values in all temperature regions investigated. It was also found that the infinite dilution partial molar volumes showed a sharp decrease near the critical point of carbon dioxide. The experimental partial molar volumes were correlated with isothermal compressibilities and densities of carbon dioxide. The correlation proposed in this study could predict the experimental data with an average absolute relative deviation of 4.6% for 80 data points, which is better than that previously reported in the literature.

Development of a high-pressure set-up for measurements of binary diffusion coefficients in supercritical carbon dioxide.

We present the development of a high-pressure apparatus for measurements of diffusion coefficients in supercritical fluids. The Taylor dispersion method has been adapted to conduct experiments at the pressures up to 25.0 MPa. In order to test the developed set-up, binary diffusion coefficients D at infinite dilution in supercritical carbon dioxide have been measured for a reference system, benzene, at temperatures in the range of 309.50-319.95 K. The effects of flow velocity, number of consecutive injections and absorbance at different wave numbers on the diffusion coefficient have been analysed. The obtained diffusion coefficients are of the order of 10-8 m 2/s and in excellent agreement with the available literature data.

Measurement and correlation of the diffusion coefficients of chromium(III) acetylacetonate at infinite dilution in supercritical carbon dioxide and in liquid ethanol

The diffusion coefficients of chromium(III) acetylacetonate (Cr(acac)3) were measured at infinite dilution in supercritical carbon dioxide and in liquid ethanol. The diffusion measurements in supercritical carbon dioxide were carried out at five different temperatures varying from T=(308.15 to 343.15)K and at pressures up to 40.00MPa by using the chromatographic impulse response (CIR) method. And the measurements in liquid ethanol were also made by the Taylor dispersion method at five temperatures in the range from T=(299.15 to 333.15)K and 0.10MPa. The determined diffusion activation energies in supercritical carbon dioxide were Ea=(22.9–11.2)kJ·mol−1 at p=(13.00–35.00)MPa, respectively, and that in liquid ethanol was 15.9kJ·mol−1 at 0.10MPa. All the diffusion coefficients of Cr(acac)3 in supercritical and in liquid states can be correlated by the hydrodynamic equation as a function of temperature and fluid viscosity with average absolute relative deviation (AARD) of 4.6% over a wide viscosity range from η=(3.036·10−5 to 1.113·10−3)Pa·s for 85 data points.

Diffusion coefficients of metal acetylacetonates in supercritical carbon dioxide

Binary diffusion coefficients, D 12, of the metal acetylacetonates, palladium(II) acetylacetonate and cobalt(III) acetylacetonate, were measured from 308.2 to 343.2 K over the pressure range from 9 to 40 MPa at infinite dilution in supercritical carbon dioxide using the chromatographic impulse response method. The effects of pressure, temperature, density, and viscosity on D 12 values were examined. It was observed that the D 12 values of palladium(II) acetylacetonate and cobalt(III) acetylacetonate were larger than those of lipids with similar molecular weights, such as arachidonic acid and monoolein, respectively. Furthermore, the measured D 12 data of each metal acetylacetonate were well correlated by the hydrodynamic equation D 12/ T as a function of carbon dioxide viscosity.

Diffusion Coefficients of n-Butylbenzene, n-Pentylbenzene, 1-Phenylhexane, 1-Phenyloctane, and 1-Phenyldodecane in Supercritical Carbon Dioxide

Binary diffusion coefficients at infinite dilution in supercritical carbon dioxide, DAB, were measured for five n-alkylbenzenes (n-butylbenzene, n-pentylbenzene, 1-phenylhexane, 1-phenyloctane, and 1-phenyldodecane) by means of the Taylor−Aris technique in a chromatographic apparatus from 313 to 333 K and from 15.0 to 35.0 MPa. The experimental results were correlated with temperature, pressure, solvent viscosity, and solvent density. In the case of temperature dependence, additional measurements were carried out for n-pentylbenzene from 308 to 398 K at 35.0 MPa. As the five solutes are similar molecules, the corresponding states principle of Teja was tested together with the results obtained from several predictive equations based on the Stokes−Einstein formula and on the rough-hard-sphere model.

Limiting Diffusion Coefficients of Ethyl Benzoate, Benzylacetone, and Eugenol in Carbon Dioxide at Supercritical Conditions

The binary diffusions of ethyl benzoate, benzylacetone, and 2-methoxy-4-(2-propenyl)phenol (eugenol) at infinite dilution in supercritical carbon dioxide were measured between (15.0 and 35.0) MPa and in the temperature range of (313 to 333) K by the Taylor−Aris chromatographic method. The measured values were compared with the calculated ones using several predictive formulas. The effect of temperature, pressure, viscosity, and density is also discussed.

Application of the corresponding states principle to the diffusion in CO2

AbstractBinary diffusion coefficients at infinite dilution in supercritical carbon dioxide, DAB, have been measured for the four monohalogenated benzenes (fluorobenzene, chlorobenzene, bromobenzene, and iodobenzene) with the Taylor–Aris technique in a chromatographic apparatus as a function of temperature and pressure. The ranges covered for these two variables were 313–333 K and 15.0–35.0 MPa, respectively. As the four solutes are similar molecules, the corresponding states principle (CSP) has been tested, together with the results of several predictive equations. © 2007 American Institute of Chemical Engineers AIChE J, 2007

Using supercritical fluid chromatography to determine diffusion coefficients of 1,2-diethylbenzene, 1,4-diethylbenzene, 5- tert-butyl- m-xylene and phenylacetylene in supercritical carbon dioxide

The binary diffusion of 1,2-diethylbenzene, 1,4-diethylbenzene, 5- tert-butyl- m-xylene and phenylacetylene at infinite dilution in supercritical carbon dioxide were measured between 15.0 and 35.0 MPa and in the temperature range of 313.16 to 333.16 K by the Taylor–Aris chromatographic method. The effect of temperature, pressure, viscosity and density was discussed. In the case of temperature dependence, additional measurements were done for 5- tert-butyl- m-xylene from 308.16 to 398.16 K at 35.0 MPa. The measured diffusivities of the four solutes were compared with the calculated ones by several predictive formulas.

Molecular diffusion coefficients of phenylmethanol, 1-phenylethanol, 2-phenylethanol, 2-phenyl-1-propanol, and 3-phenyl-1-propanol in supercritical carbon dioxide

The Taylor–Aris chromatographic technique was employed for the determination of the diffusion coefficients of phenylmethanol, 1-phenylethanol, 2-phenylethanol, 2-phenyl-1-propanol, and 3-phenyl-1-propanol at infinite dilution in supercritical carbon dioxide from 313.16 to 333.16 K and pressures between 15.0 and 35.0 MPa. Diffusivities were correlated with temperature, pressure, solvent density and solvent viscosity, and 12 predictive equations were compared with experimental data: Wilke–Chang, Lusis–Ratcliff, Tyn–Calus, Kooijman, Lai–Tan, Catchpole–King, Eaton–Akgerman, He, He–Yu, Liu–Silva–Macedo, Dariva–Coelho–Oliveira, and Rah–Kwak–Eu–Laffleur. Considerations regarding the diffusion coefficients of the isomers were also made.

Diffusion coefficients of 2-fluoroanisole, 2-bromoanisole, allylbenzene and 1,3-divinylbenzene at infinite dilution in supercritical carbon dioxide

The Taylor–Aris chromatographic technique was employed for the determination of diffusion coefficients of 2-fluoroanisole, 2-bromoanisole, allylbenzene and 1,3-divinylbenzene at infinite dilution in supercritical carbon dioxide from 313.16 to 333.16 K and pressures between 15 and 35 MPa. As expected, the diffusivities rise when temperature increases and pressure decreases. Numerous predictive equations are compared with experimental data: Lai–Tan, Liu–Ruckenstein cluster formula, Woerlee, Hippler–Schubert–Troe, Catchpole–King, Eaton–Akgerman, He, He–Yu, Liu–Silva–Macedo, Funazukuri and coworkers, Dariva–Coelho–Oliveira, Zhu–Lu–Zhou–Wang–Shi and the Liu–Ruckenstein RHS formula. The equations of He, He–Yu and Catchpole–King are the best of all, but cannot be used in the whole range of temperatures and solvent densities.

Solute Diffusion in Supercritical Solvents – Diffusion Coefficients D 12 ∞ and Diffusion–Viscosity Relationship for the Aromatic Model Solute Biphenyl in Carbon Dioxide

Abstract The temperature and density dependence of the mutual diffusion coefficient D 12 ∞ of biphenyl at infinite dilution in supercritical carbon dioxide has been measured by the Taylor dispersion method at several temperatures from 309 K to 331 K and at pressures between about 8 MPa and 20 MPa, corresponding to densities from about 500 kg m−3 to 850 kg m−3. The observed diffusion coefficients are of the order of 10−8 m2 s−1. They decrease about linearly with increasing density and increase slightly with increasing temperature. The experimental data show a density and temperature dependence of the quantity D 12 ∞η/T, indicating a breakdown of the Stokes–Einstein relation. The use of empirical fractional power laws for describing the self-diffusion–viscosity relationship is discussed.

Binary diffusion coefficient, partition ratio, and partial molar volume for docosahexaenoic acid, eicosapentaenoic acid and α-linolenic acid at infinite dilution in supercritical carbon dioxide

A tracer response technique with a poly(ethylene glycol) coated capillary column was employed to measure binary diffusion coefficient and partition ratio for the ω3 group of long chain unsaturated fatty acids such as docosahexaenoic acid, eicosapentaenoic acid and α-linolenic acid at infinite dilution in supercritical (SC) carbon dioxide at temperatures from 308.15 to 343.15 K and pressures from 9 to 30 MPa. The binary diffusion coefficients for each solute were expressed with the Schmidt number correlation as well as the correlation with temperature and CO 2 viscosity. The partition ratios were correlated with temperature and CO 2 density. Moreover, the partial molar volumes were obtained from the partition ratios for each solute.

Partial Molar Volumes of Methanol and Ethanol at Infinite Dilution in Supercritical Carbon Dioxide.

ln the present study, partial molar volumes of methanol at 313.15K and ethanol at 308.15K at infinite dilution in supercritical carbon dioxide were measured between 7MPa and 10MPa. Partial molar volumes of alcohol at infinite dilution were evaluated with the molar volume of pure carbon dioxide and the one of the homogeneous fluid made of carbon dioxide and a small amount of alcohol at the same temperature and pressure. The experimental data obtained were correlated with the Soave-Redlich-Kwong equation of state.

Investigation of equilibrium and kinetic parameters for air stripping of volatile and semi volatile organic contaminants from soil by dynamic experiments

The Taylor–Aris chromatographic technique was employed for the determination of diffusion coefficients of 2-fluoroanisole, 2-bromoanisole, allylbenzene and 1,3-divinylbenzene at infinite dilution in supercritical carbon dioxide from 313.16 to 333.16 K and pressures between 15 and 35 MPa. As expected, the diffusivities rise when temperature increases and pressure decreases. Numerous predictive equations are compared with experimental data: Lai–Tan, Liu–Ruckenstein cluster formula, Woerlee, Hippler–Schubert–Troe, Catchpole–King, Eaton–Akgerman, He, He–Yu, Liu–Silva–Macedo, Funazukuri and coworkers, Dariva–Coelho–Oliveira, Zhu–Lu–Zhou–Wang–Shi and the Liu–Ruckenstein RHS formula. The equations of He, He–Yu and Catchpole–King are the best of all, but cannot be used in the whole range of temperatures and solvent densities.