p, T-Dependence of Self Diffusion in Mixtures of Hexane/Ethanol and Hexane/Dimethylether

1995 ◽  
Vol 50 (2-3) ◽  
pp. 149-154 ◽  
Author(s):  
A. Heinrich-Schramm ◽  
W. E. Price ◽  
H.-D. Lüdemann
Keyword(s):  
Hydrogen Bonding ◽  
Qualitative Analysis ◽  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
Low Temperatures ◽  
The Self ◽  
Slight Effect ◽  
Self Diffusion ◽  
Dipole Interactions ◽  
Significant Difference

Abstract Self-diffusion in ethanol/hexane and dimethylether/hexane mixtures of various compositions has been measured at 215-350 K and up to 200 MPa. Qualitative analysis of the results indicates that, as expected, hydrogen bonding retards the self-diffusion of ethanol in the mixture, especially at the low temperatures. Dimethylether shows a slight effect of dipole-dipole interactions on the self-diffu­sion, as seen by a higher ΔE* value than for the alkane. However there is no significant difference in the pressure dependence for both mixtures. This is shown by considering the ratio of the two diffusion coefficients, which suggests that, contrary to what is observed for pure alcohols, pressure has little effect upon the hydrogen bonding of ethanol in the mixture. In additon, there is surprisingly little concentration dependence on the ratios for either mixture.

Composition and Pressure Dependence of the Diffusion Coefficients in Binary Liquid Alloys

2010 ◽  
Vol 297-301 ◽  
pp. 1371-1376
Author(s):  
Dezső L. Beke
Keyword(s):  
Activation Energy ◽  
Melting Point ◽  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
The Self ◽  
Interatomic Potentials ◽  
Liquid Alloys ◽  
Diffusion In Solids ◽  
Self Diffusion ◽  
Binary Liquid

There are a number of well-known empirical relations for diffusion in solids. For example the proportionality between the self-diffusion activation energy and melting point or between the entropy of the diffusion and the ratio of activation energy and the melting point (Zener rule) are perhaps the best known ‘rules of thumb’. We have shown earlier in our Laboratory, that these relations are direct consequences of the similarity of interatomic potentials seen by ions in solids. On the basis of this, similar relations were extended for impurity and self diffusion in binary solid alloys. In this paper, results for binary liquid mixtures will be reviewed. First a minimum derivation of the temperature dependence of the self-diffusion coefficient, D, is presented (minimum derivation in the sense that it states only that the reduced (dimensionless) D should be a universal function of the reduced temperature), using the similarity of interatomic potentials and dimensional analysis. Then the extension of this relation for determination of the pressure and composition dependence of the self-diffusion coefficients is described using pressure and composition dependent scaling parameters (melting point, atomic volume and mass). The obtained universal form (valid for binary liquid alloys) is very useful for the estimation of the temperature, composition and pressure dependence of the self-diffusion coefficients. Finally, the relation for the ratio of the impurity and self-diffusion coefficients is derived.

Pressure Dependence of the Melting and Self Diffusion in 2,2-dimethylpropane, 2,2-dimethylpropionitrile, and 2-methylpropanol-2

1984 ◽  
Vol 39 (8) ◽  
pp. 800-806 ◽  
Author(s):  
M. Woznyj ◽  
F. X. Prielmeier ◽  
H.-D. Lüdemann
Keyword(s):  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
The Self ◽  
Pressure Curve ◽  
Hard Sphere Model ◽  
Sphere Model ◽  
Melting Pressure ◽  
Self Diffusion ◽  
Straight Lines

The melting pressure curves of 2,2-dimethylpropane, 2,2-dimethylpropionitrile and 2-methylpropanol- 2 and the pressure dependence of the hex ⇔ fee transition of 2,2-dimethylpropane have been determined in the pressure range between 0.1 and 200 MPa. The self diffusion coefficients D in the liquid state of the three compounds have been determined as function of pressure (pmax ≧ 120 MPa) from the melting pressure curve up to ca. 450 K. At high temperatures and high pressures the self diffusion coefficients of the three compounds become rather similar. The influence of the hydroxylgroup upon the diffusivity of (CH3)3COD is most clearly seen at the lowest temperatures. The isobars of C(CH3)4 and (CH3)3CCN are straight lines with identical slopes. For (CH3)3COD all isobars show a curvature. From the data in the Arrhenius representation activation volumes and activation energies are derived. For C (CH3)4 the density dependence of D can be described with the rough hard sphere model.

scholarly journals Aggregation Behavior of 6-Isocassine and N-Methyl-6-Isocassine: Insights into the Biological Mode of Action of Lipid Alkaloids

2016 ◽  
Vol 11 (11) ◽  
pp. 1934578X1601101
Author(s):  
Luis Reina ◽  
Gualberto Bottini ◽  
Zohra Bennadji ◽  
Vittorio Vinciguerra ◽  
Fernando Ferreira ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Diffusion Coefficients ◽  
Mode Of Action ◽  
Aggregation Behavior ◽  
The Self ◽  
Self Diffusion ◽  
And Diffusion

The aggregation behavior of 6-isocassine and N-methyl-6-isocassine, two piperidin-3-ol alkaloids isolated respectively from the barks of Prosopis nigra and P. affinis, was investigated using a combination of NOE experiments and diffusion measurements in solvents of varying polarity and hydrogen bonding capacity. While the NOE enhancements for N-methyl-6-isocassine are positive, regardless of the solvent, those for 6-isocassine shift from negative to positive when going from chloroform- d to methanol- d 4 solution. In addition, despite the self-diffusion coefficients of both compounds being virtually identical in methanol- d 4, N-methyl-6-isocassine diffuses nearly twice as fast as the non-methylated alkaloid in chloroform- d. The changes in rotational and translational dynamics observed between solvents for 6-isocassine suggest that the molecule forms dimeric head-to-head aggregates in non-polar aprotic environments, a behavior that could help explain the biological mode of action that has been proposed for this type of alkaloids.

scholarly journals Self-Diffusion Coefficients, Aggregation Numbers and the Range of Existence of Spherical Micelles of Oxyethylated Alkylphenols

2021 ◽  
Author(s):  
Victor P. Arkhipov ◽  
Natalia A. Kuzina ◽  
Andrei Filippov
Keyword(s):  
Aqueous Solutions ◽  
Diffusion Coefficients ◽  
The Self ◽  
Self Diffusion ◽  
Aggregation Numbers ◽  
Temperature Ranges ◽  
Spherical Micelles ◽  
Limiting Values

AbstractAggregation numbers were calculated based on measurements of the self-diffusion coefficients, the effective hydrodynamic radii of micelles and aggregates of oxyethylated alkylphenols in aqueous solutions. On the assumption that the radii of spherical micelles are equal to the lengths of fully extended neonol molecules, the limiting values of aggregation numbers corresponding to spherically shaped neonol micelles were calculated. The concentration and temperature ranges under which spherical micelles of neonols are formed were determined.

Concentration dependence of the self-diffusion coefficients of water in electrolyte solutions

1974 ◽  
Vol 14 (6) ◽  
pp. 915-918
Author(s):  
A. M. Sazonov ◽  
V. M. Olevskii ◽  
A. B. Porai-Koshits ◽  
V. N. Skobolev ◽  
G. A. Shmuilovich
Keyword(s):  
Concentration Dependence ◽  
Diffusion Coefficients ◽  
Electrolyte Solutions ◽  
The Self ◽  
Self Diffusion

scholarly journals Investigation of the Self-Diffusion Coefficients of Trivalent Gd3+ in aqueous solutions: The Effect of Hydrolysis and nitrate ion association

2012 ◽  
Vol 1 (6) ◽  
pp. 334-346 ◽  
Author(s):  
Rafik Besbes ◽  
Noureddine Ouerfelli ◽  
Manef Abderabba ◽  
Patric Lindqvist-Reis ◽  
Habib Latrous
Keyword(s):  
Aqueous Solutions ◽  
Diffusion Coefficients ◽  
Ion Association ◽  
The Self ◽  
Nitrate Ion ◽  
Self Diffusion

Self-Diffusion of Sodium, Chloride and Iodide Ions in Methanol-Water Mixture

1986 ◽  
Vol 41 (7) ◽  
pp. 939-943 ◽  
Author(s):  
E. Hawlicka
Keyword(s):  
Sodium Chloride ◽  
Diffusion Coefficients ◽  
Solvent Composition ◽  
The Self ◽  
Water Mixture ◽  
Preferential Hydration ◽  
Water Solutions ◽  
Iodide Ions ◽  
Self Diffusion

The self-diffusion coefficients of Na+, Cl- and I- in methanol-water solutions at 35 ± 0.01 °C have been measured in their dependence on the salt molarity in the range 1 · 10-4- 1 · 10-2 mol dm -3. The ionic self-diffusion coefficients in infinitely diluted solutions have been computed. The influence of the solvent composition on the solvation of the ions is discussed. A preferential hydration of Na+, Cl- and I- ions in water-methanol mixtures has been found.

c , T-Dependence of the Self Diffusion in Concentrated Aqueous Sucrose Solutions

1994 ◽  
Vol 49 (3-4) ◽  
pp. 258-264 ◽  
Author(s):  
D. Girlich ◽  
H.-D. Lüdemann ◽  
C. Buttersack ◽  
K. Buchholz
Keyword(s):  
Field Gradient ◽  
Concentration Dependence ◽  
Diffusion Coefficients ◽  
The Self ◽  
Water Molecules ◽  
Pulsed Field Gradient Nmr ◽  
Pulsed Field ◽  
Self Diffusion ◽  
Sucrose Solutions ◽  
Wide Range

The self diffusion coefficients D of the water molecules and of sucrose have been determined by the pulsed field gradient NMR technique over a wide range of temperatures and concentrations (cmax: 70% w/w suc.). All temperature dependencies can be fitted to a Vogel- Tammann-Fulcher equation. The isothermic concentration dependence of D for the sucrose is given by a simple exponential concentration dependence

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