Self-Diffusion Coefficients of Methane or Ethane Mixtures with Hydrocarbons at High Pressure by NMR

1996 ◽  
Vol 41 (3) ◽  
pp. 598-603 ◽  
Author(s):  
M. Helbæk ◽  
B. Hafskjold ◽  
D. K. Dysthe ◽  
G. H. Sørland
Keyword(s):  
High Pressure ◽  
Diffusion Coefficients ◽  
Self Diffusion

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf2N] at high pressure

2015 ◽  
Vol 17 (37) ◽  
pp. 23977-23993 ◽  
Author(s):  
Kenneth R. Harris ◽  
Mitsuhiro Kanakubo
Keyword(s):  
High Pressure ◽  
Ionic Liquid ◽  
Transport Properties ◽  
Diffusion Coefficients ◽  
Cross Correlation ◽  
Diffusion Velocity ◽  
Self Diffusion ◽  
Scaling Parameters ◽  
Resistance Coefficients ◽  
Viscosity Dependence

Distinct diffusion coefficients for 1-alkyl-3-imidazolium [Tf2N] salts show very similar viscosity dependence; thermodynamic scaling parameters for the reduced transport properties are equal.

scholarly journals A NMR Spin-Echo Study of Diffusion in Molten Salts

2004 ◽  
Vol 59 (1-2) ◽  
pp. 51-58 ◽  
Author(s):  
Günter Palmer ◽  
Joachim Richter ◽  
Manfred D. Zeidler
Keyword(s):  
High Pressure ◽  
Titanium Alloy ◽  
Diffusion Coefficients ◽  
High Frequency ◽  
Molten Salts ◽  
Pressure Range ◽  
Spin Echo ◽  
Ambient Pressure ◽  
Pressure Probe ◽  
Self Diffusion

Pressure-dependent measurements of the cationic self-diffusion coefficients of molten (Na, Li)NO3 were carried out at 613 K. The pressure range lies between ambient pressure and 200 MPa. A new high-pressure probe, operating with heating coils, was constructed from titanium alloy. The temperature difference across the probe could be confined to 2.5 K. By use of a switchable high-frequency coil the nuclei lithium and sodium could be measured in succession within the same sample. The activation volumes are composition-dependent and range from 5 to 9 cm3mol−1.

scholarly journals An NMR Spin-Echo Study of Diffusion in a Room-Temperature Molten Salt

2004 ◽  
Vol 59 (1-2) ◽  
pp. 59-63 ◽  
Author(s):  
Günter Palmer ◽  
Joachim Richter ◽  
Manfred D. Zeidler
Keyword(s):  
High Pressure ◽  
Molten Salt ◽  
Diffusion Coefficients ◽  
Pressure Range ◽  
Room Temperature ◽  
Spin Echo ◽  
Ambient Pressure ◽  
The Self ◽  
Pressure Probe ◽  
Self Diffusion

Pressure-dependent measurements of self-diffusion in the room-temperature molten salt (RTMS) N,N-butylmethylimidazoliumhexafluorophosphate were carried out at 298 and 308 K. The pressure range lied between ambient pressure and 300 MPa. In addition, methanolic solutions of this RTMS were investigated at ambient pressure. The self-diffusion coefficients of both components are reported as functions of concentration and temperature in the range 293 - 313 K. A modified version of a recently published high-pressure probe is described.

scholarly journals Theoretical Modelling of Ion Exchange Processes in Glass: Advances and Challenges

2021 ◽  
Vol 11 (11) ◽  
pp. 5070
Author(s):  
Xesús Prieto-Blanco ◽  
Carlos Montero-Orille
Keyword(s):  
Ion Exchange ◽  
Diffusion Coefficients ◽  
Molten Salts ◽  
Theoretical Modelling ◽  
Copper Films ◽  
Theoretical Frameworks ◽  
Self Diffusion ◽  
Exchange Processes ◽  
The One ◽  
Made In

In the last few years, some advances have been made in the theoretical modelling of ion exchange processes in glass. On the one hand, the equations that describe the evolution of the cation concentration were rewritten in a more rigorous manner. This was made into two theoretical frameworks. In the first one, the self-diffusion coefficients were assumed to be constant, whereas, in the second one, a more realistic cation behaviour was considered by taking into account the so-called mixed ion effect. Along with these equations, the boundary conditions for the usual ion exchange processes from molten salts, silver and copper films and metallic cathodes were accordingly established. On the other hand, the modelling of some ion exchange processes that have attracted a great deal of attention in recent years, including glass poling, electro-diffusion of multivalent metals and the formation/dissolution of silver nanoparticles, has been addressed. In such processes, the usual approximations that are made in ion exchange modelling are not always valid. An overview of the progress made and the remaining challenges in the modelling of these unique processes is provided at the end of this review.

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.

scholarly journals Effect of Modification on the Fluid Diffusion Coefficient in Silica Nanochannels

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4030
Author(s):  
Gengbiao Chen ◽  
Zhiwen Liu
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Surface Effect ◽  
Bulk Water ◽  
Self Diffusion ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Chain Lengths ◽  
Fluid Diffusion ◽  
Self Diffusion Coefficient

The diffusion behavior of fluid water in nanochannels with hydroxylation of silica gel and silanization of different modified chain lengths was simulated by the equilibrium molecular dynamics method. The diffusion coefficient of fluid water was calculated by the Einstein method and the Green–Kubo method, so as to analyze the change rule between the modification degree of nanochannels and the diffusion coefficient of fluid water. The results showed that the diffusion coefficient of fluid water increased with the length of the modified chain. The average diffusion coefficient of fluid water in the hydroxylated nanochannels was 8.01% of the bulk water diffusion coefficient, and the diffusion coefficients of fluid water in the –(CH2)3CH3, –(CH2)7CH3, and –(CH2)11CH3 nanochannels were 44.10%, 49.72%, and 53.80% of the diffusion coefficients of bulk water, respectively. In the above four wall characteristic models, the diffusion coefficients in the z direction were smaller than those in the other directions. However, with an increase in the silylation degree, the increased self-diffusion coefficient due to the surface effect could basically offset the decreased self-diffusion coefficient owing to the scale effect. In the four nanochannels, when the local diffusion coefficient of fluid water was in the range of 8 Å close to the wall, Dz was greater than Dxy, and beyond the range of 8 Å of the wall, the Dz was smaller than Dxy.

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