Self-diffusion in Liquids

In the special case that A and B are similar in molecular weight, polarity, and so on, the self-diffusion coefficients of pure A and B will be approximately equal to the mutual diffusivity, D g. Second, when A and B are the less mobile and more mobile components, respectively, their self-diffusion coefficients can be used as rough lower and upper bounds of the mutual diffusion coefficient. That is, < D g < Dg g. Third, it is a common means for evaluating diffusion for gases at high pressure. Self-diffusion in liquids has been studied by many [Easteal AIChE]. 30, 641 (1984), Ertl and Dullien, AIChE J. 19, 1215 (1973), and Vadovic and Colver, AIChE J. 18, 1264 (1972)]. 

Following the general trend of looldng for a molecular description of the properties of matter, self-diffusion in liquids has become a key quantity for interpretation and modeling of transport in liquids [5]. Self-diffusion coefficients can be combined with other data, such as viscosities, electrical conductivities, densities, etc., in order to evaluate and improve solvodynamic models such as the Stokes-Einstein type [6-9]. From temperature-dependent measurements, activation energies can be calculated by the Arrhenius or the Vogel-Tamman-Fulcher equation (VTF), in order to evaluate models that treat the diffusion process similarly to diffusion in the solid state with jump or hole models [1, 2, 7]. 

DW McCall, DC Douglas, EW Anderson. Self diffusion in liquids Paraffin hydrocarbons. Phys Fluids 2 87-91, 1959. 

Mass Diffusivity in Liquid Metais and Ailoys. The hard-sphere model of gases works relatively well for self-diffusion in monatomic liquid metals. Several models based on hard-sphere theory exist for predicting the self-diffusivity in liquid metals. One such model utilizes the hard-sphere packing fraction, PF, to determine D (in cm /s) ... 

FREE-VOLUME MODEL FOR SELF-DIFFUSION IN LIQUIDS... 

The NMR technique for measuring self-diffusion in liquids was first reported in 1965390, and its variant for multicomponent mixtures became available with the introduction of the Fourier transform. Wider use had to wait until pulsed field gradients became generally... 

The model of diffusion of hard spheres is applicable to interpret self-diffusion in liquids which behave according to the van der Waals physical interaction model (56). This might be the case for simple dense fluids at high temperature, T Tg, but it is an oversimplified model for the real diffusion of small organic penetrants in polymers. The functional relationships derived in the model of hard-spheres have been reinterpreted over course of the time, leading to a series of more sophisticated free-volume diffusion models. Some of these models are presented briefly below. 

The application of NMR to the study of diffusion in zeolites involves the refinement and extension of methods originally developed to study self diffusion in liquids and low melting solids. The method is restricted to species such as hydrocarbons which contain a sufficiently high density of atoms such as H with unpaired nuclear spins. Authoritative reviews of the application of NMR to the study of adsorbed molecules have been given by Pfeifer(22,23) and only a brief outline is included here. 

Third, it is a common means for evaluating diffusion for gases at high pressure. Self-diffusion in liquids has been studied by many [Easteal, AIChE J. 30, 641 (1984), Ertf and Dullien, AIChE J. 19,1215 (1973), and Vadovic and Colver, AIChE J. 18,1264 (1972)]. 

Norden, A., and A. Lodding Self-Transport, Electro Convection and Effective Self-Diffusion in Liquid Rubidium Metal. Z. Naturforsch. 22 a, 215 (1967). 

Function and the Constant of Self-Diffusion in Liquid Na. Phys. Rev. Letters 16, 300 (1966). 

FlC. 26. Self-diffusion coefficients of methanol (squares) and water (circles) in their binary mixtures sorbed in HZSM-5 for two total loadings 35 mg (H2O + CH3OH) g" (open m-bols) and 50 mg g (filled symbols) at 300 K (725). Comparison with the self-diffusivity in liquid methanol/water mixtures (126,127) dotted line, D(CH30H) dashed lines, D(H20). 

Self-diffusion in liquids (and similar systems) can be measured by the pulsed-field gradient technique. For a hypothetical sample without molccu-... 

K. P. Travis, D. Brown and J. H. R. Clarke, A Molecular Dynamics Study of the Coupling of Torsional Motions to Self-Diffusion in Liquid Hexane J. Chem. Phys. 102(1995)2174-2180. 

The aim of this report is to cover the progress of work in the field of magnetic relaxation and self-diffusion in liquids and gases over a period of twelve months from June 2000 to May 2001, and is a continuation of the report given last year. ... 

Nuclear Spin Relaxation in Liquids and Gases 5 Self-diffusion in Liquids... 

TEMPERATURE AND PRESSURE DEPENDENCE OF SELF-DIFFUSION IN LIQUID ETHANE. 

SPIN REUXATION AND SELF-DIFFUSION IN LIQUID CRYSTALS. 

SELF-DIFFUSION IN LIQUID CARBON DIOXIDE AND PROPANE. 

Naghizadeh, J. and Rice, S. A., Kinetic theory of dense fluids. X. Measurement and interpretation of self-diffusion in liquid Ar, Kr, Xe, and CH4, /. Chem. Phys., 36, 2710,1962. 

Cini-Castagnoli, G. Ricci, F. R (1960). Self-diffusion in liquid argon. J. Chem. Phys., 32, 19-20. 

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