Multicomponent Diffusion Revisited: Pair-Mobilities and Consistent Definition of Diffusion Coefficients

2020 ◽  
Author(s):  
Ingo Steinbach ◽  
Julia Kundin ◽  
Katrin Abrahams ◽  
Sergiy V. Divinski
Keyword(s):  
Diffusion Coefficients ◽  
Multicomponent Diffusion ◽  
Definition Of

scholarly journals Experimental study of multicomponent diffusion in low permeable sediments

2019 ◽  
Vol 98 ◽  
pp. 10002
Author(s):  
Vladimir Lekhov ◽  
Alexei Lekhov
Keyword(s):  
Diffusion Coefficients ◽  
Average Length ◽  
Effective Diffusion ◽  
Length Distribution ◽  
Large Degree ◽  
Multicomponent Diffusion ◽  
Distribution Coefficients ◽  
Disposal Site ◽  
Special Equipment ◽  
Permeable Sediments

Diffusion coefficients for Na+ and distribution coefficients for Cs+, Ba2+, Ni2+, CO2+, Sr2+ were measured on low permeable samples (3 cm diameter, average length 7 cm) from the deep disposal site Siberian Chemical Combine (SSC) using the end-diffusion technique. The direction of diffusion was perpendicular to bedding. Special equipment for experiment were designed and constructed. Two types of concentration observation were used. For non-sorbing Na+ in time used EC sensors and length distribution of sorbed elements. The synthetic solution used in the experiments was a model of low-activity contaminant of the SSC, and consist NaNO3 (25 g/l) and nitrate compounds: Cs+, Ba2+, Ni2+, Co2+, Sr2+ (100 mg/l each). The measured values of the effective diffusion coefficients De) for Na+ from 7.60×10-7 to 1.51×10-5 m2/day and volumetric dimensionless distribution coefficients (Kdρ) are: Cs+ from 0.21 to 22.1, Ba2+ from 1.1 to 1.45, Ni2+ from 0.3 to 16.4, Co2+ from 1.98 to 24.7, Sr2+ from 1.9 to 14.3. The values of the diffusion coefficient show a large degree of variability. The diffusion coefficients of non-sorbing Na+ measured in this study are in good agreement with pore-scale diffusion simulation on microtomography data.

Multicomponent diffusion coefficients from microfluidics using Raman microspectroscopy

Lab on a Chip ◽  
2017 ◽  
Vol 17 (16) ◽  
pp. 2768-2776 ◽  
Author(s):  
Christine Peters ◽  
Ludger Wolff ◽  
Sandra Haase ◽  
Julia Thien ◽  
Thorsten Brands ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Multicomponent Diffusion ◽  
High Accuracy ◽  
Raman Microspectroscopy ◽  
Multicomponent Diffusion Coefficients ◽  
Short Time

Microfluidic measurement of multicomponent diffusion coefficients using minimal number of experiments with high accuracy in short time.

Ternary mutual diffusion coefficients of MgCl2 + MgSO4 + H2O and Na2SO4 + MgSO4 + H2O from Taylor dispersion profiles

1991 ◽  
Vol 69 (10) ◽  
pp. 1548-1553 ◽  
Author(s):  
Zhipeng Deng ◽  
Derek G. Leaist
Keyword(s):  
Diffusion Coefficients ◽  
Multicomponent Diffusion ◽  
Taylor Dispersion ◽  
Mutual Diffusion ◽  
Salt Solutions ◽  
Mixed Salt ◽  
Ternary Diffusion ◽  
Peak Broadening ◽  
Ternary Diffusion Coefficients ◽  
Mixed Salt Solutions

The Taylor dispersion (peak-broadening) technique is used to measure the ternary mutual diffusion coefficients of the mixed salt solutions MgCl2 + MgSO4 + H2O and Na2SO4 + MgSO4 + H2O at 25 °C. The dispersion of the solutes is followed by differential refractometry. A simple least-squares procedure is developed to calculate the ternary diffusion coefficients from the refractive index profiles. The coefficients are measured at 0.04, 0.20, or 0.40 mol dm−3 total salt for the molar salt ratios 1:3, 1:1, or 3:1. The measured diffusion coefficients are compared with the limiting values for the completely dissociated salts. Key words: mixed salt solutions, multicomponent diffusion, Taylor dispersion, ternary diffusion coefficients.

An eigenvalue method for determination of multicomponent diffusion coefficients. Application to NaOH + NaCl + H2O mixtures

1985 ◽  
Vol 63 (2) ◽  
pp. 476-482 ◽  
Author(s):  
Derek G. Leaist ◽  
Robert A. Noulty
Keyword(s):  
Diffusion Coefficients ◽  
Binary Data ◽  
Pure Water ◽  
Multicomponent Diffusion ◽  
Diagonal Form ◽  
Inverse Transformation ◽  
Linear Combinations ◽  
Eigenvalue Method ◽  
Multicomponent Diffusion Coefficients

A general method for the determination of multicomponent diffusion coefficients is developed using the algebraic technique of matrix diagonalization. When linear combinations of measurements from several multicomponent diffusion experiments performed with different initial concentration gradients (but with the same final composition) are analyzed as simple binary data, particular combinations may be found that transform the multicomponent diffusion coefficient matrix D to diagonal form and thus yield time-invariant, pseudo-binary diffusion coefficients: the eigenvalues of D. Since the matrix that diagonalizes D is given by the coefficients used to form the linear combinations, D is easily recovered by the inverse transformation. The advantages of the eigenvalue method are briefly discussed. For testing purposes, ternary diffusion coefficients are determined from conductance measurements for dilute aqueous NaOH + NaCl mixtures. Diffusion of NaOH in aqueous NaCl is significantly more rapid than in pure water, and large coupled flows of NaCl are observed. The results are in close agreement with behavior predicted by Onsager–Fuoss theory.

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