Multicomponent diffusion in dilute solutions of mixed electrolytes

1980 ◽  
Vol 33 (9) ◽  
pp. 1869 ◽  
Author(s):  
DG Leaist ◽  
PA Lyons
Keyword(s):  
Diffusion Coefficients ◽  
Transport Coefficients ◽  
Ionic Conductivities ◽  
Multicomponent Diffusion ◽  
Mixed Electrolytes ◽  
Dilute Solutions ◽  
Ternary Diffusion ◽  
Mixed Electrolyte ◽  
Coupled Diffusion ◽  
Phenomenological Coefficients

The Onsager-Fuoss theory of ion transport can be used to study multicomponent diffusion in dilute solutions of mixed electrolytes. Precise Lij phenomenological coefficients can be calculated from a knowledge of the solvent properties and limiting ionic conductivities. If activity coefficients for dilute mixed electrolyte systems are available, precise multicomponent diffusion coefficients can also be calculated. Explicit equations are given for calculating both sets of transport coefficients. The equations apply to systems containing an arbitrary number of strong electrolytes and are valid at low total salt concentrations. To illustrate the use of the equations, ternary diffusion in a few aqueous systems is examined in detail. Aqueous mixed electrolyte systems containing H+ exhibit strongly coupled diffusion and highly variable diffusion coefficients. A modified Harned conductimetric experiment is described for the determination of ternary diffusion coefficients in dilute solutions. Results for the system HCl- KCl-H2O are in good agreement with theoretical predictions.

Concentration Oscillations During Diffusion With Slow First-Order Chemical Reaction in Aqueous Solutions of trans-Dichloro-bis(ethane-1,2-diamine)cobalt(III) Chloride, trans-[Co(en)2Cl2]Cl

1988 ◽  
Vol 41 (4) ◽  
pp. 469 ◽  
Author(s):  
DG Leaist
Keyword(s):  
Aqueous Solutions ◽  
Chemical Reaction ◽  
Diffusion Coefficients ◽  
Potassium Acetate ◽  
Potassium Sulfate ◽  
Rate Equations ◽  
Ternary Diffusion ◽  
Mixed Electrolyte ◽  
First Order ◽  
First Order Chemical Reaction

The rate equations for diffusion and chemical reaction have been solved for isothermal diffusion with the first-order reactionA → Bin stirred diaphragm cells. Provided pseudo-steady-state conditions are established in the diaphragms, the concentration differences across the diaphragm for the reactant and product are predicted to show damped oscillations in time for certain values of the solute diffusivities. Diffusion coefficients have been determined for aqueous solutions of trans-dichlorobis (ethane-1,2-diamine)cobalt(III) chloride in which the 1 : 1 salt slowly converts into a 1:2 salt through the reaction [Co(en)2Cl2]+ + Cl - → [Co(en)2Cl]2+ +2Cl- with k = 3.6×10-5 s-1 at 25°C. Supplementary ternary diffusion coefficients have been determined for aqueous solutions of potassium acetate + potassium sulfate, a ternary mixed electrolyte with ionic mobilities similar to those of the aqueous cobalt salts.

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.

scholarly journals Coupled transport of iodide ions during interdiffusion of aqueous HCl and NaOH

1987 ◽  
Vol 65 (10) ◽  
pp. 2489-2494 ◽  
Author(s):  
Derek G. Leaist
Keyword(s):  
Diffusion Coefficients ◽  
Transport Coefficients ◽  
Multicomponent Diffusion ◽  
Coupled Transport ◽  
Iodide Ions ◽  
Multicomponent Transport ◽  
Transport Of Ions ◽  
Acids And Bases ◽  
Strong Acids

Stokes diaphragm cells have been used to study multicomponent diffusion in aqueous HCl–NaOH–NaI mixtures at 25 °C. The nine quaternary diffusion coefficients for the mixture containing 0.025 mol L−1 of each electrolyte are reported. The measured coefficients are used to analyze coupled transport of iodide ions generated by interdiffusion of aqueous HCl and NaOH. The analysis shows that the gradient in concentration of NaOH is twice as effective at producing flow of iodide ions relative to the HCl gradient, and that the NaI gradient substantially alters the rates of diffusion of HCl and NaOH components. Equations are developed for predicting multicomponent transport coefficients that describe coupled transport of ions driven by interdiffusion of strong acids and bases.

scholarly journals Thermodynamic Theory of Diffusion and Thermodiffusion Coefficients in Multicomponent Mixtures

2020 ◽  
Vol 45 (4) ◽  
pp. 343-372
Author(s):  
Alexander A. Shapiro
Keyword(s):  
Diffusion Coefficients ◽  
Symmetry Property ◽  
Transport Coefficients ◽  
Thermodynamic Theory ◽  
Statistical Fluctuation ◽  
Multicomponent Mixtures ◽  
Practical Applications ◽  
Chemical Potentials ◽  
Onsager Symmetry ◽  
Phenomenological Coefficients

AbstractTransport coefficients (like diffusion and thermodiffusion) are the key parameters to be studied in non-equilibrium thermodynamics. For practical applications, it is important to predict them based on the thermodynamic parameters of a mixture under study: pressure, temperature, composition, and thermodynamic functions, like enthalpies or chemical potentials. The current study develops a thermodynamic framework for such prediction. The theory is based on a system of physically interpretable postulates; in this respect, it is better grounded theoretically than the previously suggested models for diffusion and thermodiffusion coefficients. In fact, it translates onto the thermodynamic language of the previously developed model for the transport properties based on the statistical fluctuation theory. Many statements of the previously developed model are simplified and amplified, and the derivation is made transparent and ready for further applications. The n(n+1)/2 independent Onsager coefficients are reduced to 2n+1 determining parameters: the emission functions and the penetration lengths. The transport coefficients are expressed in terms of these parameters. These expressions are much simplified based on the Onsager symmetry property for the phenomenological coefficients. The model is verified by comparison with the known expressions for the diffusion coefficients that were previously considered in the literature.

Interdiffusion of acids and bases•HCl and NaOH in aqueous solution

1986 ◽  
Vol 64 (5) ◽  
pp. 1007-1011 ◽  
Author(s):  
Derek G. Leaist ◽  
Betty Wiens
Keyword(s):  
Aqueous Solution ◽  
Diffusion Coefficients ◽  
Diffusion Path ◽  
Ternary Diffusion ◽  
Analytic Approximations ◽  
Coupled Diffusion ◽  
Ternary Diffusion Coefficients ◽  
Acids And Bases ◽  
Rich Mixtures ◽  
Diffusion Properties

Stokes magnetically stirred diaphragm cells have been used to measure interdiffusion of hydrochloric acid and sodium hydroxide in aqueous solution at 25 °C. Expressions are developed to estimate ternary diffusion coefficients for these mixtures. The analysis reveals sharp discontinuities between the diffusion properties of HCl-rich and NaOH-rich mixtures. Although the diffusion coefficients are sensitive to concentration, accurate analytic approximations for rates of interdiffusion can be obtained by averaging coefficients along the diffusion path. When HCl and NaOH interdiffuse, proton-coupled and hydroxide-coupled diffusion operating simultaneously on opposite sides of the diffusion boundary lead to rapid diffusion of inert Na+ and Cl− species.

Transport coefficients of oligo- and poly(dimethylsiloxanes) in dilute solutions. The draining effect

1993 ◽  
Vol 26 (10) ◽  
pp. 2566-2574 ◽  
Author(s):  
Takeshi Yamada ◽  
Hitoshi Koyama ◽  
Takenao Yoshizaki ◽  
Yoshiyuki Einaga ◽  
Hiromi Yamakawa
Keyword(s):  
Transport Coefficients ◽  
Dilute Solutions

scholarly journals Self-Diffusion Coefficients of Methane/n-Hexane Mixtures at High Pressures: An Evaluation of the Finite-Size Effect and a Comparison of Force Fields

2019 ◽  
Author(s):  
Thiago José Pinheiro dos Santos ◽  
Charlles Abreu ◽  
Bruno Horta ◽  
Frederico W. Tavares
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
Force Fields ◽  
Transport Coefficients ◽  
Finite Size ◽  
Finite Size Effect ◽  
Self Diffusion ◽  
Analytical Correction ◽  
Dynamics Simulations

Mass transport coefficients play an important role in process design and in compositional grading of oil reservoirs. As experimental measurements of these properties can be costly and hazardous, Molecular Dynamics simulations emerge as an alternative approach. In this work, we used Molecular Dynamics to calculate the self-diffusion coefficients of methane/n-hexane mixtures at different conditions, in both liquid and supercritical phases. We evaluated how the finite box size and the choice of the force field affect the calculated properties at high pressures. Results show a strong dependency between self-diffusion and the simulation box size. The Yeh-Hummer analytical correction [J. Phys. Chem. B, 108, 15873 (2004)] can attenuate this effect, but sometimes makes the results depart from experimental data due to issues concerning the force fields. We have also found that different all-atom and united-atom models can produce biased results due to caging effects and to different dihedral configurations of the n-alkane.

Stress Generation during Grain Boundary Interdiffusion

2011 ◽  
Vol 309-310 ◽  
pp. 19-28 ◽  
Author(s):  
Leonid Klinger ◽  
Eugen Rabkin
Keyword(s):  
Stress Field ◽  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Concentration Distribution ◽  
Boundary Diffusion ◽  
Elastic Stress ◽  
Bulk Diffusion ◽  
Stress Generation ◽  
Additional Material ◽  
Coupled Diffusion

A grain boundary interdiffusion in a semi-infinite bicrystal under the conditions of negligible bulk diffusion is considered. We show that the inequality of intrinsic grain boundary diffusion coefficients of the two components leads to plating out of additional material at the grain boundary in the form of extra material wedge, which generates an elastic stress field in the vicinity of the grain boundary. We solved a coupled diffusion/elasticity problem and determined the time-dependent stress field and concentration distribution in the vicinity of the grain boundary.

Sign in / Sign up

Export Citation Format

Share Document