scholarly journals Diffusion in Binary Aqueous Solutions of Alcohols by Molecular Simulation

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 947 ◽  
Author(s):  
Alexander Klinov ◽  
Ivan Anashkin
Keyword(s):  
Experimental Data ◽  
Aqueous Solutions ◽  
Diffusion Coefficients ◽  
Force Fields ◽  
Fickian Diffusion ◽  
Intermolecular Potential ◽  
Thermodynamic Factor ◽  
Self Diffusion ◽  
Temperature Dependences ◽  
Transport Diffusion

Based on the molecular dynamics method, the calculations for diffusion coefficients were carried out in binary aqueous solutions of three alcohols: ethanol, isopropanol, and tert-butanol. The intermolecular potential TIP4P/2005 was used for water; and five force fields were analyzed for the alcohols. The force fields providing the best accuracy of calculation were identified based on a comparison of the calculated self-diffusion coefficients of pure alcohols with the experimental data for internal (Einstein) diffusion coefficients of alcohols in solutions. The temperature and concentration dependences of the interdiffusion coefficients were determined using Darken’s Equation. Transport (Fickian) diffusion coefficients were calculated using a thermodynamic factor determined by the non-random two-liquid (NRTL) and Willson models. It was demonstrated that for adequate reproduction of the experimental data when calculating the transport diffusion coefficients, the thermodynamic factor has to be 0.64. Simple approximations were obtained, providing satisfactory accuracy in calculating the concentration and temperature dependences of the transport diffusion coefficients in the studied mixtures.

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.

Generalized concentration dependence of globular protein self-diffusion coefficients in aqueous solutions

Biopolymers ◽  
2002 ◽  
Vol 63 (2) ◽  
pp. 132-140 ◽  
Author(s):  
Irina V. Nesmelova ◽  
Vladimir D. Skirda ◽  
Vladimir D. Fedotov
Keyword(s):  
Aqueous Solutions ◽  
Concentration Dependence ◽  
Diffusion Coefficients ◽  
Globular Protein ◽  
Self Diffusion

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.

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

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.

Diffusion of Herbicides to Seed

Weed Science ◽  
1971 ◽  
Vol 19 (2) ◽  
pp. 128-132 ◽  
Author(s):  
H. D. Scott ◽  
R. E. Phillips
Keyword(s):  
Experimental Data ◽  
Glycine Max ◽  
Theoretical Result ◽  
Aqueous Solutions ◽  
Plant Species ◽  
Seed Size ◽  
Diffusion Coefficients ◽  
Experimental Error ◽  
Limiting Factor

Prior to germination, seed of some plant species either adsorb or absorb some herbicides applied to the soil. Equations were developed describing the concentration of the herbicide expected in the seed both when diffusion of the herbicide in the soil is the limiting factor and when diffusion of the herbicide within the seed is the limiting factor. Expected concentrations of the herbicide in the seed were presented for combinations of three seed radii (seed were assumed to be spheres) five diffusion times, and five diffusion coefficients. The calculated concentrations of the herbicide in the seed in ppm increased as seed size or radii decreased. This theoretical result was consistent with experimental data and potentially explains why some large-seeded plant species are difficult to control with the use of herbicides. The equation developed for a perfect “sink” predicted within experimental error the concentration of isopropylm-chlorocarbanilate (chlorpropham) absorbed by soybean (Glycine max(L.) Merr.) seed from aqueous solutions of chlorpropham.

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