Premium
Influence of the Non‐Perfect Step Input Concentration at the Feed Side of the Membrane Surface on the Diffusion Coefficient Evaluation
Author(s) -
Cermakova Jirina,
Fialova Katerina,
Petrychkovych Roman,
Kudrna Vladimir,
Uchytil Petr
Publication year - 2006
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.200500073
Subject(s) - permeation , diffusion , membrane , chemistry , diffusion process , effective diffusion coefficient , steady state (chemistry) , function (biology) , polymer , thermodynamics , upstream (networking) , process (computing) , mechanics , computer science , physics , organic chemistry , medicine , computer network , biochemistry , operating system , knowledge management , innovation diffusion , radiology , evolutionary biology , biology , magnetic resonance imaging
Summary: Vapor diffusion coefficients in polymeric membranes were evaluated from dynamic permeation experiments. A membrane separated the diffusion cell into two parts – upstream and downstream. At the start of the experiment the concentration change in the upstream part (feed side) was made by substituting the input stream of pure nitrogen by the stream of permeant vapors. The solution of the Fick's second law with the step input concentration function is used for the evaluation of diffusion coefficients. The realization of the step input function can be difficult and its imperfection can negatively influence the evaluation process. This contribution deals with the description of the experimentally obtained input function and the study of its influence on evaluated values of diffusion coefficients. The mathematical model, which includes the non‐perfect step input concentration function and the transport through a polymer was developed. The results of this study enable the estimation of diffusion coefficient evaluation errors as dependence on the experimental arrangements and on the membrane transport properties.Diffusion apparatus for measurement of the steady‐state permeation process.