Evaluation of Diffusivity in Dense Polymeric Membranes by Statistical Moment Analysis

0391468 - ÚCHP 2014 RIV NL eng J - Journal Article
Řezníčková Čermáková, Jiřina - Kudrna, Vladimír - Setničková, Kateřina - Uchytil, Petr
Evaluation of Diffusivity in Dense Polymeric Membranes by Statistical Moment Analysis.
Journal of Membrane Science. Roč. 435, 15 MAY (2013), s. 46-51. ISSN 0376-7388. E-ISSN 1873-3123
R&D Projects: GA ČR GA104/09/1165
Institutional support: RVO:67985858
Keywords : diffusion * membranes * transport processes
Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Impact factor: 4.908, year: 2013

A robust procedure to estimate vapor diffusion coefficients from unsteady state measurements is proposed. The permeate flux is measured for a step change in the inlet. The method is based on the interpretation of the normalized permeate flux over time as an integral distribution function. Under the assumption that Fick’s second law is valid, a relation between the first two statistical moments and the diffusion coefficient was found. The resulting expressions are surprisingly short, convenient to use and robust against errors in determining the actual begin time of an experiment. Furthermore, a ratio involving the first two statistical moments yields a constant number. The comparison with the same ratio obtained from experimental data shows whether an unsteady permeation process described above obeys Fick’s second law with constant diffusion coefficient.
Permanent Link: http://hdl.handle.net/11104/0220978