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Feed Side (feed + side)

Distribution by Scientific Domains
Polymers and Materials Science75%

Selected Abstracts

Influence of the Non-Perfect Step Input Concentration at the Feed Side of the Membrane Surface on the Diffusion Coefficient Evaluation

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2006
Jirina Cermakova
Abstract 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. [source]

Novel Poly(vinyl alcohol)-tetraethoxysilane hybrid matrix membranes as oxygen barriers,

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007
Mallikarjunagouda B. Patil
Abstract Novel type of membranes based on poly(vinyl alcohol) crosslinked with tetraethoxysilane have been prepared by solution casting and solvent-evaporation method. The membranes thus formed were characterized by Fourier transform infrared spectroscopy (FTIR) to study the chemical interactions, X-ray diffraction (XRD), and thermogravimetry (TGA) to investigate morphological and thermal properties. Membranes were prepared in two different thicknesses (30 and 55 ,m) and used for measuring the oxygen permeability under varying feed pressures (maintaining the desired pressure differential across the membrane) in the range from 1 to 50 kg/cm2 pressure. Oxygen permeability of the membranes ranged from 0.0091 to 1.6165 Barrer for 30 ,m and 0.0305 to 0.1409 Barrer for 55-,m thick membranes by increasing the feed pressures on the feed side. Except at 50 kg/cm2 pressure, the observed oxygen permeability values are almost close to total permeability. Membranes of this study could be useful as oxygen barriers for applications in food packaging industries. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 273,278, 2007 [source]

Influence of the Non-Perfect Step Input Concentration at the Feed Side of the Membrane Surface on the Diffusion Coefficient Evaluation

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2006
Jirina Cermakova
Abstract 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. [source]

Basic equations of mass transfer through biocatalytic membrane layer

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009
Endre Nagy
Abstract The diffusive and convective mass transport through biocatalytic membrane layer (membrane bioreactor), without and with biochemical reactions, have been investigated. Similarly to the two-film theory for gas-liquid system with diffusive mass transport, only, mass transfer rates have been developed for the biocatalytic membrane layer and for the concentration boundary layer on the feed side of the membrane. Overall mass transfer coefficient has also been defined involving the two-layer, simultaneous mass transfer, namely the mass transfer through the concentration boundary layer and biocatalytic membrane layer. The effect of the convective velocity (Pe number) and the biochemical reaction rate, namely first-order and zero-order reactions as limiting cases of the Monod kinetics, are demonstrated on the mass transfer coefficients accompanied by chemical reaction and on the concentration profiles. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]