A shortcut method for faster determination of permeability coefficient from time lag experiments

Al-Ismaily, M.; Wijmans, J.G.; Kruczek, Boguslaw

doi:10.1016/j.memsci.2012.08.009

Cited by 32 publications

(15 citation statements)

References 19 publications

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“…Since the magnitude of this pressure decay must be orders of magnitude smaller than the feed pressure, commercially available absolute pressure transducers do not have a sufficient resolution to carry out this measurement. To solve this problem, the upstream part of a constant volume system used for membrane characterization in the conventional timelag method was modified, as described previously by Al-Ismaily et al [13]. Figure 2 shows a schematic diagram of the experimental setup.…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

“…To solve this problem, the actual gas permeation experiment is started by first opening the valve in the working volume, while the valve between the working and reference volumes is opened, followed by immediate closing of the latter valve. Although this approach precludes recording the pressure decay in the first couple of seconds of the experiment, it allows to accurately monitoring the pressure decay afterwards [13]. Also, during the entire gas permeation experiment, the downstream section is continuously evacuated to ensure that the boundary condition, C(L,t) = 0, is satisfied.…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

“…In addition, the measurements of the time lag involves the contributions of many other system-related response times; therefore, in the case of highly diffusive and thin membranes, in which the time lag is small, the influence of system-related delays cannot be neglected [10,11,12]. On the other hand, in the case of barrier materials characterized by very low diffusion coefficients, the actual time to reach quasisteady state might very long, which precludes application of the conventional time-lag method [13].…”

Section: Introductionmentioning

confidence: 99%

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Membrane Characterization Based on the Upstream Pressure Decay in a Dynamic Gas Permeation Test

Al-Qasas¹,

Thibault

Kruczek

2014

JFFHMT

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The time-lag method is believed to be the most usable method for extracting the membrane properties via a simple dynamic permeation experiment; however this method suffers from major drawbacks that limit its use for some materials and under certain conditions. One of the major drawbacks of the time-lag method is that it relies on monitoring the pressure rise downstream from the membrane due to gas permeation, whereas the method is derived by assuming that the pressure downstream from the membrane is maintained at zero during the entire permeation experiment. To rectify this problem, it is proposed to characterize the membrane based on the pressure decay upstream from the membrane during a conventional time-lag experiment, while continuously evacuating the downstream side of the membrane. This modification allows for a better adherence to the boundary conditions on which the time-lag method relies. Right after initiation of the gas permeation experiment, the membrane behaves as a semi-infinite solid, and the rate of pressure decay is directly proportional to the square root of time. Once the permeating gases emerge downstream from the membrane, the membrane no longer behaves as a semi-infinite solid and the pressure decay becomes a non-linear function of the square root of time. In the proposed new method, the membrane properties are extracted based on the deviation of the recorded pressure decay from the semi-infinite behavior in the square root of the time domain. In this paper, we present the mathematical bases of the new method along with preliminary experimental results. Results indicate that diffusivity, solubility and permeability of nitrogen in polyphenylene oxide (PPO) membrane used in this study are very close to the literature values.

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Section: Experimental Procedures and Resultsmentioning

confidence: 99%

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Membrane Characterization Based on the Upstream Pressure Decay in a Dynamic Gas Permeation Test

Al-Qasas¹,

Thibault

Kruczek

2014

JFFHMT

Self Cite

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“…The prefactor f ( ϵ 0 ) solely depends on porosity ϵ 0 and can be calculated numerically. Typical values for the diffusion coefficient for polymer/carbon dioxide systems are in the range D feed = 10 −12 –10 −10 m 2 s −1 . Therefore the parameters D feed = 10 −11 m 2 s −1 and R = 1 µm are used.…”

Section: Creep and Diffusion In Polymersmentioning

confidence: 99%

Analysis of compaction and life‐time prediction of porous polymer membranes: influence of morphology, diffusion and creep behaviour

Handge

2016

Polymer International

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In membrane applications, large values of permeability and selectivity are generally desired during the whole period of application. The permeability of porous polymer membranes often is reduced by the effect of compaction. Compaction of polymer membranes is a time‐dependent process which is strongly determined by the viscoelastic properties of the polymer and its plasticisation caused by the feed medium (e.g. a liquid medium or a process gas in the case of porous support structures). In this study, the time‐dependent compaction of porous polymer membranes under pressure is modelled. The influence of viscoelastic and diffusion properties of the polymer material on the permeability of the membrane is analysed for different types of membrane morphologies. The life‐time of a porous polymer membrane is associated with the time at which the glass transition is achieved in a creep experiment. Equations are derived in order to estimate the maximum life‐time of polymer membranes based on compaction. The analysis reveals that the diffusion coefficient, the average retardation time in creep, the magnitude of creep compliance and the time–temperature–pressure shift factor strongly influence compaction of microporous membranes. Generally, a larger tortuosity at constant porosity yields a lower life‐time of the membrane. Buckling of cell struts is the dominant failure mechanism in porous membranes with a very high porosity and allows an estimation of life‐time. © 2016 Society of Chemical Industry

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“…Permeation through polymers has been investigated analytically by modified time‐lag analyses and with various diffusion models, within finite volume systems and at various experimental conditions . Application of time‐lag analysis has been applied to extract diffusion information along with permeation data and both dual sorption and free volume theories have been proposed to understand the transport mechanism within polymer membranes.…”

Section: Introductionmentioning

confidence: 99%

The effect of mass transfer resistance and nonuniform initial solvent concentration on permeation through polymer membranes

Zielinski

Altınkaya

2017

J of Applied Polymer Sci

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A numerical simulation model has been developed which enables one to examine the effects of surface mass transfer resistance on the evaluation of permeation (P*), diffusion (D), and solubility (S) coefficients from unsteady-state mass transfer experiments as well as the transmission rate. A complementary analytical expression has been developed which validates the numerical model and facilitates the evaluation of the concentration dependence of P*, D, and S from sequential step-change experiments, under experimental conditions when the surface mass transfer resistance can be neglected.

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A shortcut method for faster determination of permeability coefficient from time lag experiments

Cited by 32 publications

References 19 publications

Membrane Characterization Based on the Upstream Pressure Decay in a Dynamic Gas Permeation Test

Membrane Characterization Based on the Upstream Pressure Decay in a Dynamic Gas Permeation Test

Analysis of compaction and life‐time prediction of porous polymer membranes: influence of morphology, diffusion and creep behaviour

The effect of mass transfer resistance and nonuniform initial solvent concentration on permeation through polymer membranes

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