scholarly journals Gas Transport in Mixed Matrix Membranes: Two Methods for Time Lag Determination

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 28 ◽  
Author(s):  
Alessio Fuoco ◽  
Marcello Monteleone ◽  
Elisa Esposito ◽  
Rosaria Bruno ◽  
Jesús Ferrando-Soria ◽  
...  

The most widely used method to measure the transport properties of dense polymeric membranes is the time lag method in a constant volume/pressure increase instrument. Although simple and quick, this method provides only relatively superficial, averaged data of the permeability, diffusivity, and solubility of gas or vapor species in the membrane. The present manuscript discusses a more sophisticated computational method to determine the transport properties on the basis of a fit of the entire permeation curve, including the transient period. The traditional tangent method and the fitting procedure were compared for the transport of six light gases (H2, He, O2, N2, CH4, and CO2) and ethane and ethylene in mixed matrix membranes (MMM) based on Pebax®1657 and the metal–organic framework (MOF) CuII2(S,S)-hismox·5H2O. Deviations of the experimental data from the theoretical curve could be attributed to the particular MOF structure, with cavities of different sizes. The fitting procedure revealed two different effective diffusion coefficients for the same gas in the case of methane and ethylene, due to the unusual void morphology in the MOFs. The method was furthermore applied to mixed gas permeation in an innovative constant-pressure/variable-volume setup with continuous analysis of the permeate composition by an on-line mass-spectrometric residual gas analyzer. This method can provide the diffusion coefficient of individual gas species in a mixture, during mixed gas permeation experiments. Such information was previously inaccessible, and it will greatly enhance insight into the mixed gas transport in polymeric or mixed matrix membranes.

2016 ◽  
Vol 148 ◽  
pp. 1259-1265 ◽  
Author(s):  
Norwahyu Jusoh ◽  
Yin Fong Yeong ◽  
Kok Keong Lau ◽  
Azmi Mohd Shariff

Author(s):  
V. Giel ◽  
B. Galajdová ◽  
D. Popelková ◽  
J. Kredatusová ◽  
M. Trchová ◽  
...  

2011 ◽  
Vol 77 (1) ◽  
pp. 128-136 ◽  
Author(s):  
F. Moghadam ◽  
M.R. Omidkhah ◽  
E. Vasheghani-Farahani ◽  
M.Z. Pedram ◽  
F. Dorosti

SPE Polymers ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 125-138
Author(s):  
Saeid Maghami ◽  
Morteza Sadeghi ◽  
Arjomand Mehrabani‐Zeinabad ◽  
Mehdi Simiari

Membranes ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 19 ◽  
Author(s):  
Gianni Golemme ◽  
Anna Santaniello

Despite the outstanding chemical, thermal and transport properties of amorphous and glassy perfluorinated polymers, only few works exist on the preparation and transport properties of perfluoropolymer/molecular sieves mixed-matrix membranes (MMMs), probably because of their poor compatibility. In this review, the compatibilization of ceramic molecular sieves with perfluorinated matrices is considered first, examining the effect of the surface treatment on the gas transport properties of the filler. Then the preparation of the defect-free hybrid membranes and their gas separation capabilities are described. Finally, recent modelling of the gas transport properties of the perfluoropolymer MMMs is reviewed. The systematic use of molecular sieves of different size and shape, either permeable or impermeable, and the calculation of the bulk transport properties of the molecular sieves—i.e., the unrestricted diffusion and permeability—allow to understand the nature of the physical phenomena at work in the MMMs, that is the larger the perfluoropolymer fractional free volume at the interface, and restricted diffusion at the molecular sieves. This knowledge led to the formulation of a new four-phase approach for the modelling of gas transport. The four-phase approach was implemented in the frame of the Maxwell model and also for the finite element simulation. The four-phase approach is a convenient representation of the transport in MMMs when more than one single interfacial effect is present.


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