scholarly journals Experimental Mixed-Gas Permeability, Sorption and Diffusion of CO2-CH4 Mixtures in 6FDA-mPDA Polyimide Membrane: Unveiling the Effect of Competitive Sorption on Permeability Selectivity

Membranes ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 10 ◽  
Author(s):  
Giuseppe Genduso ◽  
Bader Ghanem ◽  
Ingo Pinnau
Keyword(s):  
Infinite Dilution ◽  
Gas Permeability ◽  
Diffusion Theory ◽  
Linear Trend ◽  
Effective Diffusion ◽  
Gas Diffusion ◽  
Competitive Sorption ◽  
Gas Solubility ◽  
Mixed Gas ◽  
Polyimide Membrane

The nonideal behavior of polymeric membranes during separation of gas mixtures can be quantified via the solution-diffusion theory from experimental mixed-gas solubility and permeability coefficients. In this study, CO2-CH4 mixtures were sorbed at 35 °C in 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA)-m-phenylenediamine (mPDA)—a polyimide of remarkable performance. The existence of a linear trend for all data of mixed-gas CO2 versus CH4 solubility coefficients—regardless of mixture concentration—was observed for 6FDA-mPDA and other polymeric films; the slope of this trend was identified as the ratio of gas solubilities at infinite dilution. The CO2/CH4 mixed-gas solubility selectivity of 6FDA-mPDA and previously reported polymers was higher than the equimolar pure-gas value and increased with pressure from the infinite dilution value. The analysis of CO2-CH4 mixed-gas concentration-averaged effective diffusion coefficients of equimolar feeds showed that CO2 diffusivity was not affected by CH4. Our data indicate that the decrease of CO2/CH4 mixed-gas diffusion, and permeability selectivity from the pure-gas values, resulted from an increase in the methane diffusion coefficient in mixtures. This effect was the result of an alteration of the size sieving properties of 6FDA-mPDA as a consequence of CO2 presence in the 6FDA-mPDA film matrix.

scholarly journals Highly Permeable Matrimid®/PIM-EA(H2)-TB Blend Membrane for Gas Separation

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 46 ◽  
Author(s):  
Elisa Esposito ◽  
Irene Mazzei ◽  
Marcello Monteleone ◽  
Alessio Fuoco ◽  
Mariolino Carta ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Gas Transport ◽  
Gas Permeability ◽  
Time Lag ◽  
Gas Diffusion ◽  
Gas Permeation ◽  
Spectrometric Analysis ◽  
Competitive Sorption ◽  
Transport Parameters ◽  
Mixed Gas

The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H2)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H2, He, O2, N2, CO2 and CH4 were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO2/CH4 mixture and a 15/85 vol % CO2/N2 mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H2)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO2/CH4 mixture as compared to the CO2/N2 mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N2 and CH4 diffusion coefficients strongly increase in the presence of CO2, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H2)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.

Effect of annealing on gas permeability and mechanical properties of polylactic acid/talc composite films

2017 ◽  
Vol 33 (4) ◽  
pp. 361-383 ◽  
Author(s):  
Amir Ghassemi ◽  
Siavosh Moghaddamzadeh ◽  
Carl Duchesne ◽  
Denis Rodrigue
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Annealing Time ◽  
Annealing Temperature ◽  
Gas Permeability ◽  
Composite Films ◽  
Gas Diffusion ◽  
Gas Solubility ◽  
Thermal And Mechanical Properties ◽  
Film Blowing

In this study, composite films based on polylactic acid and talc were prepared by extrusion film blowing to determine the effect of annealing temperature, annealing time, and talc content on the morphology and gas permeability, as well as thermal and mechanical properties. The results showed that annealing temperature, annealing time, and talc content have a direct effect on polylactic acid crystallinity leading to changes in gas permeability and gas diffusion coefficient, while gas solubility was constant. This effect is related to the talc particles and polylactic acid crystals producing higher tortuosity in the films. Finally, a direct relation between crystallinity level, mechanical properties and gas permeability was observed for all the conditions tested.

Sorption Kinetics of High Pressure Gases in Polymeric Tubing Materials

2006 ◽  
Author(s):  
P. Jaeger ◽  
S. Buchner ◽  
R. Eggers
Keyword(s):  
Diffusion Coefficients ◽  
Gas Permeability ◽  
Gravimetric Method ◽  
Sorption Kinetics ◽  
Operating Pressure ◽  
Gas Solubility ◽  
Atmospheric Conditions ◽  
High Solubility ◽  
Industrial Practice ◽  
Kinetics Of

A gravimetric method was applied to determine the sorption kinetics of gases into polymers. Diffusivity as well as sorption capacity are determined directly. Data of gas permeability that are required for calculating leakage rates in polymeric flexile gas and oil ducts may be retrieved by multiplying the obtained diffusion coefficients and the gas solubility. In general carbon dioxide enters polymers to the highest extent. In industrial practice, the high solubility of CO2 e.g. may lead to explosive decompression of sealings once the operating pressure is reduced to atmospheric conditions. Diffusion coefficients are presented in the range of 75 to 130°C at 2 to 30 MPa.

Modelling microbial growth and biomass accumulation during methane oxidation in unsaturated soil

2020 ◽  
Vol 57 (2) ◽  
pp. 189-204
Author(s):  
Song Feng ◽  
Anthony Kwan Leung ◽  
Hong Wei Liu ◽  
Charles Wang Wai Ng ◽  
Wan Peng Tan
Keyword(s):  
Methane Oxidation ◽  
Unsaturated Soil ◽  
Reactive Transport ◽  
Microbial Growth ◽  
Gas Permeability ◽  
Biomass Accumulation ◽  
Gas Diffusion ◽  
Class B ◽  
Water Gas ◽  
Soil Pores

Microbial aerobic methane oxidation (MAMO) affects methane emissions through landfill covers by not only consuming methane, but also causing biomass accumulation associated with bacterial growth. Although the reduction of soil porosity by biomass accumulation has been well recognized, most existing models ignore this effect when estimating MAMO efficiency. The present study proposes a newly improved theoretical model that could consider the effects of both microbial growth and biomass accumulation on MAMO during coupled water–gas–heat reactive transport in unsaturated soil. Comprehensive batch incubation tests were performed to determine the input parameters required. Part of a set of published experimental data was used to validate the new model, while the remainder of the dataset was used to evaluate the model predictability of soil–microbe interaction (i.e., class B prediction). When ambient temperature is relatively high (30 °C), ignoring biomass accumulation would lead to an overestimation of MAMO efficiency by more than three times. As the biomass accumulated in soil pores, the water permeability, gas permeability, and gas diffusion in the unsaturated soil reduced, consequently limiting the supply of oxygen to the bacteria for MAMO to take place.

Ocean Engineering Concrete Using High-Volume GGBS

2012 ◽  
Vol 238 ◽  
pp. 71-74 ◽  
Author(s):  
Ke Liang Li
Keyword(s):  
Mechanical Property ◽  
Diffusion Coefficient ◽  
Effective Diffusion ◽  
Chloride Ion ◽  
High Volume ◽  
Gas Diffusion ◽  
Good Mechanical Property ◽  
Ocean Engineering ◽  
Volume Stability ◽  
Chloride Ion Penetration

To improve ocean engineering durability, concrete using high-volume ground granulated blast-furnace slag (GGBS) was prepared, its mechanical property and durability were investigated. 4% activator and 61% GGBS were used to replace 65% cement in cementitious material. Activator was used to improve workability, volume stability and early strength of high-volume GGBS concrete. Ocean concrete using high-volume GGBS has good impermeability with small gas diffusion coefficient and relative permeability coefficient. As the good property of resistance to chloride-ion penetration with a low effective diffusion coefficient, it can protect steel-bar from corrosions. Property of frost resistance is also favorable. Expansions caused by alkali-silica reaction and sulfate attack fall down markedly after using high-volume GGBS. It is proved that the high-volume GGBS concrete with good mechanical property and durability is applicable to the constructing of ocean engineering concrete.

Compress effects on porosity, gas-phase tortuosity, and gas permeability in a simulated PEM gas diffusion layer

2015 ◽  
Vol 39 (11) ◽  
pp. 1528-1536 ◽  
Author(s):  
Mayken Espinoza ◽  
Martin Andersson ◽  
Jinliang Yuan ◽  
Bengt Sundén
Keyword(s):  
Gas Phase ◽  
Diffusion Layer ◽  
Gas Permeability ◽  
Gas Diffusion Layer ◽  
Gas Diffusion

Gas Diffusion and Re-Diffusion in Polyethylene Foams

2009 ◽  
Vol 283-286 ◽  
pp. 583-588
Author(s):  
J. Escudero ◽  
J. Lázaro ◽  
E. Solórzano ◽  
Miguel A. Rodríguez-Pérez ◽  
Jose A. de Saja
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Process ◽  
Static Loading ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Gas Diffusion ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Compressive Creep ◽  
Closed Cell

In this work, the effective diffusion coefficient of the gas contained in closed cell polyethylene foams under static loading is measured. To do this, compressive creep experiments were performed on low density polyethylene foams produced under a gas diffusion process. Density dependence of this coefficient has been analysed as well as the variation of pressure with time inside the cells. Finally, immediately after compressive creep, the recovery behaviour of the foams was also characterised. Different abilities for recovering were observed depending on the density of the foam and the absolute recovery resulted independent of the initial stress applied.

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