• Membrane and Water Treatment
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• v.5 no.4
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• pp.265-279
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• 2014

Pervaporation is the most promising technique for the recovery of ethanol from the fermentation system. To date, extensive research has been conducted on the exploration of membrane materials with favorable properties. In this paper, we primarily review the performance of adsorbent-filled rubbery membranes. In addition, the fundamental mechanisms of ethanol and water molecules transportation through composite membranes are demonstrated, particularly from the perspective of cluster formation. Finally, future prospects are also analyzed to develop the guidelines for the future development of excellent membrane materials for ethanol concentration. This paper is not meant to be an exhaustive overview, rather a specialized summary that allows readers to select the information appropriated to their topics.

• Structural Engineering and Mechanics
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• v.13 no.4
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• pp.437-453
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• 2002

In this paper, dynamic stiffness and flexibility for circular membranes are analytically derived using an efficient mixed-part dual boundary element method (BEM). We employ three approaches, the complex-valued BEM, the real-part and imaginary-part BEM, to determine the dynamic stiffness and flexibility. In the analytical formulation, the continuous system for a circular membrane is transformed into a discrete system with a circulant matrix. Based on the properties of the circulant, the analytical solutions for the dynamic stiffness and flexibility are derived. In deriving the stiffness and flexibility, the spurious resonance is cancelled out. Numerical aspects are discussed and emphasized. The problem of numerical instability due to division by zero is avoided by choosing additional constraints from the information of real and imaginary parts in the dual formulation. For the overdetermined system, the least squares method is considered to determine the dynamic stiffness and flexibility. A general purpose program has been developed to test several examples including circular and square cases.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.131-139
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• 2020

The current study focused on the preparation of low-cost PVC-based adsorbing membrane. Metakaolin, as available adsorbent, was embedded into the PVC matrix via solution blending method. The as-prepared PVC/metakaolin mixed matrix membranes were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), pure water permeability and contact angle measurements. The results confirmed the improvement of PWP and hydrophilicity due to the presence of metakaolin in the PVC matrix. Additionally the structure of PVC membrane was changed due to the incorporation of metakaolin in the polymer matrix. The static adsorption capacity of all samples was determined through dye removal. The effect of metakaolin dosage (0-7%) and pH (4, 8, 12) on dye adsorption capacity was investigated. The results depicted that the highest adsorption capacity was achieved at pH of 4 for all samples. Additionally, adsorption data were fitted on Langmuir, Freundlich, and Temkin models to determine the appropriate governing isotherm model. Finally, the dynamic adsorption capacity of the optimum PVC/metakaolin membrane was studied using dead-end filtration cell. The dye removal efficiency was determined for pure PVC and PVC/metakaolin membrane. The results demonstrated that PVC/metakaolin mixed matrix membrane had a high adsorption capacity for dye removal from aqueous solution.

• Membrane Journal
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• v.30 no.4
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• pp.260-268
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• 2020

Mixed-matrix carbon molecular sieve membranes containing conventional and hierarchically structured 5A were synthesized for application in oxygen (O₂)/nitrogen (N₂) separation. In general, incorporating 5A fillers into porous carbon matrices dramatically increased the permeability of the membrane with a marginal decrease in selectivity, resulting in very attractive O₂/N₂ separation performances. Hierarchical zeolite 5A, which contains both microporous and mesoporous domains, improved the separation performance further, indicating that the mesopores in the zeolite can serve as an additional path for rapid gas diffusion without sacrificing O₂/N₂ selectivity substantially. This facile strategy successfully and cost-effectively pushed the performance close to the Robeson upper bound. It produced high performance membranes based on Matrimid^® 5218 polyimide and zeolite 5A, which are inexpensive commercial products.

• Membrane and Water Treatment
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• v.7 no.6
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• pp.507-520
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• 2016

The effect of ZnO on cellulose acetate in the removal of benzophenone-3 (BP-3) was investigated. The benzophenone-3 (BP-3) which is an endocrine disrupting chemical (EDC) was completely removed (100%) from the drinking water using Cellulose Acetate (CA) and zinc oxide (ZnO) composite membranes. The membranes were prepared by DIPS method and the filtration experiments were conducted by dead end filtration unit. The macrostructure of the membrane were studied by ATR-IR and XRD Spectra's. Atomic force microscopy (AFM) and Scanning electron microscopy (SEM) were used to study the micro properties of the membranes. The laboratory experiments such as water uptake study and pure water flux performed to confirm the increasing hydrophilicity. The enhancing hydrophilicity was confirmed with respect to higher the concentration of nanoparticles. Evaluation of BP-3 removal was carried in different experimental conditions, such as, different Trans membrane pressure and different concentration of feed. The membrane with low pressure showed better performance by rejecting 100% of BP-3. However, 1 ppm, 3 ppm and 6 ppm of feed solution was used and among them 3 ppm of feed solution gives 100% rejection. The ZnO nanoparticales enhances the performance of CA membrane by showing maximum rejection.

• Membrane Journal
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• v.25 no.3
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• pp.295-300
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• 2015

PDMS-NaA zeolite membranes were prepared by adding 0~40 wt% NaA zeolite. Based on SEM observation, NaA zeolite was dispersed in the PDMS-NaA zeolite membranes with $2{\sim}5{\mu}m$. The permeabilities of $H_2$ and $N_2$ gases through PDMS-NaA zeolite membranes increased as NaA zeolite contents increased and $H_2$ gas had better permeabilities than $N_2$. The selectivity ($H_2/N_2$) of PDMS-NaA zeolite membranes increased as NaA zeolite contents increased.

• Membrane Journal
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• v.28 no.1
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• pp.55-61
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• 2018

With vigorous development of petroleum and chemical industry, emission of carbon dioxide has attracted tremendous attention globally due to global warming problem and abnormal climate change. To address these problems, in this study, a PEGBEM-g-POEM graft copolymer with high $CO_2$ affinity was synthesized and $CaCO_3$ was incorporated to form mixed matrix membranes (MMMs) for enhancement of $CO_2$ permeance. By varying the addition weight of $CaCO_3$ in MMMs, high separation performance of $CO_2$ over $N_2$ was obtained. At 50 wt% loading of $CaCO_3$, the greatest separation performance was obtained with an enhanced $CO_2$ permeance from 22.5 to 28.16 GPU and slightly increased $CO_2/N_2$ selectivity from 44.7 to 45.42. It resulted from the increased $CO_2$ solubility of MMMs due to specific interaction between $CaCO_3$ and $CO_2$ molecules. Upon excess loading of $CaCO_3$, MMMs exhibited loss of $CO_2$ separation performance due to the formation of interfacial defects. Based on this result, it is considered that the proper addition of $CaCO_3$ is crucial for improvement of $CO_2$ separation performance.

• Membrane Journal
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• v.32 no.5
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• pp.325-335
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• 2022

In this study, zeolitic imidazolate framework-9 (ZIF-9) was synthesized and Pebax/ZIF-9 mixed membranes were prepared by varying the content in poly(ether-b-amide)-1657 (Pebax-1657), and then a single gas (N₂, CO₂) was permeated to investigate the gas permeation characteristics of the mixed membrane. As the ZIF-9 content incorporated into the pure Pebax membrane increased, the N₂ permeability gradually decreased, and the CO₂ permeability increased up to the Pebax/ZIF-9 3 wt% mixed membrane, and then decreased at the content thereafter. And among the mixed membranes, the Pebax/ZIF-9 3 wt% mixed membrane showed the highest selectivity of 69.3 by selectively accepting CO₂ as the gate-opening phenomenon occurred for the polar gas, CO₂. In addition, both the CO₂ permeability and the CO₂/N₂ selectivity increased, resulting in the closest Robeson upper-bound.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.393-402
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• 2021

In this study, a mixed matrix membrane was prepared by putting the zeolitic imidazolate framework-7 (ZIF-7) synthesized in Pebax-1657 and Pebax-2533, which are representative poly(ether-b-amide), and the permeability properties of single gas such as N₂ and CO₂ were investigated. From the gas permeation results, in the case of N₂, both the Pebax-1657/ZIF-7 and Pebax-2533/ZIF-7 mixed matrix membranes showed a similar phenomenon in which the permeability decreased with the incorporation of ZIF-7. For CO₂ permeability, the tendency was slightly different depending on the type of polymer. In the Pebax-1657/ZIF-7 mixed membrane, the CO₂ permeability decreased in the range of 0~3 wt% of ZIF-7, and increased at higher contents. The CO₂ permeability of the Pebax-2533/ZIF-7 mixed matrix membrane gradually decreased without increasing the permeability in the range of 0~5 wt% of ZIF-7. Regarding CO₂/N₂ selectivity, both mixed films showed a tendency to increase with increasing the ZIF-7 content. In particular, Pebax-2533/ZIF-7 5 wt% showed the best gas permeation performance compared to other mixed matrix membrane. This is thought to be because ZIF-7 shows better compatibility with Pebax-2533 than that of Pebax-1657 and also better CO₂ selective property.

• Membrane Journal
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• v.33 no.5
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• pp.240-247
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• 2023

Even among gas separation methods, CO₂ capture and separation via membranes is an ever-growing field, with many different membrane compositions continually being developed. Ionic liquid (IL) based composite membranes show excellent performance values in separating CO₂. Similarly, various copolymer/IL composite membranes also display improved performance. The addition of fillers such as graphene oxide to these copolymer/IL composite membranes shows a further enhanced version of these fillers, most likely due to the strong interactions that occur between ILs and organic fillers, which consequently improves factors such as the affinity, selectivity, and adsorption of CO₂. Copolymer/IL composite membranes utilizing a metal-organic framework (MOF) showed improved CO₂ permeability. This review discusses the study of various combinations of ionic liquid and copolymer composite membranes for carbon dioxide separation.