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This article presents various gas separation membrane simulation techniques based on typical engineering and design techniques for membrane process description. Modelling and design processes are tasks that use different tools to simulate the profile of the process. Given some initial data, such as flow, temperature, concentration and pressure, the correlations presented can be used to perform simulations. After selecting the flow configuration, types of membrane element and settings, it can be determined whether the process is working as expected. The design process, on the other hand, involves the specific results to be obtained, namely the material and geometry estimation of the membrane itself. This paper presents the challenges faced in the membrane simulation study for gas separation, which is important to predict and design the industry scale of gas separation process. At the same time, attainment of accurate results at non-ideal conditions remains challenging. More experimental data and research are needed to support and validate the results.

In this work, we report the effect of seed particle size towards the formation of NaX zeolite membranes through single and multi-stage hydrothermal growth methods. A seed layer was firstly deposited onto the α-alumina support via vacuum-assisted seeding technique prior to hydrothermal growth of the membrane layer. The morphology and crystallinity of the membranes were characterized by using scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. From the results obtained, by using smaller seed particles of 750 nm, the growth of the membrane layer was enhanced due to minimum gaps found in between the seed particles. The N2 gas permeation results showed that the multistage synthesis method has successfully reduced the defects of the membranes. However, it was observed that the presence of zeolite NaP impurities in the membrane layer became more significant along with the increase of the synthesis stage.

Zeolites embark as a promising inorganic filler for hybrid membrane fabrication. However, small size of microporous structure and long diffusion path length of zeolites may restrict gas transport across the pore channel. Thus, hierarchical zeolites have been introduced as a prominent approach to overcome the diffusion limitation via the presence of bimodal porous structures of micropore and mesopore. In the present work, pristine PEBAX 1657 and hierarchical Linde Type-T (h-LTT) zeolite particles were prepared for the fabrication of hybrid membrane in CO2/CH4 separation. The resultant particles and membrane were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and thermogravimetric analysis (TGA). FESEM analysis demonstrates the dense symmetric structure of pristine PEBAX 1657 membrane and column-shape morphology of h-LTT zeolite particles with average particle size of 1.38 µm. On the other hand, pristine PEBAX 1657 membrane also exhibit a semi-crystalline structure and a thermal stability up to 370 °C. In addition, the permeation properties of the pristine membrane for single gas was also tested. The pristine membrane demonstrates CO2 permeability and CO2/CH4 selectivity of 74.27 Barrer and 14.26, respectively.

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Composite membranes comprising NH2-MIL-125(Ti)/PEBAX coated on PDMS/PSf were prepared in this work, and their gas separation performance for high CO2 feed gas was investigated under various operating circumstances, such as pressure and CO2 concentration, in mixed gas conditions. The functional groups and morphology of the prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). CO2 concentration and feed gas pressure were demonstrated to have a considerable impact on the CO2 and CH4 permeance, as well as the CO2/CH4 mixed gas selectivity of the resultant membrane. As CO2 concentration was raised from 14.5 vol % to 70 vol %, a trade-off between permeance and selectivity was found, as CO2 permeance increased by 136% and CO2/CH4 selectivity reduced by 42.17%. The membrane produced in this work exhibited pressure durability up to 9 bar and adequate gas separation performance at feed gas conditions consisting of high CO2 content.

The development of Faujasite (FAU) zeolite membranes has been a subject of interest for various application due to the uniform pore’s characteristic, excellent thermal, and chemical stability as well as catalytic and ion-exchange properties of FAU zeolite membranes. However, the synthesis of FAU zeolite membranes with minimum defects is still challenging as there are multiple variables in the synthesis process which need to be controlled. This review started with an overview on zeolites, zeolite membranes, and their applications. Then, various methods used for the preparation of FAU zeolite membrane are discussed. Subsequently, the variation of synthesis techniques and parameters for obtaining high quality of FAU zeolite membrane are reviewed. Then, the parameters affecting the formation of FAU zeolite membrane are highlighted.

This work reported on the fabrication of mixed matrix membranes by incorporating NH2-MIL-125 (Ti) nanofiller into 6FDA–durene polymer matrix for CO2/CH4 separation. The structural properties and morphology of the nanofillers and resultant membranes were investigated by X-ray diffraction, Brunauer Emmett and Teller, field emission scanning electron microscope, energy-dispersive X-ray spectroscopy mapping, thermogravimetric analysis and free fractional volume. The results showed that the CO2 and CH4 single gas permeability, as well as CO2/CH4 ideal selectivity were improved by incorporating NH2-MIL-125 (Ti) into the polymer matrix. Membrane loaded with 7.0 wt% of NH2-MIL-125 (Ti) filler showed the highest CO2 permeability of 1115.70 Barrer and CO2/CH4 selectivity of 37.10, surpassing the 2008 Robeson upper bound. Furthermore, improvement of CO2 permeability of 119% and increment of 331% for gas pair selectivity in comparison with pure membrane were achieved. The results obtained in this work is due to the high porosity of nanofillers besides the attraction of amine functional group towards CO2. Overall, incorporation of amine-functionalized MIL-125 (Ti) nanofillers into 6FDA–durene polymer matrix has enhanced the separation performance of the membrane in CO2/CH4 separation.

The challenges in developing high CO2 gas fields are governed by several factors such as reservoir condition, feed gas composition, operational pressure and temperature, and selection of appropriate technologies for bulk CO2 separation. Thus, in this work, we report an optimization study on the separation of CO2 from CH4 at high CO2 feed concentration over a functionalized mixed matrix membrane using a statistical tool, response surface methodology (RSM) statistical coupled with central composite design (CCD). The functionalized mixed matrix membrane containing NH2-MIL-125 (Ti) and 6FDA-durene, fabricated in our previous study, was used to perform the separation performance under three operational parameters, namely, feed pressure, temperature, and CO2 feed concentration, ranging from 3.5–12.5 bar, 30.0–50.0 °C and 15–70 mol%, respectively. The CO2 permeability and CO2/CH4 separation factor obtained from the experimental work were varied from 293.2–794.4 Barrer and 5.3–13.0, respectively. In addition, the optimum operational parameters were found at a feed pressure of 12.5 bar, a temperature of 34.7 °C, and a CO2 feed concentration of 70 mol%, which yielded the highest CO2 permeability of 609.3 Barrer and a CO2/CH4 separation factor of 11.6. The average errors between the experimental data and data predicted by the model for CO2 permeability and CO2/CH4 separation factor were 5.1% and 3.3%, respectively, confirming the validity of the proposed model. Overall, the findings of this work provide insights into the future utilization of NH2-MIL-125 (Ti)/6FDA-based mixed matrix membranes in real natural gas purification applications.

In this work, we systematically study the performance of tubular ZIF-8 membranes in the separation of small molecules including H

Presently, composite membranes emerged as a promising approach to overcome the limitations of polymeric and inorganic membranes particularly in acid gas separation. In the present work, composites membranes were fabricated by combining hierarchical T-Type (h-zeolite T) zeolite and PEBA-1657 at different filler composition that ranging from 5 wt% - 30 wt% for the CO

The attractive features of this work lies on the optimization of spinning parameters including, take-up speed and air-gap distance on the fabrication of NH2-MIL-53(Al)/CA Hollow fiber mixed matrix membranes (HFMMMs) for gases separation. The morphology and distribution of particles in the resultant HFMMMs were characterized by using FESEM and EDX mapping, respectively. FESEM images showed that the increase in take-up speed and air-gap distance reduced the outer diameters of HFMMMs from 275.5 µm to 110.1 µm and 719.1 µm to 648.4 µm, respectively. The gas permeation results exhibited that the permeance values were reduced and ideal selectivities were improved with the increment of take-up speed. Increasing trend of ideal selectivities could be because of progression of polymer orientation, packing and mono-disperse space which suppressed the non-selective voids and Knudsen pores in the HFMMMs. However, variation of air-gap distance produced “V” and “A” pattern for permeance and ideal selectivity values, respectively, for all HFMMMs spun at different take-up speeds. The HFMMM spun at optimum spinning condition at take up speed of 12.2 m/min and air gap distances of 5.0 cm showed the highest CO2/CH4 ideal selectivity of 16.0 and CO2/N2 ideal selectivity of 12.0. Hence, optimization of spinning parameters can be considered as feasible and efficient method in order to fabricate HFMMMs with higher separation performance. The enhanced CO2 permeance and ideal selectivities demonstrated that NH2-MIL-53(Al)/CA HFMMM spun at optimum condition is potential for industrial gas separation.

In the current work, thermal treatment, PDMS coating, and combined thermal treatment with PDMS coating methods were applied over NH2-MIL-53(Al)/cellulose acetate (CA) hollow fiber mixed matrix membranes (HFMMM) for CO2/CH4 and CO2/N2 separation. The results showed that upon thermal treatment at 170 °C, CO2/CH4 and CO2/N2 gas pair selectivities of HFMMM were improved from 9.1 to 9.9 and 7.7 to 8.4, respectively. On the other hand, CO2/CH4 and CO2/N2 gas pair selectivities of HFMMMs were improved from 9.1 to 14.1 and 7.7 to 12.0, respectively, after thermal treatment at 220 °C. Substantial increment in gas pair selectivities of the thermally treated fibers was mainly due to polymer densification, which condensed the voids between polymer and particles. Subsequently, PDMS-coated HFMMMs exhibited gas pair selectivities of 17.0 and 16.2, respectively, which were higher compared to the untreated and thermally treated HFMMM. Highest improvement of CO2/CH4 and CO2/N2 gas pair selectivities were found for combined...

In this work, a new type of mixed matrix membranes comprising of amino-functionalized CAU-1 as filler and cellulose acetate as polymer phase were fabricated for CO2 separation from N2. The crystallinity and morphology of the resultant fillers were verified by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The energy-dispersive X-ray (EDX) results showed that, sedimentation and agglomeration of fillers were found at loading of more than 5 wt%. Subsequently, the gases permeation results revealed that, an increase in CO2 permeability and CO2/N2 selectivity of 149% and 81%, respectively, were achieved for the membrane loaded with 5 wt% of CAU-1-NH2, as compared to pure cellulose acetate membrane.

In the current work, effect of spinning conditions including, take-up speed and air-gap distance and post-treatment methods on the fabrication of cellulose acetate hollow fiber membranes (CA-HFMs) for CO2/N2 and CO2/CH4 separations have been reported. The gas permeation results obtained in this work revealed that permeances of gases were decreased with increase in take-up speed from free fall to 12.2 m/min. Meanwhile, gas pair selectivities increased with increasing take-up speed. Subsequently, increment in air-gap distance produced the “V” pattern for gases permeances and “A” pattern of gas pair selectivities for all CA-HFMs spun at different take-up speeds. Therefore, optimum take-up speed and air gap distance of CA-HFMs of 12.2 m/min and 5.0 cm were obtained, respectively. CA-HFM spun at optimum spinning conditions showed the highest CO2/CH4 and CO2/N2 ideal selectivities of 7.9 and 6.0, respectively. On the other hand, permeation results also demonstrated that the CO2/CH4 and CO2/N2 ideal selectivities of PDMS coated CA-HFMs were higher about 70.9% and 84.1%, respectively, compared to those values obtained from thermally treated CA-HFMs. Therefore, PDMS coating is considered as an effective approach to seal the macro-voids of HFMs compared to the thermal treatment in order to achieve higher permeation performance for CO2 separations. In addition, permeation results also manifested that the CA-HFM fabricated at optimum conditions has incredible worth from the prospective of industrial separations of CO2 from flue and natural gas.

In this study, the effect of solution alkalinity towards zeolite crystallization and growth were investigated for NaX zeolite crystals and NaX zeolite membrane grown via secondary growth. NaX zeolite crystals were synthesized by using different Na2O/Al2O3 ratios of 15, 16, 17, 18 and 19. XRD and FESEM results indicated that Na2O/Al2O3 ratio of 17 and above produced NaX zeolite crystal with high crystallinity ad single phase NaX zeolite. NaX zeolite membrane were also synthesized by varying Na2O/Al2O3 ratios of 17 and 19 in order to study the growth of NaX zeolite membrane via secondary growth. Na2O/Al2O3 ratio of 17 resulted in better intercrystalline growth of the membrane layer compared with the membrane synthesized using mixture solution with Na2O/Al2O3 ratio of 19.

Exploring the efficient synthesis method is essential in producing zeolite membranes with minimum defects. Seeding prior hydrothermal synthesis (HT) is the major parameters that affecting the quality of zeolite membrane formed. The colloidal stability of the NaY seed solution and its attachment to the support were studied by varying the pH of the seed solutions. Three seeding methods, including dip-coating, spin coating and vacuum coating, were studied in forming NaY zeolite seed layer. Then, the seeded alumina supports were subjected to hydrothermal treatment (HT) in order to form NaY zeolite membranes. The effect of NaY seeds solution colloidal stability, electrostatic attachment between seeds and support and the seeding methods on the properties of the quality of the formed NaY zeolite membranes were investigated. The zeta potential of the seed solution was measured with respect to different pH of the seed solution. The formed NaY zeolite membrane samples were characterized with X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) and Energy dispersive X-Ray spectroscopy (EDX). Spin coating and vacuum coating displayed better seeds coverage onto the alumina support due to the vacuum lock mechanism however excessive seeds accumulation onto the alumina support will inhibit zeolite growth and expansion hence to produce NaY zeolite membranes with cracks. Nonetheless, seeded supports by dip coating method display less coverage on the support however with a proper selection pH of the seeding solution with relates to its zeta potential, stable aqueous colloidal dispersion of the seeds solution and better attachment between the zeolite seeds and the support could be achieved in order to form zeolite NaY membranes with least defects.

Sonochemistry is the implementation of ultrasound wave to chemical reactions and processes. Remarkable progress has been achieved over the years on ultrasonic-assisted hydrothermal synthesis in zeolites. Ultrasonic irradiation is gaining popularity among researchers due to its ability in enhancing the zeolite crystallization and shortening significantly zeolite synthesis duration. In this project, zeolite RHO were synthesized via ultrasonic irradiation and followed by hydrothermal synthesis. The effect of ultrasonic irradiation on the synthesis of zeolite RHO was investigated. The zeolite RHO samples were characterized with X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) coupled with Energy Dispersive X-ray (EDX). The application of ultrasonic irradiation treatment in current study has significantly shortened the synthesis duration of zeolite RHO from 7 days to 2 days compared to the conventional hydrothermal synthesis without ultrasonic irradiation treatment.

In this work, composite membranes were fabricated by incorporating amine-functionalized zeolitic imidazolate framework 8 (ZIF-8) into 6FDA-durene polyimide. ZIF-8 particles was functionalized by N-[3-(Dimethoxymethylsilyl)propyl] ethylenediamine (AAPTMS) and N1-(3-Trimethoxysilylpropyl) diethylenetriamine (AEPTMS). Functionalization of ZIF-8 by amine-functional group may possibly enhance the CO2/CH4 separation performances by improving the compatibility between ZIF-8 and 6FDA-durene polymer. The resultant membranes were analysed by using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersion X-ray (EDX). Then, the separation performance test were performed using pure carbon dioxide (CO2) and methane (CH4) gases. The results showed that CO2 permeability of 548 Barrer and CO2/CH4 ideal selectivity of 17 were obtained using 1.0 wt% AAPTMS-ZIF-8/6FDA-durene composite membrane, while 1.0 wt% AEPTMS-ZIF-8/6FDA-durene composite membrane exhibited CO2 permeability of 533 barrer and CO2/CH4 gas pair selectivity of 12. On the other hand, 1.0 wt% ZIF-8/6FDA-durene composite membrane showed CO2 permeability and CO2/CH4 selectivity of 610 barrer and 15, respectively. Therefore, it can be concluded in this work that, selection of another suitable amine functionalization group for the modification of ZIF-8 is needed in later works to further improve the performance of the membrane in CO2 removal from CH4.

In the last years, development of membrane technology has been gaining interest in the industry due to its simplicity, economical, and environmental benefits. Membrane separation technology has been studied for various industrial applications including air purification and natural gas sweetening. In these processes, membrane technology has proven potential to replace the existing conventional technologies such as absorption, adsorption, and cryogenic distillation. This book chapter describes the development of mixed matrix membranes incorporated with nanofillers and the utilization of them for the gas separation process. It will discuss the factors that affect the membrane separation performance including the selection of polymers and fillers for mixed matrix membranes, the membrane configurations, and the membrane fabrication methods. In addition, the discussion on the effects of different types of nanofillers on the gas separation performance of the mixed matrix membranes will also be provided.

One of the most critical issues encountered by polymeric membranes for the gas separation process is the trade-off effect between gas permeability and selectivity. The aim of this work is to develop a simple yet effective coating technique to modify the surface properties of commonly used polysulfone (PSF) hollow fiber membranes to address the trade-off effect for CO2/CH4 and O2/N2 separation. In this study, multilayer coated PSF hollow fibers were fabricated by incorporating a graphene oxide (GO) nanosheet into the selective coating layer made of polyether block amide (Pebax). In order to prevent the penetration of Pebax coating solution into the membrane substrate, a gutter layer of polydimethylsiloxane (PDMS) was formed between the substrate and Pebax layer. The impacts of GO loadings (0.0&ndash, 1.0 wt%) on the Pebax layer properties and the membrane performances were then investigated. XPS data clearly showed the existence of GO in the membrane selective layer, and the higher the amount of GO incorporated the greater the sp2 hybridization state of carbon detected. In terms of coating layer morphology, increasing the GO amount only affected the membrane surface roughness without altering the entire coating layer thickness. Our findings indicated that the addition of 0.8 wt% GO into the Pebax coating layer could produce the best performing multilayer coated membrane, showing 56.1% and 20.9% enhancements in the CO2/CH4 and O2/N2 gas pair selectivities, respectively, in comparison to the membrane without GO incorporation. The improvement is due to the increased tortuous path in the selective layer, which created a higher resistance to the larger gas molecules (CH4 and N2) compared to the smaller gas molecules (CO2 and O2). The best performing membrane also demonstrated a lower degree of plasticization and a very stable performance over the entire 50-h operation, recording CO2/CH4 and O2/N2 gas pair selectivities of 52.57 (CO2 permeance: 28.08 GPU) and 8.05 (O2 permeance: 5.32 GPU), respectively.

The Ba form of a silicoaluminophosphate-34 (SAPO-34) zeolite membrane was synthesized and investigated for carbon dioxide (CO2)/nitrogen (N2) separation with low CO2 concentration (as low as 5%) in the feed. The effects of the separation temperature, CO2 concentration in the feed, and pressure difference on the separation performance of the Ba form of a SAPO-34 zeolite membrane were investigated. A CO2 gas permeance of 17.5 × 10–7 mol/m2·s·Pa and a CO2/N2 separation selectivity of 78 were attained for the Ba form of a SAPO-34 zeolite membrane at 100 kPa pressure difference, 303 K, and 5% CO2 concentration in the feed. With low CO2 concentration (5%) in the CO2/N2 mixture, the Ba form of a SAPO-34 zeolite membrane was efficient in CO2/N2 separation and displayed good stability for the separation performance of CO2/N2 gas mixtures, in a gas separation durability test up to a total durability test time of 58 h.

Oxygen (O2) enriched air combustion via adaption of polymeric membranes has been proposed to be a feasible alternative to increase combustion proficiency while minimizing the emission of greenhouse gases into the atmosphere. Nonetheless, majority of techno-economic assessment on the O2 enriched combustion evolving membrane separation process are confined to assumption of constant membrane permeance. In reality, it is well known that membrane permeance is highly dependent upon the temperature and pressure to which it is operated. Therefore, in this work, an empirical model, which includes the effect of temperature and pressure to permeance, has been evaluated based on own experimental work using polysulfone membrane. The empirical model has been further validated with published experimental results. It is found that the model is able to provide an excellent characterization of the membrane permeance across a wide range of operating conditions for both pure and binary gas with determination coefficient of minimally 0.99.

In the current study, new types of MMMs are fabricated by incorporating NH2-MIL-53(Al) filler into cellulose acetate (CA) polymer. Subsequently, crystallinity, morphology, thermal stability, functional groups and density measurement of the resultant MMMs were verified by using different analytical tools. The results showed that the presence of NH2-MIL-53(Al) in CA matrix had enhanced the CO2 permeability, CO2/N2 and CO2/CH4 ideal selectivities from 15.5 Barrer to 52.6 Barrer, 8.8 to 23.4 and 10.7 to 28.7, respectively. The present study revealed that the addition of 15 wt% NH2-MIL-53(Al) MOF into the CA matrix resulted in highest enhancement of FFV. Furthermore, MMM loaded with 15 wt% NH2-MIL-53(Al) demonstrated highest CO2 permeability as well as CO2/CH4 and CO2/N2 selectivities of 52.6 Barrer, 28.7 and 23.4, respectively. Besides, the resultant MMM showed CO2 plasticization resistance of up to 30 bar, which is 200% increment in comparison of pristine CA membrane which is only 10 bar. This work also revealed that the resultant MMMs showed significantly higher CO2 separation performance compared to the results previously reported for CA-based MMMs. Thus, it can be concluded that the MMMs fabricated in the present work has potential for CO2 removal from the flue gas and natural gas at industrial scale.

In this research work, polyethersulfone (PES) and polyethersulfone/polyvinyl acetate (PES/PVAc) blend were incorporated with 10 wt.% of TiO2 nanoparticles to form mixed matrix membranes (MMM). FESEM and TGA were utilized respectively to scrutinize the morphology and thermal stability of the developed membranes. Permeation tests of ideal CO2 and CH4 gases were also conducted to assess the separation performance of resultant membranes. The PES/PVAc/TiO2 polymer blend MMM was found to be the most thermally resistant and has the highest CO2 permeability and CO2/CH4 selectivity as compared to the other membranes.

Over the years, functionalization of zeolite is gaining popularity among researchers to further modify the properties of the zeolite for wide applications. The procedure of functionalization is crucial to ensure that the framework and structure of the zeolite would not be destroyed by the functionalization process. In this work, zeolite AlPO-18 was synthesized via hydrothermal synthesis method and functionalized by (3-Aminopropyl) triethoxysilane (APTES). The effect of the APTES functionalization on zeolite AlPO-18 was investigated in this work. Both unfunctionalized and silane-functionalized zeolite AlPO-18 were characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Thermogravimetric analysis (TGA) for their properties. The morphology and the composition of the elements present in zeolite AlPO-18 and zeolite NH2-AlPO-18 were examined using Field Emission Scanning Electron Microscopy (FESEM) and Energy-Dispersive spectroscopy (EDX) respectively. The XRD pattern of NH2-AlPO-18 was similar to that of zeolite AlPO-18, however, the intensity of the peaks was lower compared to zeolite AlPO-18. Based on the FTIR spectra, the presence of N-H stretching and bending vibration band of aminosilane were observed in the NH2-AlPO-18 sample. According to FESEM images, the morphology of NH2-AlPO-18 was comparable to that of zeolite AlPO-18 even after functionalization, proving that functionalization of aminosilane on zeolite does not affect on the zeolite structure. Besides that, EDX proves the presence of 3.02 % of element N in the NH2-AlPO-18 sample which is absent in the zeolite AlPO-18 sample. All of the characterizations evinced the presence of aminosilane, APTES in the NH2-AlPO-18 sample.

In recent years, mixed matrix membranes (MMMs) have received worldwide attention for their potential to offer superior gas permeation and separation performance involving CO2 and CH4. However, fabricating defect-free MMMs still remains as a challenge where the incorporation of fillers into MMMs has usually led to some issues including formation of undesirable interfacial voids, which may jeopardize the gas separation performance of the MMMs. This current work investigated the incorporation of zeolite RHO and silane-modified zeolite RHO (NH2–RHO) into polysulfone (PSf) based MMMs with the primary aim of enhancing the membrane’s gas permeation and separation performance. The synthesized zeolite RHO, NH2–RHO, and fabricated membranes were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared-attenuated total reflection (FTIR-ATR), thermogravimetric analysis (TGA) and field emission scanning election microscopy (FESEM). The effects of zeolite loading in the MMMs on the CO2/CH4 separation performance were investigated. By incorporating 1 wt% of zeolite RHO into the MMMs, the CO2 permeability and ideal CO2/CH4 selectivity slightly increased by 4.2% and 2.7%, respectively, compared to that of a pristine PSf membrane. On the other hand, a significant enhancement of 45% in ideal CO2/CH4 selectivity was attained by MMMs incorporated with 2 wt% of zeolite NH2-RHO compared to a pristine PSf membrane. Besides, all MMMs incorporated with zeolite NH2-RHO displayed higher ideal CO2/CH4 selectivity than that of the MMMs incorporated with zeolite RHO. By incorporating 1–3 wt% zeolite NH2-RHO into PSf matrix, MMMs without interfacial voids were successfully fabricated. Consequently, significant enhancement in ideal CO2/CH4 selectivity was enabled by the incorporation of zeolite NH2–RHO into MMMs.

In this work, zeolite T particles were modified with three different types of silane groups including, 3-Aminopropyltrimethoxysilane (APTMS), N-(2aminoethyl)-3-aminopropyl-trimethoxysilane (AAPTMS) and 3-(2-(2-aminoethylamino) ethylamino) propyltrimethoxysilane (AEPTMS) which contain monoamine, diamine and triamine group, respectively, before incorporated into 6FDA-durene polyimide. The physicochemical properties of the particles and the resultant membranes were characterized using XRD, FESEM, EDX, FTIR, TGA and DSC. The results demonstrated that the incorporation of APTMS modified zeolite T particles into 6FDA-durene polymer matrix failed to improve the interfacial adhesion between filler and polymer phases. This phenomenon subsequently contributes to the reduction of CO2 permeability of 9.3% and decrement of CO2/CH4 selectivity of 29.5% as compared to membrane incorporated with unmodified zeolite T, which showed CO2 permeability and CO2/CH4 selectivity of 844 Barrer and 19.1, respectively. Meanwhile, composite membranes loaded with AAPTMS and AEPTMS modified zeolite T particles have effectively enhanced the filler/polymer interfacial adhesion and separation properties of the membranes. Although the incorporation of AAPTMS zeolite T particles into 6FDA-durene polymer demonstrated 2.7% reduction of CO2 permeability, increment of CO2/CH4 selectivity up to 26.4 was obtained, which successfully lies on Robeson upper limit 2008. Meanwhile, composite membrane embedded with AEPTMS modified zeolite T particles has resulted in the increment of both CO2 permeability and CO2/CH4 selectivity of 857.7 Barrer and 22.5, respectively. Overall, the effect of different amine groups in the modification of zeolite T surface on the performance of the composite membranes has been demonstrated in this work.

Simulation technique has been employed to elucidate the effect of thickness upon confinement to gas transport properties in pure and binary mixtures within ultrathin polysulfone membranes. It is found that the gas diffusivity, solubility, and permeability are improved with increment in membrane thickness, which can be rationalized through bigger free volume in thicker polymeric membranes attributed to diminishing chains relaxation. The effect is found to be exceptionally perceptible in thinner polymeric films beneath 400 A . Accuracy of the simulation methodology has been validated by demonstrating good accordance with actual gas permeability data. As for binary condition, the gas transport properties are demonstrated to be comparatively lower than its pure counterpart due to competitive sorption and barrier for diffusion in the presence of secondary gas molecules. In addition, quantitative re-evaluation of published correlations and establishment of new empirical models have been conducted to associate membrane thickness effect to gas transport characteristics. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 131�158. © 2017 Wiley Periodicals, Inc.

In recent years, there has been a great interest in the production of nanocrystalline cellulose (NCC) due to its excellent properties. In this study, empty fruit bunch (EFB) was used as the material for the production of NCC due to its high cellulose content, inexpensive and readily-available source. NCC was prepared using acid hydrolysis at 62% for 1 hours. The morphology of NCC was determined by Field Emission Scanning Electron Microscopy (FESEM). The size of NCC was less than 50 nm in width. The obtained NCC was also characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). FTIR spectra analysis showed that hemicellulose and lignin were mostly removed from the EFB after bleaching and alkaline pre-treatment. XRD diffractograms revealed that EFB nanocellulose showed a crystallinity improvement of 24.3% compared to raw EFB cellulose.

The performance of a zeolitic imidazolate framework-8 (ZIF-8) membrane in single and binary CO2/CH4 gas separation was investigated by means of a gas transport model that included generalized Maxwell-Stefan and binary friction models. The model concerns gas diffusion through the membrane layer, gas flow through membrane intercrystalline pores, and resistance of the support layer. The effective membrane area considering the actual area for the gas permeated through the membrane was also introduced in this model. The selective ZIF-8 membrane was successfully synthesized using a microwave-assisted solvothermal method on an α-alumina support pre-attached with ZIF-8 seeds by solvent evaporation. The simulated data agreed well with the experimental data. The model revealed that the membrane intercrystalline pores and its effective area significantly affected the CO2/CH4 gas permeation and separation performance.

In this work, the incorporation of ZIF-8 nanofiller for the improvement of the transport properties of 6FDA-durene membrane in CO 2 /CH 4 separation is investigated. Central composite design (CCD) coupled with response surface methodology (RSM) were utilized for the optimization of the separation process variables over ZIF-8/6FDA-durene MMM in CO 2 /CH 4 separation. Three models correlating the independent parameters including, pressure (3.5–12.5 bar), temperature (30–50 °C) and CO 2 concentration (10–90 vol%) with the responses including, CO 2 permeability, CH 4 permeability and CO 2 /CH 4 selectivity were developed based on the experimental data. The optimum parameters for achieving the highest separation performance were obtained at pressure of 4.76 bar, temperature of 30 °C and CO 2 concentration of 90 vol%, which resulted in CO 2 permeability of 687.20 Barrer, CH 4 permeability of 71.03 Barrer and CO 2 /CH 4 selectivity of 8.92. The deviation of the corresponding experimental data was found to be in an acceptable range, confirming the suitability of RSM for predicting the membrane performance and consequently optimizing the separation process variables.