Search

Defect‐engineered metal–organic frameworks (MOFs) with outstanding structural and chemical features have become excellent candidates for specific separation applications. The introduction of structural defects in MOFs as an efficient approach to manipulate their functionality provides excellent opportunities for the preparation of MOF‐based mixed matrix membranes (MMMs). However, the use of this strategy to adjust the properties and develop the separation performance of gas separation membranes is still in its early stages. Here, a novel defect‐engineered MOF (quasi ZrFum or Q‐ZrFum) was synthesized via a controlled thermal deligandation process and incorporated into a CO2‐philic 6FDA‐durene polyimide (PI) matrix to form Q‐ZrFum loaded MMMs. Defect‐engineered MOFs and fabricated MMMs were investigated regarding their characteristic properties and separation performance. The incorporation of defects into the MOF structure increases the pore size and provides unsaturated active metal sites that positively affect CO2 molecule transport. The interfacial compatibility between the Q‐ZrFum particles and the PI matrix increases via the deligandation process, which improves the mechanical strength of Q‐ZrFum loaded membranes. MMM containing 5 wt.% of defect‐engineered Q‐ZrFum exhibits excellent CO2 permeability of 1308 Barrer, which increased by 99 % compared to the pure PI membrane (656 Barrer) at a feed pressure of 2 bar. CO2/CH4 and CO2/N2 selectivity reached 44 and 26.6 which increased by about 70 and 16 %, respectively. This study emphasizes that defect‐engineered MOFs can be promising candidates for use as fillers in the preparation of MMMs for the future development of membrane‐based gas separation applications. [ABSTRACT FROM AUTHOR]

Fluorinated metal–organic frameworks (F-MOFs) as fast-growing porous materials have revolutionized the field of gas separation due to their tunable pore apertures, appealing chemical features, and excellent stability. A deep understanding of their structure–performance relationships is critical for the synthesis and development of new F-MOFs. This critical review has focused on several strategies for the precise design and synthesis of new F-MOFs with structures tuned for specific gas separation purposes. First, the basic principles and concepts of F-MOFs as well as their structure, synthesis and modification and their structure to property relationships are studied. Then, applications of F-MOFs in adsorption and membrane gas separation are discussed. A detailed account of the design and capabilities of F-MOFs for the adsorption of various gases and the governing principles is provided. In addition, the exceptional characteristics of highly stable F-MOFs with engineered pore size and tuned structures are put into perspective to fabricate selective membranes for gas separation. Systematic analysis of the position of F-MOFs in gas separation revealed that F-MOFs are benchmark materials in most of the challenging gas separations. The outlook and future directions of the science and engineering of F-MOFs and their challenges are highlighted to tackle the issues of overcoming the trade-off between capacity/permeability and selectivity for a serious move towards industrialization. [ABSTRACT FROM AUTHOR]

In the present study, zinc ion‐exchanged zeolite Y (ZnY) was incorporated as a dispersed phase into polyphenylsulfone (PPSU) polymer matrix to prepare PPSU/ZnY porous mixed matrix membranes (MMMs) with enhanced separation properties. Various MMMs with different ZnY contents (0, 0.25, 0.5, 0.75, 1, 1.5, and 3 wt.%) were fabricated using phase inversion method. The morphologies of prepared membranes were characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. Fourier transform infrared (FTIR) and X‐ray diffraction (XRD) were used to investigate the chemical structures and microstructural properties, respectively. Differential scanning calorimetry (DSC) analysis and tensile test were done to investigate thermomechanical properties of the membranes. Density and dynamic viscosity of membrane casting solutions as well as porosity, mean pore size, contact angle and water content of the prepared membranes were determined to investigate how these parameters affect the morphology of the membranes. Finally, separation performance of the membrane samples was investigated by determining water flux, salt (CuSO4) rejection, and anti‐fouling properties. SEM results showed an increase in top layer pore volumes with the incorporation of ZnY nanoparticles, which offer a higher water flux. AFM images indicated the higher surface roughness for an MMM compared to the pure PPSU membrane. FTIR spectroscopy confirmed the presence of all PPSU and ZnY functional groups in the MMM and showed no existence of chemical bonds at the polymer‐particle interface. XRD patterns exhibited a decrease in the degree of crystallinity by addition ZnY nanoparticles into PPSU matrix. DSC and tensile tests confirmed the XRD analysis and show lower Tg and tensile stress for an MMM compared to the pure PPSU membrane. Porosity measurements showed that the membrane porosity improved by decreasing the polymer concentration in the casting solutions and by incorporation of ZnY nanoparticles. The contact angle measurement indicated that the values decrease upon loading of ZnY nanoparticles. Finally, an enhanced pure water flux of 4.315 L m−2 h−1 bar−1 and a salt rejection of 75%, respectively as compared to 3.591 L m−2 h−1 bar−1 and 81% for pure PPSU membrane, were observed for the MMM with 1 wt.% of ZnY filler. [ABSTRACT FROM AUTHOR]

In this study, polyetherimide (Ultem) was chosen as a polymeric matrix, and micron‐sized Ni2+‐exchanged nano‐porous NaX zeolite was selected as an inorganic filler to fabricate novel mixed matrix membranes (MMMs) for CO2 separation. Fabricated membranes were evaluated by Differential scanning calorimeter, Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and energy dispersive X‐ray. The influences of filler loading (0–5 wt.%) and feed pressure (2–10 bar) on gas separation properties were surveyed. CO2/N2 ideal selectivity of 3 wt.% NiX loaded MMM (optimum MMM) was increased to 34 (about 36%) compared to 25 for the pristine membrane. Furthermore, CO2 permeability was improved by about 45%, from 1.3 Barrer for the pure membrane to 1.88 Barrer for MMM containing 3 wt.% functionalized filler. These improvements originate from a combination of the inherent surface diffusion mechanism of zeolite X and reversible reaction between free orbitals of transition metal ions (Ni2+) and electron pairs of CO2 molecules. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The development of advanced functional materials is a growing field to improve the performance of mixed matrix membranes (MMMs) as energy efficient alternatives to the conventional gas separation membranes. Herein, a novel highly selective host–guest complex was synthesized by encapsulating a Schiff base macrocyclic copper complex in the FAU super-cages of zeolite 13X. The design strategy of the encapsulated complex is based on the utilization of the same polymer's monomer, durene diamine monomers, as the Schiff base ligand component to eliminate interfacial defects, and also improve the CO2-facilitated transport through the favorable functional groups. MMMs comprised of ([Cu(6L)]2+@13X) and the as-synthesized 6FDA-durene polyimide were investigated. The MMM containing 15 wt% of the [Cu(6L)]2+@13X complex resulted in the CO2 permeability of 1034.1 barrer with CO2/CH4 and CO2/N2 selectivities of 42.2 and 38.3, respectively. These results are 127%, 173% and 173% higher than that of the pristine 6FDA-durene, which showed the CO2 permeability of 455.2 barrer with CO2/CH4 and CO2/N2 selectivity of 15.4 and 14.0, respectively. Thus, the superior results of the present work suggest that encapsulated Schiff base transition metal complexes containing polymeric matrix monomers offer a new route to produce advanced functional fillers for highly effective gas separation MMMs. [ABSTRACT FROM AUTHOR]

Summary: In this study, a two‐dimensional mathematical model is proposed for modeling the hollow fiber membrane (HFM) separators for hydrogen (H2) recovery unit implemented in the Razi Petrochemical Company (Imam Khomeini Port, Iran) to capture hydrogen from ammonia (NH3) purge gas. In this regard, computational fluid dynamics is applied to solve the equations of momentum and mass transfer in the laminar flow conditions. Axial and radial diffusion for mass transfer inside the membrane fibers and axial diffusion within the shell side of separator were considered. The distributions of concentration, velocity, and mass transfer fluxes were achieved by the model. As the new insights, the effects of feed flow rate and feed gas concentration on mass transfer of H2 were investigated. Moreover, fluid velocity profile and H2 fluxes in the tube (fiber), membrane, and shell sides of the HFM separator were studied. The results of simulation were compared with the industrial data and showed that the present developed model has excellent agreement with the experimental data with a low mean deviation value of 3.5%. [ABSTRACT FROM AUTHOR]

Commercial poly (ether-block-amide) (Pebax®) copolymers are thermoplastic elastomers that have attracted attention as membrane materials due to their high performance in CO2 separation. In this study, a cross-linking reaction is reported as a viable strategy to improve the gas separation performance of a highly permeable but low selective Pebax 2533 membrane. To this end, a new bi-functional aminosilane cross-linker (3-aminopropyl(diethoxy)methylsilane (APDEMS)) was applied. Cross-linked Pebax 2533 membranes were prepared via solution-casting with different amounts of APDEMS ranging from 0.5 to 4 wt%, to investigate the effect of the aminosilane concentration on the membrane performance. Gas separation with prepared membranes was studied for CO2/N2 at the feed pressure ranges of 2-10 bar. Instrumental analyses were applied to investigate the effect of the cross-linking reaction on the structure and properties of the membranes. The results showed that a 2 wt% APDEMS cross-linked Pebax 2533 membrane has the best gas separation performance. The CO2/N2 ideal selectivity of the cross-linked Pebax 2533 increased twice compared to the neat Pebax 2533 membrane at the feed pressure of 2 bar, while the CO2 permeability experienced a slight decrease by cross-linking, but still remains higher than the permeability of other Pebax grades. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Polyimides (PIs) are an important, well-established, and commercialized class of polymers due to their extraordinary physical and chemical properties. They have been extensively applied as membrane fabrication materials for gas separation, especially in natural gas upgrading and acidic CO 2 gas removal from industrial off-gases. However, two major unsolved challenges still remain for PI-based membranes: overcoming the trade-off relationship between the gas permeability and selectivity, and maintaining the long-term operational performance through controlling thermal and pressure conditioning, physical and chemical ageing, plasticization, swelling, permeation hysteresis, and resistance against impurities or presence of trace contaminants. This review aims to explore practical procedures to give the best insights into synthesis of efficient PI-based gas separation membranes as well as introducing advanced modification methods that have been applied for available PIs in view of obtaining a superior performance. A comprehensive "structure-to-property" relationship is elaborated by molecular design and engineering of PI monomers, i.e., the assembly of sub-objects: diamine and dianhydride monomers. This approach covers all issues from atom, functional group, segment (micro-structure or molecular design) to branch, chain and network assembly of the PIs. Detailed discussions include substitution positions, halogenated groups, bridging functional groups, bulky groups (linear and branched and subdivided into silyl and germyl, fluorine, methyl, iptycene and Tröger's Base groups). Moreover, criteria for designing high quality hyperbranched polyimides (HB-PI), co-polyimides (co-PIs) including polyamide-imides, polyether-imide, triptycene based co-PIs, multi-block co-PIs, and hyper-branched co-PIs are presented. Cross-linked PIs are also discussed by classifying them according to the methods of reaction: thermal, UV, and chemical cross-linking (abbreviated by TCL, UVCL, and CCL, respectively). An additional issue in this regard, i.e., the hyper cross-linked polyimides, HCLPs, is discussed as well. [ABSTRACT FROM AUTHOR]

Abstract A novel high-performance mixed matrix membrane (MMM) with a low amount (< 2 wt%) of filler loading was fabricated in which the synthesized copper nanoparticles (Cu) incorporated into a glycerol-modified poly(ether- block -amide) (Pebax 1657, Pe). Glycerol (Gl) as an affordable low molecular weight additive provides a good CO 2 affinity. On the other hand, the presence of Cu nanoparticles improves CO 2 permeability through a facilitated transport mechanism, with destruction of the well-packed polymer chain structure and breaking the hydrogen-bond between Gl and Pe chains. First, pure Pe membrane was modified by adding different amounts of Gl (0–25 wt%). The optimum membrane (Pe/Gl (15 wt%)) was determined by measuring the CO 2 /N 2 gas permeation properties. It was shown that the selectivity was dramatically increased (~ 172%) from 81.9 (for pure Pe) to 222.7 (for Pe/Gl (15 wt%)), while a fairly significant decrease (over 23%) in CO 2 permeability (from 65.71 for pure Pe to 50.42 for Pe/Gl (15 wt%)) was obtained at 25 °C and 10 bar. Second, the synthesized Cu nanoparticles were embedded (0–2 wt%) into the Pe/Gl (15 wt%) matrix to fabricate the Pe/Gl/Cu MMMs. The results revealed that Pe/Gl (15 wt%)/Cu (1.5 wt%) membrane has a higher permeability (63.6 Barrer, 25 °C and 10 bar), and to some extent a lower selectivity (200) in comparison with the Pe/Gl (15 wt%) membrane. However, it presents an approximately similar permeability but a distinct increase (144%) in selectivity compared to the pure Pe. Accordingly, a series of high-performance Pe/Gl/Cu MMMs were fabricated which surpassed the Robeson's upper limit and can be as the promising membranes for CO 2 separation. Graphical abstract fx1 Highlights • Novel ternary mixed matrix membranes (MMMs) synthesized for CO 2 /N 2 separation. • An affordable low molecular weight additive, the glycerol (Gl), blended with Pebax. • Synthesized copper (Cu) nanoparticles added in low amounts (< 2 wt%) to the matrix. • The Pebax/Gl/Cu ternary MMMs showed superior CO 2 /N 2 separation performance. [ABSTRACT FROM AUTHOR]

In order to calculate the permeability of gases in mixed matrix membranes (MMMs) filled with porous particles, the first step is to calculate the permeability of filler particles. Because particle pore sizes of the considered sodium zeolite Y (NaY) in this study is greater than the molecular sizes of the tested gases (CO2 and N2), it is assumed that diffusion of the gases in the zeolite particles is from Knudsen type. Moreover, the gas sorption data (isotherms) were measured experimentally and then fitted with Langmuir and Freundlich model equations to calculate the related constants. Finally, the experimental CO2 and N2 permeabilities of cellulose acetate (CA)/NaY MMMs were compared with the corresponding data predicted by the well‐known permeability models in this field. It was concluded that the Bruggeman model has better predictions among the other models, especially for the higher particle loadings. POLYM. COMPOS., 39:4560–4568, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Activated carbon (AC) was impregnated with titanium dioxide (TiO2) to synthesize AC/TiO2 nanocomposite through the sol-gel method at 400°C. Nanocomposite characterization was conducted by XRD, SEM and FTIR analyses. The synthesized nanoparticles were phase-pure anatase nanocrystallites with the average size of 10 nm. The AC/TiO2 nanocomposites were applied for the first time to photocatalytic decomposition of Congo red (CR) dye under ultraviolet (UV) irradiation in a photoreactor. The effects of AC/TiO2 nanocatalyst dosage (0.3–1 g), CR concentration (20–100 ppm), pH (3–9) and temperature (30–50°C) were examined for removal of CR solution pigments. Moreover, the adsorption kinetics and isotherm models were investigated on the AC and synthesized AC/TiO2 nanophotocatalyst. The adsorption mechanism was found to be a pseudo-second-order kinetics with the good agreement for both adsorbents. Also the experimental isotherms were appropriately described by the Langmuir and Temkin models for AC adsorbent and AC/TiO2 nanocomposite, respectively. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid nanocomposites within polymeric matrices have potential as functional materials for membrane gas separation. We present a new synthesis strategy for preparing novel hybrid host–guest nanocomposites by encapsulating a metal–organic complex of a transient metal such as cobalt (Co) in zeolite Y cavities with the ship-in-a-bottle (SIB) synthesis method. Then, the encapsulated zeolite Y nanoparticles were embedded into the Matrimid® 5218 matrix to fabricate a novel type of mixed-matrix membranes (MMMs) for gas separation. Eventually, the effects of incorporating these types of synthetic fillers on CO2/CH4 permselectivity of MMMs were comprehensively studied. Incorporating an encapsulated polyaza macrocyclic Co–ligand complex into the polymer matrix endowed the resultant MMM with brilliant CO2 separation performance, together with an unusual/extremely desirable enhancement in CO2/CH4 selectivity. Indeed, MMM with 15 wt% encapsulated filler loading at 35 °C and 2 bar experienced a CO2 permeability of about 18.96 barrer and CO2/CH4 selectivity of about 111.7, which were more than two- and three-fold that of pure Matrimid performance. The proposed new method opens a new window to fabrication of purposeful MMMs for specific separation opportunities. [ABSTRACT FROM AUTHOR]

In the current research, simulation of chemical oxygen demand (COD) removal process from a high saline refinery wastewater using a membrane bioreactor equipped with a hollow fiber membrane, named as a hollow fiber membrane contactor (HFMC) was investigated using computational fluid dynamics method. A two-dimensional mathematical model was proposed to investigate COD transfer. This model describes the diffusion in the axial and radial directions of the HFMC. The model also examines the momentum transfer toward the tube and the shell. Comparing the model results with the experimental data, a deviation of 7.35% attained which reflects the proper reliability of the proposed model to predict the absorption of COD in the HFMC. [ABSTRACT FROM AUTHOR]

The kinetics of sucrose hydrolysis by invertase was studied in order to find a comprehensive model for the reaction pathway and mechanism. First, three common models of Michaelis-Menten (MM), substrate inhibition (S2), and substrate clusters' inhibition (S3(I)) were investigated. The third model was found to better predict the initial sucrose concentration. Then, the S3(I) model was modified to cover the remaining pathway (S3(II)). Finally, a new comprehensive model (S3(III)) was evaluated, which in addition to what is considered in the two previously mentioned models (S3(I) and S3(II)) also involved the initial time lag. The model predictions showed an excellent agreement with the experimental data. The mean absolute error for the MM model is significantly reduced for the S3(III) model. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the fabrication and evaluation of a new mixed matrix membrane for CO2/N2 separation. Micro-sized nano-porous sodium zeolite-Y (NaY zeolite) particles (0-25 wt.%) were incorporated into the dense (homogeneous) cellulose acetate (CA) membrane to prepare the CA/NaY mixed matrix membranes. One of the most important features of this study is to explore the simultaneous effect of annealing and particle loadings on the morphology and gas permeation properties of the prepared membranes. The membranes were characterized by Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) and scanning electron microscopy (SEM) analyses. Also, the CO2/N2 separation performance of the membranes was evaluated by single gas permeation measurements. The results showed that annealing causes a considerable improvement in the morphology of the CA and the related mixed matrix membranes. Additionally, more than a two-fold increase in CO2 permeability with no considerable decrease in CO2/N2 selectivity was achieved by a 20 wt.% NaY loading into the CA membrane. The results of investigating the effect of pressure (4-22 bars) on CO2 permeability showed a reduction in the CO2-induced plasticization of glassy CA with a significant shift in the plasticization pressure toward higher values. The introduction of NaY zeolite in the annealed CA membranes, shifted the plasticization pressure from 12.76 to 16.86 bars when the zeolite loading was changed from 0 to 25 wt.%. [ABSTRACT FROM AUTHOR]

The toxicity of phenol even at low concentrations in industrial effluents is high enough to meet its needs for separation. In this paper, a review will be carried out on the traditional techniques and recent advances in the separation of phenol from its contaminated streams. The most commonly used methods classified based on the phenol concentrations (high, medium, and low), and also, their advantages and disadvantages that should be considered in the design of industrial wastewater treatment systems will be discussed. Finally, the best methods will be suggested for each concentration range at the influent and, of course, that is allowable in the final effluent. The survey results recommended that biodegradation, chemical, electrochemical, and photocatalytic oxidation, solid phase extraction, ozonation, reverse osmosis/nanofiltration, and wet air oxidation are useful methods in low phenol concentrations, whereas liquid–liquid extraction, pervaporation, membrane-based solvent extraction, adsorption, and distillation are suggested for high phenol concentrations. [ABSTRACT FROM AUTHOR]

Global climate change, its present control and even its future reduction have been considered. Energy has been proposed as the main feed of comprehensive development. The way for meeting energy needs which certainly affects the existing energy resources will have forceful climate consequences. The purpose of this study is to explore how, in practice, the energy requirements of sustainable development can be afforded without any climate-change aggravation. Two fundamental approaches were proposed and completely discussed: the first long-term developing approach is the use of advanced energy-productive technologies instead of the existing ones and/or implementation of hybrid processes, a combination of conventional systems with a newly low energy-consumptive and emission-reductive technology in a newly installed system. The second most sustainable scheme is the development of alternative renewable energy (RE) resources. In this case, available internationally legal documents discovering the RE policies were explored and their commitment strategies were taken into original and deliberate challenges. It was concluded that the best solution to afford energy requirements is the expansion of RE sources, excluding or rarely without any sanctions reflected on the main documents of international climate policy. Since the dominant conditions of international investments have more tendencies to the short-time cost-efficient methods, the documents have only provided a limited situation for the expansion of REs. As a result, the present weak status of REs in the documents comprises their attitude towards the long-term developing scheme (the first approach) and not to the most sustainable scheme of altering the energy resources (the second approach). [ABSTRACT FROM PUBLISHER]

Polymeric membranes were prepared by blending different grades of poly(ethylene glycol) (PEG) as the added polymer with acrylonitrile-butadiene-styrene as the backbone structure. The membranes were characterized by Fourier transform infrared, X-ray diffractometry, dynamic mechanical thermal analysis, differential scanning calorimetry, and scanning electron microscopy. Furthermore, the gas permeation and separation properties of CO2/CH4 were studied. In addition, the effect of pressure (1-8 bar) and the effect of PEG content (0-40 wt%) on CO2 and CH4 permeability/selectivity were investigated. The results showed that, in more cases, with the introduction of PEG molecules, CO2/CH4 selectivity increases without significant changes in CH4 permeability, indicating that the incorporation of intermolecular interaction is suitable for the separation of gas pairs with no molecular size domination but the solution-diffusion. From the viewpoint of gas separation applications, the resultant data are in the commercially attractive region. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: A mathematical model was developed for a two-dimensional transient nitrate transport through an extractive membrane bioreactor (MBR) with a hollow-fiber membrane module which is used in the denitrifying system of drinking water. Denitrification takes place on the shell side of the membranes, creating a driving force for a mass transfer. The presented CFD model formulates and solves the couples of fundamental mass and momentum balance equations using numerical techniques. Simulation results showed that with an increase in feed flow rate, MBR efficiency decreases. Moreover, MBR efficiency increases as the feed concentration rises. In addition, when the effect of membrane structural parameters was investigated; it was shown that the restrictive factor, Kr, has a distinctive effect on MBR efficiency. Besides, using three correlations to estimate the tortuosity as a function of porosity, the effect of porosity was examined and it demonstrated that MBR efficiency was affected by a low value of 2.8% difference in the standard deviations of these three correlations. Finally, the simulation results demonstrate that the model is a good predictive one, especially from the hydrodynamics point of view. Comparing the simulation results with the experimental data, a reasonable conformity with deviations of smaller than 8.00% was achieved. [Copyright &y& Elsevier]

Abstract: CO2 removal from different gas streams via the polymeric membranes has been propounded as an important issue in greenhouse gas emissions control, natural gas upgrading, and enhanced oil recovery. Here, polymeric blend membranes were prepared from acrylonitrile–butadiene–styrene (ABS) and poly vinyl acetate (PVAc), and their CO2/N2 and CO2/CH4 separation characteristics were investigated. The influence of different PVAc contents on gas separation performance and the effect of pressure, ranging from 1 to 8bar, on CO2 permeability were studied. Furthermore, the morphology of the membranes was analyzed by FTIR, XRD, DSC and SEM. It was shown that the highest CO2 permeability of 5.72 Barrer for the membrane containing 10wt.% PVAc, the highest CO2/CH4 selectivity was 29 in 20wt.% PVAc and CO2/N2 was 40.41 in 30wt.% PVAc contents. These results comprised from different effective factors such as PVAc acetate polar groups, compactness in polymer matrix at the presence of high molecular weight PVAc, and the acrylonitrile and flexible butadiene contents of ABS. Furthermore, in the transmembrane pressure of 2–8bar the CO2 permeability approximately descended with the pressure increase for PVAc content of 0–40wt.%, and it ascended for 50–60wt.%. Generally, the prepared membranes can be taken into account as better membranes for CO2/N2 separation than CO2/CH4. [Copyright &y& Elsevier]

Carbon dioxide capture and storage (CCS) has been propounded as an important issue in greenhouse gas emissions control. In this connection, in the present article, the advantages of using polymeric membrane for separation of carbon dioxide from CO2/N2 streams have been discussed. A novel composition for fabrication of a blend membrane prepared from acrylonitrile-butadiene-styrene (ABS) terpolymer and polyethylene glycol (PEG) has been suggested. The influence of PEG molecular weight (in the range of 400 to 20000) on membrane characteristics and gas separation performance, the effect of PEG content (0-30 wt%) on gas transport properties, and the effect of feed side pressure (ranging from 1 to 8 bar) on CO2 permeability have been studied. The results show that CO2 permeability increases from 5.22 Barrer for neat ABS to 9.76 Barrer for ABS/PEG20000 (10 wt%) while the corresponding CO2/N2 selectivity increases from 25.97 to 44.36. Furthermore, it is concluded that this novel membrane composition has the potential to be considered as a commercial membrane. [ABSTRACT FROM AUTHOR]

In this paper, novel membranes were prepared from blending the ethylene vinyl acetate (EVA), containing 28 wt.% of vinyl acetate, and poly(ethylene glycol) (PEG) (0-20 wt.%) with molecular weights of 200, 1000, and 1500, and considered for CO2/N2 separation over the feed pressure of range 2-8 bar. Physical properties and the morphology of the membranes were evaluated by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses in order to justify the gas permeation and separation performance of the membranes. The results showed that CO2 permeability increases by increasing the PEG content of the blend membranes. However, increasing PEG loading enhanced CO2/N2 selectivity just for the blends containing up to 10 wt.% of PEG and it decreased at higher PEG loadings. The PEG with a molecular weight of 200 showed a more efficient gas separation performance due to its effective role in providing amorphous regions in the blends. Furthermore, higher CO2 permeabilities were obtained at higher feed pressures. The selectivity increased by increasing the feed pressure for neat EVA, EVA/5 wt.% PEG and EVA/10 wt.% PEG membranes, but it had no significant effect on the selectivity of the samples with 15 and 20 wt.% of PEG.© 2015 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

A new facilitated transport ionomer membrane was prepared by incorporating Co(II) ions, as fixed carrier, into the sulfonated ethylene-propylene-diene terpolymer, Co(II)-S-EPDM, and was applied for preferential transport of carbon dioxide rather than nitrogen from CO 2 /N 2 gas streams. The membranes were also characterized by using the FTIR, SEM and TG/DSC analyses. Furthermore, single gas permeation experiments at different membrane thicknesses (30 and 200 μm), sulfonic group contents (0.1 and 0.2 mmol of sulfonic acid (SO 3 H)/g EPDM), feed gas pressures (2–10 bar) and temperatures (30–50 °C) were carried out. The permeation results of the dense Co(II)-S-EPDM ionomer membranes show that the incorporation of Co(II) ions into the sulfonated EPDM ionomers increases the permeance of both CO 2 and N 2 gases. Moreover, due to facilitated CO 2 transport by the carriers, the CO 2 /N 2 selectivity is also increased. These are mainly attributed to the formation of polymer coordinate complexes in the ionomer. [ABSTRACT FROM AUTHOR]

The presence of copper in aquatic environment is a serious threat for human health and ecosystem conservation. Adsorption is a powerful, operable and economic method for remediation of copper ions from aqueous phase. Carbohydrate biopolymers have emerged as promising, effective and environmental-friendly adsorbents for copper remediation. In part A of this review, different types of carbohydrate biopolymer adsorbents were surveyed focusing on prevalent and novel synthesis and modification methods. In current work (part B of the review), isothermal, thermodynamic and kinetic aspects of the copper adsorption by carbohydrate-based adsorbents as well as the regeneration and reusability of the biopolymer adsorbents are overviewed. Adsorption capacity, time required for equilibrium (adsorption rate), thermal-sensitivity of the adsorption, favorability extent, and sustainability of the adsorbents and adsorption processes are valuable and useful outcomes, resulted from the thermokinetic and reusability investigations. Such considerations are critical for the process design and scale up regarding technical, economical and sustainability of the adsorption process. Mono-layer versus multi-layer adsorption and EDTA as a potential eluting agent for copper ion extraction from biopolymer adsorbent network. Unlabelled Image • Isotherms, kinetics and reuse of carbohydrate biopolymer adsorbents were surveyed. • Adsorption rate, capacity and thermal-sensitivity are essential for process design. • Regenerability and reuse are crucial from economic and environmental viewpoints. • Zeolites and clays highly affect the adsorption features of chitosan composites. [ABSTRACT FROM AUTHOR]

Copper is one of the most toxic heavy metals which must be eliminated from aqueous environments, according to the environmental standards. Carbohydrate biopolymers are promising candidates for synthesizing copper-adsorbent composites. It is due to unique properties such as having potential adsorptive functional sites, availability, biocompatibility and biodegradability, formability, blending capacity, and reusability. Different types of copper-adsorbent carbohydrate biopolymers like chitosan and cellulose with particular focus on the synthesizing and modification approaches have been tackled in this review. Composites, functionality and morphological aspects of the biopolymer adsorbents have also been surveyed. Further progress in the fabrication and application of biopolymer adsorbents would be achievable with special attention to some critical challenges such as the process economy, copolymer and/or (nano) additive selection, and the physicochemical stability of the biopolymer composites in aqueous media. Unlabelled Image • Different types of biopolymers for copper adsorption were overviewed. • Chitosan and cellulose were the most widely-used biopolymers for Cu adsorption. • Various techniques for modification of biopolymer adsorbents were surveyed. • Grafting and composite formation techniques surpassed for biopolymer modification. [ABSTRACT FROM AUTHOR]

Defect-engineered metal-organic frameworks (MOFs) with outstanding structural and chemical features have become excellent candidates for specific separation applications. The introduction of structural defects in MOFs as an efficient approach to manipulate their functionality provides excellent opportunities for the preparation of MOF-based mixed matrix membranes (MMMs). However, the use of this strategy to adjust the properties and develop the separation performance of gas separation membranes is still in its early stages. Here, a novel defect-engineered MOF (quasi ZrFum or Q-ZrFum) was synthesized via a controlled thermal deligandation process and incorporated into a CO 2 -philic 6FDA-durene polyimide (PI) matrix to form Q-ZrFum loaded MMMs. Defect-engineered MOFs and fabricated MMMs were investigated regarding their characteristic properties and separation performance. The incorporation of defects into the MOF structure increases the pore size and provides unsaturated active metal sites that positively affect CO 2 molecule transport. The interfacial compatibility between the Q-ZrFum particles and the PI matrix increases via the deligandation process, which improves the mechanical strength of Q-ZrFum loaded membranes. MMM containing 5 wt.% of defect-engineered Q-ZrFum exhibits excellent CO 2 permeability of 1308 Barrer, which increased by 99 % compared to the pure PI membrane (656 Barrer) at a feed pressure of 2 bar. CO 2 /CH 4 and CO 2 /N 2 selectivity reached 44 and 26.6 which increased by about 70 and 16 %, respectively. This study emphasizes that defect-engineered MOFs can be promising candidates for use as fillers in the preparation of MMMs for the future development of membrane-based gas separation applications., (© 2024 Wiley-VCH GmbH.)