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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]

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]

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]

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]

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]

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]