Preparation Of Mixed Matrix Membranes Research Articles

PVA/PES-amine-functional graphene oxide mixed matrix membranes for CO2/CH4 separation: Experimental and modeling

In this study graphene oxide (GO) was functionalized using amine and used as inorganic filler for preparation of mixed matrix membranes (MMMs) using polyethersulfone (PES) as polymer matrix. These membranes were applied for separation of CO2 from CH4. The effects of filler loading, feed temperature and feed pressure on CO2/CH4 selectivity of the MMMs were investigated. The results indicated that addition of amine-functional graphene oxide in the casting solution enhanced the membrane gas permeance and CO2/CH4 ideal selectivity. SEM images and FTIR analysis were used to characterize the filler particles and the synthesized membranes. SEM images also indicated that, there were appropriate distribution particles in the polymer matrix. Among different types of artificial neural networks (ANN), radial basis function (RBF) network was used to model performance of the MMMs. For training of the RBF model, 70% of the collected experimental data was used and the model was tested using the rest 30% data. The mean square error (MSE) and correlation coefficient (R) were used for investigating performance of the RBF model. The results showed that the RBF model is suitable and efficient for predicting performance of the PES/amine-functional graphene oxide (AFGO) MMMs.

Copoly(alkyl ether imide) membranes as promising candidates for CO2 capture applications

Abstract To improve gas separation properties of membranes, the current research trend is to design mixed matrix membranes using various types of nanoparticles. But to be efficient, such particles must be used with already highly selective (α > 40), highly permeable polymeric matrixes (P > 100 Barrer). In that context, we report the results obtained with a series of copolyetherimide polymers (PEI). This polyimide series has two main advantages: it exhibits a high CO2 selectivity associated to a rubbery copolymer. Thus it has the basic requirements to be a good polymer matrix for the preparation of mixed matrix membrane. This new series was prepared with different types of polyoxyether blocks (PEO) using several aromatic monomers and diamines containing polyethyloxide and polypropyloxide moieties. Permeability measurements showed that the membranes with an ether content of 80% exhibited permeabilities of 622 and 14 Barrer for CO2 and N2, respectively, giving rise to a high ideal selectivity of CO2 over N2 (α = 44). The introduction of the propyl side groups in PEI led to linear increases in the permeability when the PEO content was increased. This trend was observed because the presence of propyl groups prevents the crystallization of PEO chains, as often reported in the literature for PEO-based membranes.

Optimization of PES/ZnO mixed matrix membrane preparation using response surface methodology for humic acid removal

The application of response surface methodology (RSM) in preparation and optimization of membranes is important in order to reduce the effort and time needed to achieving an optimum performance. RSM was used to develop an optimum polyethersulfone (PES)/ZnO mixed matrix (MM) membrane for humic acid removal. The MMs were synthesized by dispersing various amounts of hydrophilic ZnO nanoparticles (NPs) into a solution containing PES, polyvinylpyrrolidone (PVP) and dimethylacetamide (DMAc). Flat sheet MM membranes were prepared via the phase inversion method using the central composite design (CCD). The effects of four preparation parameters, such as PES, ZnO, PVP weight percentages and solvent evaporation time, were investigated. Pure water flux (PWF), humic acid flux (HAF) and humic acid rejection (HAR) were selected as a model responses. It was shown that PES and PVP were mainly affected on both PWF and HAF. Furthermore, the interaction effect between PES and ZnO-NPs shows a significant effect on PWF, while the quadratic effects of both solvent’s evaporation time and ZnO-NPs weight percentage coupled with the interaction effect between PES and PVP weight percentage shows the most significant parameters that affects HAR. The optimization method was subjected to maximize all of the PWF, HAF and HAR. It was also determined that the optimized membrane can be synthesized from a solution containing 17.25 wt% PES, 3.62 wt% ZnO and 3.75 wt% PVP with 15 s of solvent evaporation time. The optimum values of PWF, HAF and HAR were 222.3 (L/m2 h), 94.7 (L/m2 h), and 96.34%, respectively. Thus, it can be concluded that the CCD technique is capable of optimizing PES-ZnO membrane performance.

MOF-mixed matrix membranes: Precise dispersion of MOF particles with better compatibility via a particle fusion approach for enhanced gas separation properties

Mixed matrix membranes (MMMs) incorporating conventional fillers frequently suffer from insufficient adhesion between the polymer matrix and the fillers. This often results in the formation of non-selective voids at the filler/polymer interface, which decreases the performance of the membrane. A novel approach is presented here to develop metal organic framework (MOF) based MMMs by using the self-assembly of MOF and polymer particles followed by their controlled fusion. MOF-polymer interaction is optimized through this strategy and it overcomes MOF-polymer incompatibility, MOF agglomeration and MOF distribution problems, happening especially at high loadings of MOFs when applying conventional methods. Matrimid® polymer particles were first prepared by precipitating a Matrimid® polymer solution in water. The surface of these particles was then modified by the introduction of imidazole groups, enhancing the chemical compatibility with the selected ZIF-8 MOF. ZIF-8 nanoparticles were then grown in-situ to this modified polymer particle suspension by addition of the precursor for ZIF-8 synthesis. The resulted suspension was cast to dryness and annealed in a solvent–vapor environment to induce particle fusion, leading to a dense MMM structure. Scanning electron microscopy (SEM) images showed an excellent dispersion of the ZIF-8 nanoparticles forming a percolating pathway without any agglomeration, even at 40wt% loading of the ZIF-8. Excellent dispersion of ZIF-8 and an excellent ZIF-8-polymer interfacial adhesion resulted in a significant improvement in both CO2 permeability and CO2/CH4 selectivity. The CO2 permeability of the MMMs increased by 200% and the CO2/CH4 selectivity increased by 65% as compared to unfilled Matrimid®. More detailed analysis of the gas transport performance of the MMMs showed that the CO2 permeability and the CO2/CH4 selectivity are mainly governed by the increase in CO2 diffusivity. The presented approach is a very versatile MMM preparation route, not only for this specific ZIF and polymer but for a wide range of material combinations.

Synthesis and gas transport performance of MIL-101/Matrimid mixed matrix membranes

Mixed matrix membranes (MMMs) are composites of highly selective fillers within a polymeric matrix, resulting in higher selectivity and/or flux in gas separation applications. In this work, micron sized MIL-101 crystals with potential of gas separation by adsorption were synthesized and used as filler for the preparation of MMMs for gas separation. Gas adsorption measurements were performed for CO2, CH4 and N2 using MIL-101 crystals and the results showed significant adsorption of CO2 compared with the two other gases at different pressures. SEM images and XRD analysis were used to characterize the filler particles and the synthesized membranes. MIL-101/Matrimid MMMs were synthesized with up to 30wt.% loading of filler particles. SEM images showed good dispersion of the particles in the polymeric matrix and also good adhesion between the filler particles and the polymer. Permeability measurements were performed for pure gases of CO2, CH4 and N2 and the results showed improved CO2/CH4 and CO2/N2 ideal selectivities for the MMMs compared with those for the neat Matrimid membrane. For the MMMs with 10wt.% loading, permeability of CO2 was found as 6.95 Barrer and ideal selectivities for CO2/CH4 and CO2/N2 were as 55.77 and 52.92, respectively.

Polymer functionalization to enhance interface quality of mixed matrix membranes for high CO2/CH4 gas separation

Hydroxyl-functionalized homo- and co-polyimides 6FDA–(DAM)x–(HAB)y (with x : y molar ratio of 1 : 0; 2 : 1; 1 : 1; 1 : 2) and two metal–organic frameworks (MOFs), MIL-53(Al) and NH2-MIL-53(Al) were synthesized for preparation of mixed matrix membranes (MMMs).

Beyond the H2/CO2upper bound: one-step crystallization and separation of nano-sized ZIF-11 by centrifugation and its application in mixed matrix membranes

Nano-sized ZIF-11 with similar features to ZIF-11 has been used for the adsorption of H2and CO2and in the preparation of mixed matrix membranes for H2/CO2separation.

Insight into ETS-10 synthesis for the preparation of mixed matrix membranes for CO2/CH4 gas separation

An in-depth study into the synthesis of the titanosilicate ETS-10 has been carried out to obtain crystals with different particle sizes, roughness and porosity.

Novel carbon nano-fibers (CNF)/polysulfone (PSf) mixed matrix membranes for gas separation

Mixed matrix membranes (MMM) included of carbon nanofibers (CNFs) fabricated and characterized for gas separation performance. For preparation of MMM, carbon nanofibers content was varied from 0.01 to 1wt% in polysulfone (PSf) casting solution. The fabricated CNFs/PSF MMMs characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), ATR–FTIR spectra and pure gas permeation and sorption test. The gas transport properties of MMM measured using single gas permeation set up (N2, O2, CO2, and CH4) at ambient temperature and different feed pressures. Additionally, sorption isotherms for mixed matrix membranes made for CH4 and CO2. The sorption data were analyzed by the dual-mode sorption model. The morphological studies show that the incorporation of CNFs appreciably changed the surface properties of membranes. The permeation test showed that the mixed matrix membrane exhibited high permeability. With increasing CNF concentration, CNFs/PSF membrane permeability raised from 2.134 to 12.04 Barrer for CO2. The results found that this unique membrane had increased permeability and enhanced selectivity. Also it has a great potential to be used practically in gas separation technology.

Functionalization with amine-containing organosilane of mesoporous silica MCM-41 and MCM-48 obtained at room temperature

Functionalized ordered MCM-41 and MCM-48 materials have been obtained by a post-grafting method using 3-aminopropyltrimethoxysilane (APS) as modifying agent. The dependence of APS concentration, and reaction time on average pore size, grafted APS content, pore volume, superficial area, and morphology was studied. The modified silicas were characterized by powder X-ray diffraction (XRD), infrared spectroscopy (FT-IR), transmission electron microscope (TEM) and nitrogen adsorption–desorption experiments. MCM-41 appeared to be more prone to pore blockage than MCM-48 in the grafting procedure. According to the TEM results, no morphological changes were observed in the modified MCM-41 and MCM-48 silicas by comparing with bare silicas. These amine-grafted silicas could have potential application to be used as adsorbents of CO2 in the natural gas sweetening process or as fillers in the preparation of mixed matrix membranes.

A facile route to the preparation of mixed matrix polyvinylidene fluoride membranes with in-situ generated polyethyleneimine particles

The development of mixed matrix polymeric membranes with embedded functional particles/nanomaterials has been an active area of research during the last two decades. Such membranes are being designed to carry out multiple functions (e.g. retention, sorption and catalysis) with improved properties and performance over those of commercial membranes. Polymeric particles could provide greater flexibility for the preparation of mixed matrix membranes with improved particle–matrix compatibility, particle loading, flux and permselectivity. In this article, we describe a facile and simple route to the preparation of mixed matrix polyvinylidene fluoride (PVDF) membranes embedded with branched polyethylenimine (PEI) particles. The critical step of our novel methodology is the in-situ generation of crosslinked PEI micro/nanoparticles (with diameters ranging from 400nm to 3μm) in the membrane casting solution using epichlorohydrin as crosslinker. This eliminates the need to utilize inverse emulsion polymerization techniques to synthesize PEI particles prior to the membrane casting. Using non-solvent induced phase separation (NIPS), we successfully prepared mixed matrix PVDF membranes with uniform particle distribution and PEI particle loadings ranging from 27 to 48wt%. Our novel membrane preparation route exhibits many advantages including simplicity, scalability and versatility. Preliminary experiments show that our new mixed matrix PVDF membranes with embedded PEI particles can serve as weak-base membrane absorbers for proteins such as bovine serum albumin.

Mixed matrix membranes based on 3‐aminopropyltriethoxysilane endcapped polyimides and silicalite‐1

AbstractTo improve membrane permeability and the quality of the polymer‐zeolite interface such that the separation factor is maintained or enhanced, we adopted a novel approach to the preparation of mixed matrix membranes (MMMs). Our approach involved endcapping polyamic acid (PAA) with the coupling agent 3‐aminopropyltriethoxysilane (APTES) and then bonding the endcapped polyimide (PI) to silicalite‐1. The APTES‐endcapped polyimide precursors reacted with silanol groups on the silicalite‐1 surface and were transformed into the final polyimide (PI) matrices. Five precursors were used to create five series of MMMs; each series contained membranes with a content of silicalite‐1 ranging from 0 to 50 wt %. The helium permeability coefficient of the membranes was measured and found to be dependent on both the amount of filler and type of PI matrix. In the most permeable series, helium permeability coefficient increased from 16.3 × 10−15 mol m−1 s−1 Pa−1 for unfilled membranes to 69.1 × 10−15 mol m−1 s−1 Pa−1 for membranes containing 30 wt % silicalite‐1. The ideal helium/nitrogen separation factor ranged between 22 and 45. Thus, it seems that our novel approach improves the interfacial adhesion of MMMs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Preparation of Multiple Interaction Membrane Chromatography using Mixed Matrix Membrane Preparation Concept

Preparation of Multiple Interaction Membrane Chromatography using Mixed Matrix Membrane Preparation Concept

Synthesis of MEL type zeolite with different kinds of morphology for the recovery of 1-butanol from aqueous solution

Size, shape and morphology of zeolite crystallites play an important role in the synthesis of mixed matrix membranes having good membrane productivity, selectivity and stability. In the present work emphasis is placed on the use of hydrothermally synthesized high silica MEL type zeolite with hydrophobic character for the preparation of mixed matrix membranes. The morphological study shows that the sizes for crystals of MEL3 and MEL5 are at the nano scale while for hexagonal crystals of MEL4 and spherical crystals of MEL6 ranges in micro scale (20–35μm). The prime objective of this study is to develop new zeolite for the preparation of mixed matrix membrane, so before the use of these materials for the same purpose, adsorption potentials of these zeolite materials for 1-butanol were also investigated. Thereafter adsorption data was fitted to the Langmuir and Freundlich adsorption models. The later model achieved best fit with the experimental data. The high negative value of Gibbs free energy change (∆Go) indicates the feasible and spontaneous adsorption of 1-butanol on MEL6 zeolite. Negative values of heat of adsorption (∆Ho) and entropy change (∆So) indicate exothermic adsorption process with low degree of randomness.

CO2Transport in Polysulfone Membranes Containing Zeolitic Imidazolate Frameworks As Determined by Permeation and PFG NMR Techniques

This work describes the preparation of mixed matrix membranes by casting from poly(1,4-phenylene ether−ether−sulfone) chloroform solutions containing dispersed zeolitic imidazolate frameworks. Diffusive studies of CO2 in the pristine poly(1,4-phenylene ether−ether−sulfone) membrane and composite membranes were performed at 6 bar and 298 K, using pulsed field gradient NMR techniques. The evolution of the heterogeneity of the diffusion environments as seen by NMR was monitored in terms of the diffusion time and a stretching parameter. The values of the self-diffusion coefficient increase with filler content, from 2.1 × 10−8 cm2 s−1 for pristine membranes to 9.3 × 10−8 cm2 s−1 for membranes with 30 wt % of filler. Sorption and permeation experiments carried out at different pressures were used to determine the dual-mode model parameters that describe the transport processes. Apparent diffusion coefficients of CO2 in the membranes were obtained from the time lag method, from parameters of the dual-mode model,...