Flat Sheet Mixed Matrix Membranes Research Articles

Nanocarbon-Based Mixed Matrix Pebax-1657 Flat Sheet Membranes for CO2/CH4 Separation.

In the present work, Pebax-1657, a commercial multiblock copolymer (poly(ether-block-amide)), consisting of 40% rigid amide (PA6) groups and 60% flexible ether (PEO) linkages, was selected as the base polymer for preparing dense flat sheet mixed matrix membranes (MMMs) using the solution casting method. Carbon nanofillers, specifically, raw and treated (plasma and oxidized) multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) were incorporated into the polymeric matrix in order to improve the gas-separation performance and polymer's structural properties. The developed membranes were characterized by means of SEM and FTIR, and their mechanical properties were also evaluated. Well-established models were employed in order to compare the experimental data with theoretical calculations concerning the tensile properties of MMMs. Most remarkably, the tensile strength of the mixed matrix membrane with oxidized GNPs was enhanced by 55.3% compared to the pure polymeric membrane, and its tensile modulus increased 3.2 times compared to the neat one. In addition, the effect of nanofiller type, structure and amount to real binary CO2/CH4 (10/90 vol.%) mixture separation performance was evaluated under elevated pressure conditions. A maximum CO2/CH4 separation factor of 21.9 was reached with CO2 permeability of 384 Barrer. Overall, MMMs exhibited enhanced gas permeabilities (up to fivefold values) without sacrificing gas selectivity compared to the corresponding pure polymeric membrane.

Thin Film Mixed Matrix Hollow Fiber Membrane Fabricated by Incorporation of Amine Functionalized Metal-Organic Framework for CO2/N2 Separation.

Membrane separation technology can used to capture carbon dioxide from flue gas. However, plenty of research has been focused on the flat sheet mixed matrix membrane rather than the mixed matrix thin film hollow fiber membranes. In this work, mixed matrix thin film hollow fiber membranes were fabricated by incorporating amine functionalized UiO-66 nanoparticles into the Pebax® 2533 thin selective layer on the polypropylene (PP) hollow fiber supports via dip-coating process. The attenuated total reflection-Fourier transform infrared (ATR-FTIR), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) mapping analysis, and thermal analysis (TGA-DTA) were used to characterize the synthesized UiO-66-NH2 nanoparticles. The morphology, surface chemistry, and the gas separation performance of the fabricated Pebax® 2533-UiO-66-NH2/PP mixed matrix thin film hollow fiber membranes were characterized by using SEM, ATR-FTIR, and gas permeance measurements, respectively. It was found that the surface morphology of the prepared membranes was influenced by the incorporation of UiO-66 nanoparticles. The CO2 permeance increased along with an increase of UiO-66 nanoparticles content in the prepared membranes, while the CO2/N2 ideal gas selectively firstly increased then decreased due to the aggregation of UiO-66 nanoparticles. The Pebax® 2533-UiO-66-NH2/PP mixed matrix thin film hollow fiber membranes containing 10 wt% UiO-66 nanoparticles exhibited the CO2 permeance of 26 GPU and CO2/N2 selectivity of 37.

Polyethersulfone ultrafiltration membrane incorporated with ferric-based metal-organic framework for textile wastewater treatment

• Incorporation of Fe-MOF nanoparticles improved dye rejection of polymeric membrane. • The optimum loading of Fe-MOF for the MMM fabrication is 6 wt%. • The developed MMM is promising for the treatment of textile wastewater. The wastewater discharged from dye-manufacturing industries can pose severe problems to the ecosystem and the use of conventional ultrafiltration (UF) polymeric membrane is still not capable of removing dyes from the wastewater. In this work, hybrid flat sheet mixed matrix membranes were fabricated by blending polyethersulfone (PES) with different weight percentage of ferric-based metal–organic framework (Fe-MOF), aiming to overcome the drawback of PES membrane. Findings revealed that the Fe-MOF/PES membranes attained excellent rejections (>98.5%) for cationic and anionic dyes with its optimum permeation flux as high as 165.68 L/m 2 h, comparable to other reported UF membranes. Moreover, the fouling study conducted using real textile wastewater revealed the potential of the hybrid membrane for reducing the levels of total suspended solid (100% rejection) and chemical oxygen demand (>92%) while exhibiting high flux recovery rate (>90%). These results suggested that the Fe-MOF/PES hybrid UF membrane has great potential for efficient industrial wastewater treatment.

A high-flux P84 polyimide mixed matrix membranes incorporated with cadmium-based metal organic frameworks for enhanced simultaneous dyes removal: Response surface methodology

The water sources contaminated by toxic dyes would pose a serious problem for public health. In view of this, the development of a simple yet effective method for removing dyes from industrial effluent has attracted interest from researchers. In the present work, flat sheet mixed matrix membranes (MMMs) with different physiochemical properties were fabricated by blending P84 polyimide with different concentrations of cadmium-based metal organic frameworks (MOF-2(Cd)). The resultant membranes were then used for simultaneous removal of eosin y (EY), sunset yellow (SY) and methylene blue (MB) under various process conditions. The findings indicated that the membranes could achieve high water permeability (117.8–171.4 L/m2.h.bar) and promising rejection for simultaneous dyes removal, recording value of 99.9%, 81.2% and 68.4% for MB, EY and SY, respectively. When 0.2 wt% MOF-2(Cd) was incorporated into the membrane matrix, the membrane separation efficiency was improved by 110.2% and 213.3% for EY and SY removal, respectively when compared with the pristine membrane. In addition, the optimization and modeling of membrane permeate flux and dye rejection was explored using response surface methodology. The actual and model results are in good agreement with R2 of at least 0.9983 for dye rejection and permeate flux. The high flux of the developed MMMs coupled with effective separation of dyes suggests a promising prospect of using P84 polyimide MMMs incorporated with MOF-2(Cd) for water purification.

Dynamic modelling and experimental validation of CO2 removal using hydrophobic membrane contactor with different types of absorbent

In this study, a dynamic model was proposed to simulate and validate the profile of carbon dioxide (CO2) absorption using in-house fabricated mixed matrix membrane (MMM) from membrane gas absorption (MGA) contactors. The flat sheet MMM was fabricated by incorporating TS-530 fumed silica nanoparticles into polyvinylidene fluoride (PVDF) polymer matrix. The membrane surface was coated with low-density polyethylene (LDPE) to enhance membrane hydrophobicity and performance. The performance of the membrane on CO2 absorption was tested in the MGA contactor using different types of liquid absorbent; water, 2-amino-2-methyl-1-propanol (AMP) and dimethylamine (DEA). The mass transfer of CO2 through gas phase, membrane and liquid phase was taken into account in the proposed model. The physical and chemical absorption in liquid phase was also considered during the simulation process. Other than Henry’s constant of CO2 into the absorbent, the solubility of CO2 in the polymeric membrane was also found to have a significant effect on the CO2 absorption. The simulation results were found to be in agreement with the experimental data of CO2 absorption flux.

Development of Polysulfone/Activated Carbon Nanofibers Mixed Matrix Membrane for CO2/CH4 Separation

This study was performed primarily to investigate the effect of activated carbon nanofiber (ACNF) on carbon dioxide and methane separation performance of mixed matrix membrane (MMM). In this study, polysulfone (PSf)/ACNF mixed matrix membranes was fabricated using dry/wet inversion technique. The effect of PSf concentration and ACNF loading on the performance of mixed matrix membrane in terms of permeability and selectivity of CO2/CH4 gas separation was observed. The fabricated flat sheet mixed matrix membranes were characterized using Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analysis. From the SEM observations, it shows that sponge like structures images were observed upon the addition of ACNFs in the PSf/ACNF membranes was slowly decreased due to increasing weight percentage of ACNF. FT-IR result indicating the presence of carboxyl group in MMM at wavelength 1750 cm-1. Meanwhile, the MMMs were further tested to pure permeation test using pure CO2 and CH4 gas, the CO2 permeance improved and the selectivity of CO2/CH4 increased after the addition of ACNFs.

Preliminary study on gas separation performance of flat sheet mixed matrix (PVDF/Zeolite)

Membrane separation has attracted a lot of attention over the last years mainly due to its separation ability, operational capability and economical viability. Mixed matrix membrane (MMM) combines the superior transport and selectivity properties of inorganic membrane materials and the excellent fabrication properties of organic polymers. This emerging technology can be utilized to purify biogas which can be used in a variety of applications. In this study, flat sheet mixed matrix membranes were synthesized with different percentages of N-Mehtyl-2-pyrrolidone (NMP) as solvent, Polyvinylidene Fluoride (PVDF) as the polymer matrix and zeolite 4A as the dispersed fine particles, membrane A (80: 20: 0), membrane B (80: 18: 2), membrane C (80: 15: 5), and membrane D (75: 15: 10) respectively. The membranes were fabricated using dry/wet phase inversion method. The membrane’s performance in terms of permeability and selectivity was examined using the single gas permeation device. The general trend was that, the permeability of the two gases (CO2/CH4) decreased with the increase of the pressure (0.5, 1, 1.5) bar. Membrane D was found to be suitable to separate the pair gas (CO2/CH4) as the permeability was 65623.412, Barrer and 15587.508, Barrer respectively, and its selectivity for was 4.21 at 0.5 bar.

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.

Preparation, characterization and humic acid removal capacity of chitosan coated iron-oxide- polyacrylonitrile mixed matrix membrane

Flat sheet mixed-matrix membranes (MMM) were cast using amine stabilized iron oxide nanoparticles (Fe3O4) and polyacrylonitrile (PAN) coated with chitosan. The effects of iron oxide impregnation (Fe3O4) and chitosan coating on removal of humic acid were investigated. The cast membranes were characterized by scanning electron microscopy (SEM), permeability, molecular weight cut off (MWCO), pore size, hydrophilicity, mechanical strength, Fourier transform infrared spectroscopy (FTIR), zeta potential, surface area and surface roughness. Mechanical strength and zeta potential of MMM increased (more positively charged) with Fe3O4 concentration. SEM images confirmed that MMM became denser with Fe3O4 impregnation. Adsorption of humic acid on MMM was quantified and Langmuir isotherm was fitted. The adsorption of HA by MMM was also confirmed by FTIR. The long term stability of MMM was investigated in a cross flow filtration unit. Effects of various operating conditions like transmembrane pressure, cross flow rate and feed concentration on membrane performance were also investigated. Atomic force microscopy (AFM) showed that, surface roughness of membrane was reduced with nanoparticles impregnation. Flux recovery ratio (FRR) also confirmed the antifouling nature of MMM.

Fabrication and evaluation of nanocomposite membranes of polyethersulfone/α-alumina for hydrogen separation

In this study, polyethersulfone (PES)-based nanocomposite membranes with the incorporation of inorganic filler of α-alumina were prepared via thermal phase inversion method. The fabricated flat sheet-mixed matrix membranes were characterized using X-ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and atomic force microscope analysis, and the permeation tests were performed for hydrogen, nitrogen and carbon dioxide. Also prepared α-alumina particles were identified by X-ray diffraction and the surface area, total pore volume and average pore diameter of particles were measured with a high-speed gas-sorption analyzer. The distribution and dispersion of α-alumina particles suspended in the polymer matrix were uniform and the surface roughness of the nanocomposite membranes was obviously lower than that of the pure membranes. The thermal analysis indicated that the glass transition temperature of the mixed matrix membranes was around 221.23 °C and the initial degradation temperature was up to 433 °C in air. The nanocomposite membranes increased the permeability of hydrogen, nitrogen and carbon dioxide gases and the hydrogen over nitrogen selectivity, simultaneously and shifted above the Robeson’s upper bound line-2008. The results showed that the nanocomposite membrane containing 8 wt % of α-alumina led to a considerable and simultaneous increase in the permeability of hydrogen (up to 8 times at pressure of 4 bar) and the selectivity of hydrogen over nitrogen (up to 2.4 times at pressure of 4 bar) in comparison to the neat polyethersulfone membranes. The pressure dependence of the gas permeability of the membranes was also investigated and based on selectivity versus permeability charts, the appropriate morphology of the nanocomposite membrane was suggested. Overall, the capability of α-alumina as an inorganic filler for hydrogen separation application has been shown.

Reduction of microbial contamination from drinking water using an iron oxide nanoparticle-impregnated ultrafiltration mixed matrix membrane: preparation, characterization and antimicrobial properties

Iron oxide nanoparticles were prepared and mixed in polyacrylonitrile to produce an ultrafiltration flat sheet mixed matrix membrane with high flux and adequate antimicrobial properties.

Hydrophilicity Effect of Rice Husk Silica on Mixed Matrix PSF Membrane Properties

The effects of two types of additives rice husk silica (RHS) towards membrane hydrophilicity and flux performance were investigated. Different percentages or concentrations of rice husk silica (RHS) additive were used to form a mixed matrix membrane. This flat sheet mixed matrix membrane was prepared via phase inversion technique. The fabricated membrane was characterized by contact angle and surface roughness measurements, whereas the flux permeation was measured using pure water flux. The result demonstrated that the addition both types of rice husk silica have increased the hydrophilicity properties of the mixed matrix membrane. Stronger effect of hydrophilicity is shown upon addition of amorphous rice husk particle where both contact angle and surface roughness were reduced and increased, respectively.

Effects of Aluminosilicate Mineral Nano-Clay Fillers on Polysulfone Mixed Matrix Membrane for Carbon Dioxide Removal

Over the last few decades, significant improvements in the performance of polymeric membranes for gas separation have been made. Nevertheless, the existing membrane materials need to be enhanced in order to fully exploit their gas separation application opportunities on industrial scale. Mixed matrix membrane which combines the advantages of the highly selective fillers and desirable properties of the polymer matrix is explored to overcome the trade-off trend between gas permeability and selectivity. This paper describes the effect of aluminosilicate mineral nano-clay fillers on polysulfone (PSF) mixed matrix membrane. In this study, different types of montmorillonite (MMT) nano-clays were used as fillers to fabricate asymmetric flat sheet mixed matrix membrane (MMM) via dry-wet phase inversion method. The interaction between the type of organoclay and its loading is also studied. The synthesis of MMM required N-methyl-2-pyrrolidone (NMP) as solvent and deionized water as coagulant. The fabricated MMMs were characterized by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and field emission scanning electron microsropy (FESEM). Thin asymmetric membrane with dense skin layer and porous sub-structure was successfully fabricated. Results showed enhancement in MMM stability relative to neat PSF membrane. It is also found that higher nano-clay loading resulted in significant agglomeration, nevertheless, there appears to be improved adhesion between the polymer and nano-clay.

Development of dual layer of ZIF-8/PEBAX-2533 mixed matrix membrane for CO2 capture

A new kind of self-supported dual layer mixed matrix membrane was developed in this work using ZIF-8 as inorganic filler in PEBAX-2533 polymer matrix. The developed dual layer flat sheet mixed matrix membrane was characterized to investigate the morphology of organic-based and inorganic-based layer. The gas separation properties of the mixed matrix membranes were tested using single gases CO2, CH4, N2, and O2 and a mixture of CO2 and N2 in dry and humidified conditions. The permeability of all examined gases increased as the inorganic filler content increased in the matrix membranes, and specifically it increased dramatically for CO2 in all cases, single feed gas and dry and humidified mixed gas. The CO2/N2 selectivity decreased slightly from 33.8 for the pure PEBAX membrane to 32.3 for the mixed matrix membrane with 35% ZIF-8 loading, while more significant drop in CO2/N2 selectivity was observed in experiments using mixed gases.

Adsorptive removal of fluoride by activated alumina doped cellulose acetate phthalate (CAP) mixed matrix membrane

Flat sheet mixed matrix membranes were prepared using cellulose acetate phthalate (CAP) and activated granular alumina using phase inversion technique. The membranes were characterized using porosity, permeability, molecular weight cut off (MWCO) and contact angle. Compositional analysis of the membrane was carried out by X-ray diffraction and the morphology and surface roughness were investigated by scanning electron microscope and atomic force microscope, respectively. The permeability of the membrane was reduced from 3.0×10−11 to 1.4×10−11m/Pas as alumina concentration increased from 0 to 35wt% for constant CAP concentration at 20wt%. Decrease in porosity from 75% to 45% supported the above fact. Membrane hydrophilicity was improved and most importantly, fluoride rejection from contaminated water increased to 91% using 35wt% of alumina. Maximum adsorption capacity for fluoride was 2.3mg/g for the mixed matrix membrane at room temperature. Continuous cross flow experiments revealed that the virgin membrane (24kDa), having a surface area of 0.01m2, could produce water well within the safety limit for a time of 11h. Regeneration study was conducted for five cycles. Effect of other co-existing anions on fluoride removal efficiency of the membrane was also studied.

Effects of montmorillonite nano-clay fillers on PEI mixed matrix membrane for CO 2 removal

This paper focuses on the effect of montmorillonite nano-clay fillers on polyetherimide (PEI) mixed matrix membrane, specifically upon the removal of carbon dioxide. Five different types of montmorillonite (MMT) nano-clays, including unmodified and industrially modified clays, were used as filler to fabricate asymmetric flat sheet mixed matrix membrane (MMM) via a dry/wet phase inversion technique. The five types of clay used were: raw MMT, Cloisite 15A, general MMT, hydrophobic MMT and hydrophilic MMT. The MMTs were characterized by X-ray diffractometry (XRD), thermal gravimetric analysis (TGA), Fourier-transform infrared (FTIR). The fabricated MMMs were characterized by differential scanning calorimetry (DSC), field emission scanning electron microscopic (FESEM) and pure gas permeation testing. The gas permeation results revealed the following order in terms of the permselectivity for CO 2/CH 4 separation: Cloisite 15A > general MMT > hydrophilic MMT > hydrophobic MMT > raw MMT. The best results were obtained at 0.5 wt.% Cloisite 15A loading where the selectivity enhancement was about 28% as compared to that of neat PEI.

Effect of Raw Multi-Wall Carbon Nanotubes on Morphology and Separation Properties of Polyimide Membranes

Raw multi wall carbon nanotubes (r-MWCNTs) were embedded as fillers inside the polyimide (PI) matrix and PI/r-MWCNTs mixed matrix membranes were fabricated by the phase inversion method. The TEM images and permeation results using helium as test gas showed that r-MWCNTs were generally closed ended and acted as impermeable nano particles. Gas permeation tests using CO2 and CH4 showed that the addition of r-MWCNTs into the dope solution increased the CO2/CH4 separation factor while decreasing the carbon dioxide and methane permeances. When the r-MWCNTs content was increased from 0% to 6 wt.%, permeance of CO2 in the flat sheet mixed matrix membranes decreased from 9.15 GPU to 5.49 GPU and CO2/CH4 separation factor increased from 19.05 to 45.75. Identical to flat sheet mixed matrix membranes, the addition of 2 wt.% r-MWCNTs into a spinning dope increased the CO2/CH4 separation factor from 46.61 to 72.20. The glass transition temperature of the mixed matrix flat sheet membranes increased with an increase in the r-MWCNTs content. This implies a good segmental-level attachment between the two phases that forms a rigidified polymer region at the polymer/r–MWCNTs interface. FESEM images showed well dispersed r-MWCNTs in the polymer matrix at a loading of 2 wt% r-MWCNTs.

Application of Activated Carbon Mixed Matrix Membrane for Oxygen Purification

This study is performed primarily to investigate the effect of activated carbon on oxygen separation performance of polyethersulfone mixed matrix membrane. In this study, polyethersulfone (PES)-activated carbon (AC) mixed matrix membranes were fabricated using dry/wet technique. This study investigates the effect of polyethersulfone concentration and activated carbon loading on the performance of mixed matrix membrane in terms of permeability and selectivity of O2/N2 gas separation. The fabricated flat sheet mixed matrix membranes were characterized using permeation test, Field Emission Scanning Electron Microscopy (FESEM) analysis and Differential Scanning Calorimetry (DSC). It was found that the activated carbon loading affected the gas separation performance of mixed matrix membrane. PES- 1wt% AC membrane yielded 3.75 of O 2 /N 2 selectivity, however 5 wt% of AC can produced 5 O 2 /N 2 selectivity