Search

Membrane separation is a high-efficiency, energy-saving, and environment-friendly separation technology. Covalent organic framework (COF)-based mixed-matrix membranes (MMMs) have broad application prospects in gas separation and are expected to provide new solutions for coal-bed methane purification. Herein, a high-throughput screening method is used to calculate and evaluate COF-based MMMs for CH4/N2 separation. General design rules are proposed from thermodynamic and kinetic points of view using the computation-ready, experimental COFs. From our database containing 471671 generated COFs, 5 COF membrane materials were screened with excellent membrane selectivities, which were then used as the filler of MMMs for separation performance evaluation. Among them, BAR-NAP-Benzene_CF3 combined with polydimethylsiloxane and styrene-b-butadiene-b-styrene show high CH4 permeability of 4.43×10–13 mol·m·s–1·Pa–1·m–2 and high CH4/N2 selectivity of 9.54, respectively. The obtained results may provide reasonable information for the design of COF-based membranes for the efficient separation of CH4/N2.

Adhesion between fillers and a polymeric matrix is an essential characteristic for mixed-matrix membranes for molecular separation to avoid defects and cavities that would decrease selectivity. We ...

Food packaging with efficient antibacterial ability is highly desirable and challenging in facing the crisis of microbial contamination. However, most present packaging is based on metal-based antibacterial agents and requires a time-consuming antibacterial process. Here, the unique packaging (CC/BB films) featuring aggregation-induced emission behavior and photodynamic inactivation activity is prepared by dispersing self-assembled berberine-baicalin nanoparticles (BB NPs) into a mixed matrix of sodium carboxymethylcellulose-carrageenan (CC). The superiority of this design is that this packaging film can utilize sunlight to generate reactive oxygen species, thus eradicating more than 99% of E. coli and S. aureus within 60 min. Also, this film can release BB NPs to inactivate bacteria under all weather conditions. Surprisingly, the CC/BB nanocomposite film presented excellent mechanical performances (29.80 MPa and 38.65%), hydrophobicity (117.8°), and thermostability. The nanocomposite film is validated to be biocompatible and effective in protecting chicken samples, so this work will provide novel insights to explore safe and efficient antibacterial food packaging.

Membrane-based technology is a low-cost alternative for gas purification processes due to its easy implementation and low energy consumption. However, the participation of membrane systems in the CO2 separation technologies market for natural gas sweetening is only 10% due to the trade-off between permeability and selectivity and poor stability of the polymeric materials available. Therefore, to expand current operating conditions or meet adverse requirement in new applications, such as low pressure and high flue gas temperatures, new membrane materials need to be developed. Mixed matrix membranes (MMMs) formed by the incorporation of inorganic fillers in polymeric matrices can overcome the high cost of inorganic membranes and reduce polymeric membrane limitations. The main challenge is the development of MMMs with a defect-free interfacial morphology. In this sense, the type of load is one of the most important factors. Among the inorganic fillers, carbon nanotubes (CNTs) have great potential for chemical adaptation, as well as high mechanical and thermal properties, which can result in high performance MMMs. This review was prepared to summarize the advances achieved with polymeric matrices incorporated with CNTs (CNTs-MMMs) and contribute to their development by showing the possibilities of combining CNTs with different polymers and their respective properties. It has been observed that CNTs can increase the mechanical, thermal and transport properties of polymeric membranes. Furthermore, Robeson's upper bound revealed that some CNTs-MMMs were suitable for industrial use because of their excellent performances and with greatest application potential for CO2/N2 separation.

Mixed matrix membranes (MMM's) comprising cellulose acetate (CA) polymers with nano-activated carbon (nAC) were prepared and derived from Oil Palm Empty Fruit Bunches (OP-EFB) biowaste. At first, nAC's were prepared using carbonization-activation process, with pyrolysis temperatures applied at 300, 400, and 500°C, respectively. Furthermore, 100 kg/m3 ZnCl2 solution were added for the activation process before sonicated at 28 kHz for 45 minutes. The adsorption performances were tested by using iodine value. The nAC prepared under carbonization temperature of 500°C, showed the best properties, i.e. 3.67% water content, 7.68% ash content, 22.87% volatile substances, 69.45% pure activated carbon levels and iodine value of 1000.35 mg/g, therefore selected and embedded into polymeric membrane matrices. In order to produce membranes matrix, cellulose was extracted from OP-EFB by 5-steps processes, i.e. preparation, hydrolysis, delignification, pulping and bleaching to obtaine α-cellulose. The extracted α-cellulose then activated, acetelized, hydrolyzed, sedimented and dryed to produce cellulose acetatate (CA) polymers. Then, the CA matrixes filled with different ratios of CA:nAC, i.e. (4:1), (4:3), (4:5), to prepare mixed matrix membranes. The MMM's were then tested to adsorp CO, CO_2 and hydrocarbons produced by motorcycle combustion process. The highest pollutant removal was 16.12% and 11.77%, for CO and CO_2, respectively, while the highest HC removal was 15.23%. The biowaste-based MMM's were proven to decrease motorcycle exhaust gases from the testing chamber, comply with SNI (Indonesian National Standard) and contributed to environmental recovery.

Abstract The most promising approaches to making polysiloxane-based membranes more selective are considered. These approaches can be subdivided into three groups: (1) development of new membrane materials by copolymerization, (2) modification of the polysiloxane chain (in the backbone and pendant chains), and (3) development of mixed matrix membranes. All the three approaches are subjected to a critical analysis, and conclusions are made on the prospects for the development of high-selectivity materials and high-performance membranes based on them. The data are presented from the viewpoint of applied aspects of polysiloxane-based membranes.

MCM-41 and SBA-15 mesoporous silica materials with different pore sizes (3.08 nm for small pore size MCM-41 (P 1), 5.89 nm for medium pore size SBA-15 (P 2), and 7.81 nm for large pore size SBA-15 (P 3)) were synthesized by the hydrothermal method and then functionalized with 3-aminopropyltrietoxysilane by postsynthesis treatments. Next, polysulfone-mesoporous silica mixed matrix membranes (MMMs) were prepared by the solution casting method. The obtained materials and MMMs were characterized by various techniques including X-ray diffraction, scanning electron microscopy, and N2 adsorption-desorption, and Brunauer-Emmett-Teller method to examine the crystallinity, morphology, and particle size, pore volume, specific surface area, and pore size distribution, respectively. Finally, the gas permeation rates of prepared MMMs were measured in 8 bar and 25 °C and the effect of pore size of modified and unmodified mesoporous silica on the gas separation performance of these MMMs were investigated. The experimental results indicate that the carbon dioxide (CO2) and methane (CH4) permeability and CO2/CH4 selectivity were increased with an enhancement in the particle pore size.

Polymeric gas separation membranes have become a competent technology over the past few decades. This review focuses on the broad classifications of membrane materials and the criteria for the selection of membrane materials, describes the various synthesis routes adopted for membrane fabrication, and explains various gas transport mechanisms. A comparison of membrane-based separation technology with other conventional technologies has also been made. The review also discusses the current polymers used for gas separations, current commercially viable membrane-based gas separation processes, and various limitations associated with the development of membrane material and separation processes. Further, various new classes of membranes developed for gas separations, including thermally rearranged polymers, polymers of intrinsic microporosity, room temperature ionic liquids, perfluoro polymers, and mixed matrix membranes, that has high separation performance has also been discussed. Some of the emerging membrane-based gas separations are also reviewed.

Cerium oxide (ceria) contains two stable states of cerium ions (Ce3+ and Ce4+). The presence of these two states and the ability to swap from one state to another (Ce3+ ↔ Ce4+) by scavenging the highly reactive oxygen species (ROS) generated from radiolysis of water, ensure the enhanced stability of polysulfone (Psf) membranes in the γ-radiation environment. In this study, the ROS scavenging ability of ceria was studied. Ceria nanoparticles were found to scavenge ROS like hydroxyl radicals and hydrogen peroxide (H2O2). The H2O2 scavenging is due to the peroxidase-like catalytic activity of ceria nanoparticles. The ROS scavenging is responsible for offering protection to the Psf host matrix and in turn the stability to the Psf-ceria mixed-matrix membranes (MMMs) in γ-radiation environment. Thus, presence of ceria nanoparticles provides an opportunity for utilizing Psf-ceria MMMs in ionizing radiation environment with increased life span, without compromise in the performance.

In our study, the synthesis of zeolitic imidazolate framework (ZIF-12) crystals and the preparation of mixed matrix membranes (MMMs) with various ZIF-12 loadings were targeted. The characterization of ZIF-12 and MMMs were carried out by Fourier transform infrared spectroscopy analysis, thermogravimetric analysis, scanning electron microscopy (SEM), and thermomechanical analysis. The performance of MMMs was measured by the ability of binary gas separation. Commercial polyetherimide (PEI-Ultem® 1000) polymer was used as the polymer matrix. The solution casting method was utilized to obtain dense MMMs. In the SEM images of ZIF-12 particles, the particles with a rhombic dodecahedron structure were identified. From SEM images, it was observed that the distribution of ZIF-12 particles in the MMMs was homogeneous and no agglomeration was present. Gas permeability experiments of MMMs were measured for H2, CO2, and CH4 gases at steady state, at 4 bar and 35 °C by constant volume-variable pressure method. PEI/ZIF-12-30 wt% MMM exhibited high permeability and ideal selectivity values for H2/CH4 and CO2/CH4 were P H 2 / CH 4 = 331.41 ${P}_{{\text{H}}_{2}/{\text{CH}}_{4}}=331.41$ and P CO 2 / CH 4 = 53.75 ${P}_{{\text{CO}}_{2}/{\text{CH}}_{4}}=53.75$ gas pair.

In order to realize the efficient industrial production of Ilex “China Girl”, an orthogonal experiment with 4 factors and 3 levels was designed. Firstly, the optimal orthogonal cutting scheme was selected from 9 treatments. Then through the systematic analysis of the effects of cutting position, substrate, exogenous hormones type and concentration on rooting indexes, such as rooting rate, root number, root length and root effect index, the theoretical optimal scheme was predicted and verified. The results showed that the theoretical optimal scheme (3000 mg/L IBA treatment for 15 s, cutting in mixed matrix with peat soil, perlite and vermiculite ratio of 2:1:1) was the optimal cutting rooting scheme of Ilex “China Girl”. After the treatment of this scheme, the rooting rate of Ilex “China Girl” reached 100%, the average root number was 51.67 per plant, and the average root length was 6.13 cm. The rooting time was greatly shortened, the rooting rate and rooting effect were greatly improved. In this study, the efficient cutting propagation technology system of Ilex “China Girl” was established, which laid a foundation for the popularization and application of Ilex “China Girl”, and also provided reference for further improving the cutting propagation efficiency of other evergreen holly. This study laid a foundation for the application of Ilex “China Girl”, and also provided a reference for further improving the cutting propagation efficiency of other evergreen holly.

To enhance the performance of the polyphenylene sulfone (PPSU) membrane, a novel mixed matrix membrane with hydrophilicity and antifouling properties was prepared. Using PPSU as the basic membrane material, polyvinyl pyrrolidone (PVP) as the porogen, N-Methyl pyrrolidone (NMP) as the solvent, and MOF-CAU-1 (Al4(OH)2(OCH3)4(H2N-BDC)3·xH2O) as the filler, PPSU/CAU-1 mixed matrix membrane (MMM) was prepared by an immersion precipitation and phase transformation technique. By changing the amount of MOF-CAU-1, the properties and performance of the MMM membrane were investigated in terms of hydrophilicity, pore morphology, surface roughness, and dye removal. The results show that the highest pure water flux of the mixed reached 47.9 L·m−2·h−1, when the CAU-1 addition amount was 1.0 wt%, which was 23% higher than that of the pure PPSU membrane. Both the rejection rate and the antifouling performance of the MMM membrane also noticeably improved.

A periodic mesoporous organosilica (PMO) Janus nanoparticle (PMO-SO3H&SiO2-NR) was gently synthesized and mixed with polyethersulfone (PES) to fabricate a series of mixed matrix membranes via the phase inversion method. The Janus structure of PMO-SO3H&SiO2-NR nanoparticle enabled the hydrophilic –SO3H and hydrophobic hexadecyl (-NR) to be separately distributed on the PMO cores and SiO2 branches, and hence Janus PMO-SO3H&SiO2-NR nanoparticle was endowed with good hydrophilicity and excellent compatibility with PES membrane matrix. As a result, the mixed matrix membranes presented improved bulk porosity, surface mean pore size, hydrophilicity and permeability. Particularly, the pure water flux of the mixed matrix membrane with 5 wt% porous Janus PMO-SO3H&SiO2-NR nanoparticles (M5) was as high as 330 l・m–2・h–1 that was 2.2 times that of the pristine PES ultrafiltration (UF) membrane (M0) while its rejection for bovine serum albumin (BSA) remained above 98.0%. Besides, after multi-cycles UF experiment with BSA as model contaminant, M5 retained a high flux recovery rate, permeation flux and rejection, suggesting its outstanding overall performance. Porous Janus PMO-SO3H&SiO2-NR nanoparticle is the first time to be used as an effective additive to prepare mixed matrix membrane, providing a new approach to achieve highly efficient water treatment of UF membranes.

Tremendous progress in two-dimensional (2D) nanomaterial chemistry affords abundant opportunities for the sustainable development of membranes and membrane processes. In this review, we propose the concept of mixed dimensional membranes (MDMs), which are fabricated through the integration of 2D materials with nanomaterials of different dimensionality and chemistry. Complementing mixed matrix membranes or hybrid membranes, MDMs stimulate different conceptual thinking about designing advanced membranes from the angle of the dimensions of the building blocks as well as the final structures, including the nanochannels and the bulk structures. In this review, we survey MDMs (denoted nD/2D, where n is 0, 1 or 3) in terms of the dimensions of membrane-forming nanomaterials, as well as their fabrication methods. Subsequently, we highlight three kinds of nanochannels, which are 1D nanochannels within 1D/2D membranes, 2D nanochannels within 0D/2D membranes, and 3D nanochannels within 3D/2D membranes. Strategies to tune the physical and chemical microenvironments of the nanochannels as well as the bulk structures based on the size, type, structure and chemical character of nanomaterials are discussed. Some representative applications of MDMs are illustrated for gas molecular separations, liquid molecular separations, ionic separations and oil/water separation. Finally, current challenges and a future perspective on MDMs are presented.

The excessive use of natural gas and other fossil fuels by the industrial sector leads to the production of great quantities of gas pollutants, including CO2, SO2, and NO x . Consequently, these gases increase the temperature of the earth, producing global warming. Different strategies have been developed to help overcome this problem, including the utilization of separation membrane technology. Mixed matrix membranes (MMMs) are hybrid membranes that combine an organic polymer as a matrix and an inorganic compound as a filler. In this study, MMMs were prepared based on polyethersulfone (PES) and a type of metal–organic framework (MOF), Materials of Institute Lavoisier (MIL)-100(Al) [Al3O(H2O)2(OH)(BTC)2] (BTC: benzene 1,3,5-tricarboxylate) using a phase inversion method. The influence on the properties of the produced membranes by addition of 5, 10, 20, and 30% MIL-100(Al) (w/w) to the PES was also investigated. Fourier-transform infrared spectroscopy (FTIR) analysis indicated that no chemical interactions occurred between PES and MIL-100(Al). Scanning electron microscope (SEM) images showed agglomeration at PES/MIL-100(Al) 30% (w/w) and that the thickness of the dense layer increased up to 3.70 µm. After the addition of MIL-100(Al) of 30% (w/w), the permeability of the MMMs for CO2, O2, and N2 gases was enhanced by approximately 16, 26, and 14 times, respectively, as compared with a neat PES membrane. The addition of MIL-100(Al) to PES increased the thermal stability of the membranes, reaching 40°C as indicated by thermogravimetry analysis (TGA). An addition of 20% MIL-100(Al) (w/w) increased membrane selectivity for CO2/O2 from 2.67 to 4.49 (approximately 68.5%), and the addition of 10% MIL-100(Al) increased membrane selectivity for CO2/N2 from 1.01 to 2.12 (approximately 110.1%).

Ionic liquids (ILs) have become attractive in membranes for CO₂ separation because of the designable structure, high CO₂ affinity, and good compatibility and stability. Modification of metal–organic frameworks with ILs is an effective strategy to improve the gas separation performance of mixed matrix membranes (MMMs). In this work, task-specific ionic liquids (TSILs) were incorporated to prepare TSIL@ZIF-67/PIM-1 MMMs and improve CO₂ separation performance because of the high CO₂ solubility and great compatibility toward ZIF-67 and PIM-1. The TSILs (TMGHIM and TMGHPhO) selectively and reversibly interact with CO₂ and improve the interfacial compatibility between ZIF-67 and PIM-1, leading to higher CO₂/CH₄ and CO₂/N₂ selectivities than that of the ZIF-67/PIM-1 MMM and the directly blended membrane (TSIL/ZIF-67/PIM-1). The 10 wt % TMGHIM@ZIF-67/PIM-1 MMM shows enhanced CO₂/N₂ and CO₂/CH₄ selectivities of 13.7 and 10.5, respectively; meanwhile, the CO₂ permeability reaches 12,848.5 Barrer and is 2.5 times that of the pure PIM-1 membrane. The TSIL@ZIF-67/PIM-1 MMMs also show good stability against physical aging.

Metal–organic framework (MOF)-based mixed matrix membranes have become a research hotspot in separation field owing to the compatibility between MOF particles and the polymeric matrix. Herein, thre...

Mixed matrix membranes (MMMs) with cloisite® 15A clay in polyimide (PI) matrix were matured for gas separation applications. The inorganic cations of clay were replaced with cloisite® 15A as modifi...

A facile strategy to elevate gas separation performances of polymers is to introduce a versatile particle. In this study, the novel F-Ce nanosheets are synthesized, and then F-Ce is functionalized ...

Separation technology by using membranes is an effective choice for water treatment, but fouling is a significant problem for membrane applications. Recently, transition-metal dichalcogenide nanosh...

Mixed-matrix membranes (MMMs) have received considerable interest because of their capability to synergize polymeric and nanomaterials. Extensive experimental and a handful of simulation studies on...

Covalent organic frameworks (COFs) are increasingly utilized as doping agents for the design of advanced ultrafiltration mixed matrix membranes, thanks to their prominent nanoporosity and excellent...

Polyvinylidene fluoride (PVDF) membranes, enhanced with metal-organic framework (MOF), were fabricated on a non-woven polyethylene terephthalate (PET) support using the non-solvent induced phase inversion (NIPS) method to produce mixed matrix membrane (MMM). Polymer concentration of 10%, 15%, and 20% were used in the study whereas UiO-66(Zr) was used as a MOF filler. The resulting membranes were characterized in terms of their morphology, porosity, wettability, mechanical strength, pure water flux, and gas permeability. Results show that the presence of UiO-66(Zr) filler improved membrane morphology, mechanical strength, and hydrophobicity of MMM as compared to pristine PVDF.

The interfacial design is critical in preparing high-performance mixed matrix membranes (MMMs), especially for the separation of larger sized components from mixtures. Herein, a facile and novel st...

Fine-tuning and pore environment control of covalently connected metal-organic framework (MOF) and mixed-matrix membrane (MMM) composite materials were achieved. Core-shell-type, dual-functionalize...

Membrane technology without a phase-change process has demonstrated its low-cost, high-energy-efficiency advantages. High fractional free volume polymers of intrinsic microporosity (PIMs), such as ...

Mixed matrix membrane (MMM), a developing research area, is a membrane formed by incorporating fillers in the polymeric membrane to enhance gas separation performance. In this study, MMMs comprised of blend rubbery block copolymers of polyether block amide (Pebax-1657) with a glassy polyethersulfone (PES) polymer and multi-walled carbon nanotubes (MWCNTs) were synthesized by dry phase inversion method and explored further by gas permeability test. Pebax-1657/PES/MWCNTs membrane resulted in an increased permeability as well as CO2/CH4 selectivity. The Pebax-1657/PES polymer blend MMM with 10wt% of MWCNTs has shown the most superior performance of CO2 permeability, CH4 permeability and CO2/CH4 selectivity in comparison with the pure Pebax-1657 resulted in 66.3% and 11.6% difference respectively.