Process intensification of synthesis of metal organic framework particles assisted by ultrasound irradiation.

This study synthesized UiO-66, a typical Zr-Metal Organic Framework (MOF), by using an ultrasound-assisted synthesis method to reduce the synthesis time. This method was short-time ultrasound irradiation at the initial stage of the reaction. As compared with average particle size of conventional solvothermal method (=192 nm), averaged particle size by the ultrasound-assisted synthesis method showed particle sizes that were smaller on average, ranging from 56 to 155 nm. In order to compare the relative reaction rates of the solvothermal method and the ultrasound-assisted synthesis method, the cloudiness of the reaction solution in the reactor was observed with a video camera, and the luminance was calculated from the images obtained by the video camera. It was found that the ultrasound-assisted synthesis method showed a faster increase in luminance and shorter induction time than the solvothermal method. The slope of the luminance increase during the transient period was also found to become increase with the addition of ultrasound, which also affects the growth of particles. Observation of the aliquoted reaction solution confirmed that particle growth was faster in the ultrasound-assisted synthesis method than in the solvothermal method. Numerical simulations were also performed using MATLAB ver. 5.5 to analyze the unique reaction field generated by ultrasound. Bubble radius and temperature inside a cavitation bubble was obtained using the Keller-Miksis equation, which reproduces the motion of a single bubble. The bubble radius expanded and contracted repeatedly according to the ultrasound sound pressure, and eventually collapsed. The temperature at the time of collapse was extremely high, exceeding 17,000 K. It was confirmed that the high-temperature reaction field generated by ultrasound irradiation promoted nucleation, leading to a reduction in particle size and induction time.

Vapor-Induced Pore-Forming Atmospheric-Plasma-Sprayed Zinc-, Strontium-, and Magnesium-Doped Hydroxyapatite Coatings on Titanium Implants Enhance New Bone Formation-An In Vivo and In Vitro Investigation.

OBJECTIVES: Titanium implants are regarded as a promising treatment modality for replacing missing teeth. Osteointegration and antibacterial properties are both desirable characteristics for titanium dental implants. The aim of this study was to create zinc (Zn)-, strontium (Sr)-, and magnesium (Mg)-multidoped hydroxyapatite (HAp) porous coatings, including HAp, Zn-doped HAp, and Zn-Sr-Mg-doped HAp, on titanium discs and implants using the vapor-induced pore-forming atmospheric plasma spraying (VIPF-APS) technique. METHODS: The mRNA and protein levels of osteogenesis-associated genes such as collagen type I alpha 1 chain (COL1A1), decorin (DCN), osteoprotegerin (TNFRSF11B), and osteopontin (SPP1) were examined in human embryonic palatal mesenchymal cells. The antibacterial effects against periodontal bacteria, including Porphyromonas gingivalis and Prevotella nigrescens, were investigated. In addition, a rat animal model was used to evaluate new bone formation via histologic examination and micro-computed tomography (CT). RESULTS: The ZnSrMg-HAp group was the most effective at inducing mRNA and protein expression of TNFRSF11B and SPP1 after 7 days of incubation, and TNFRSF11B and DCN after 11 days of incubation. In addition, both the ZnSrMg-HAp and Zn-HAp groups were effective against P. gingivalis and P. nigrescens. Furthermore, according to both in vitro studies and histologic findings, the ZnSrMg-HAp group exhibited the most prominent osteogenesis and concentrated bone growth along implant threads. SIGNIFICANCE: A porous ZnSrMg-HAp coating using VIPF-APS could serve as a novel technique for coating titanium implant surfaces and preventing further bacterial infection.

Plasmonic nanostructure-enhanced Raman scattering for detection of SARS-CoV-2 nucleocapsid protein and spike protein variants.

Epidemiological control and public health monitoring during the outbreaks of infectious viral diseases rely on the ability to detect viral pathogens. Here we demonstrate a rapid, sensitive, and selective nanotechnology-enhanced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection based on the surface-enhanced Raman scattering (SERS) responses from the plasma-engineered, variant-specific antibody-functionalized silver microplasma-engineered nanoassemblies (AgMEN) interacting with the SARS-CoV-2 spike (S) and nucleocapsid (N) proteins. The three-dimensional (3D) porous AgMEN with plasmonic-active nanostructures provide a high sensitivity to virus detection via the remarkable SERS signal collection. Moreover, the variant-specific antibody-functionalization on the SERS-active AgMEN enabled the high selectivity of the SARS-CoV-2 S variants, including wild-type, Alpha, Delta, and Omicron, under the simulated human saliva conditions. The exceptional ultrahigh sensitivity of our SERS biosensor was demonstrated via SARS-CoV-2 S and N proteins at the detection limit of 1 fg mL-1 and 0.1 pg mL-1, respectively. Our work demonstrates a versatile SERS-based detection platform can be applied for the ultrasensitive detection of virus variants, infectious diseases, and cancer biomarkers.

Evaluation of the Specific Energy Consumption of Sea Water Reverse Osmosis Integrated with Membrane Distillation and Pressure-Retarded Osmosis Processes with Theoretical Models.

In this study, theoretical models for specific energy consumption (SEC) were established for water recovery in different integrated processes, such as RO-PRO, RO-MD and RO-MD-PRO. Our models can evaluate SEC under different water recovery conditions and for various proportions of supplied waste heat. Simulation results showed that SEC in RO increases with the water recovery rate when the rate is greater than 30%. For the RO-PRO process, the SEC also increases with the water recovery rate when the rate is higher than 38%, but an opposite trend can be observed at lower water recovery rates. If sufficient waste heat is available as the heat source for MD, the integration of MD with the RO or RO-PRO process can significantly reduce SEC. If the total water recovery rate is 50% and MD accounts for 10% of the recovery when sufficient waste heat is available, the SEC values of RO, RO-PRO, RO-MD and RO-MD-PRO are found to be 2.28, 1.47, 1.75 and 0.67 kWh/m3, respectively. These critical analyses provide a road map for the future development of process integration for desalination.

Interfacial nanoarchitectonics for ZIF-8 membranes with enhanced gas separation.

Metal-organic framework (MOF) membranes are potentially useful in gas separation applications. Conventional methods of MOF membrane preparation require multiple steps and high-pressure conditions. In this study, a reliable one-step interfacial synthesis method under atmospheric pressure has been developed to prepare zeolitic imidazolate framework-8 (ZIF-8) membranes supported on porous α-Al2O3 disks. To obtain optimal ZIF-8 membranes, three reaction parameters were investigated, namely, reaction temperature, reaction time, and concentration of the organic linker (i.e., 2-methylimidazole). The growth of ZIF-8 membranes under various parameters was evaluated by field-emission scanning electron microscopy, and the optimal synthesis conditions were determined (i.e., 80 °C for 12 h in 50 mM of 2-methylimidazole). The as-synthesized ZIF-8 membranes were then applied to CO2/N2 gas separation, which exhibited a maximum separation factor of 5.49 and CO2 gas permeance of 0.47 × 10-7 mol·m-2·s-1·Pa-1.

Aminosilane-Functionalized Zeolite Y in Pebax Mixed Matrix Hollow Fiber Membranes for CO2/CH4 Separation.

Due to their interfacial defects between inorganic fillers and polymer matrices, research into mixed matrix membranes (MMMs) is challenging. In the application of CO2 separation, these defects can potentially jeopardize the performance of membranes. In this study, aminosilane functionalization is employed to improve the nano-sized zeolite Y (ZeY) particle dispersion and adhesion in polyether block amide (Pebax). The performance of CO2/CH4 separation of Pebax mixed matrix composite hollow fiber membranes, incorporated with ZeY and aminosilane-modified zeolite Y (Mo-ZeY), is investigated. The addition of the zeolite filler at a small loading at 5 wt.% has a positive impact on both gas permeability and separation factor. Due to the CO2-facilitated transport effect, the performance of MMMs is further improved by the amino-functional groups modified on the ZeY. When 5 wt.% of Mo-ZeY is incorporated, the gas permeability and CO2/CH4 separation factor of the Pebax membrane are enhanced by over 100% and 35%, respectively.

Synthesizing Various Organic Polyacid Compounds for Modifying Forward Osmosis Membranes to Enhance Separation Performance.

In order to overcome the challenges of low permeate flux (Jp) and the accompanying reverse solute flux (JS) during the forward osmosis (FO) membrane separation process, we synthesized four hybrid materials of polyacid-based organic compounds and incorporated them into the selective polyamide (PA) layer to make novel thin-film nanocomposite (TFN) FO membranes. The Jp and JS of each membrane were evaluated and used along with membrane selectivity (Jp/JS) as indicators of membrane separation performance. The fabricated and modified membranes were also characterized for ridge and valley surface morphologies with increasing hydrophilicity and finger-shaped parallel channels in the PSf substrate. Moreover, two highly hydrophilic nanoparticles of graphene oxide (GO) and titanium oxide (TiO2) were introduced with the hybrid materials for PA modification, which can further enhance the Jp of the TFN membranes. The highest Jp of the TFN membranes achieved 12.1 L/m2-h using 0.1% curcumin-acetoguanamine @ cerium polyacid (CATCP) and 0.0175% GO. The characteristic peaks of the hybrid materials were detected on the membrane surface using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, evidencing successful incorporation of the hybrid materials during membrane modification. Here, we present the novel TFN membranes using hybrid materials for separation applications. The reactions for synthesizing the hybrid materials and for incorporating them with PA layer are proposed.

Modifying thin-film composite forward osmosis membranes using various SiO2 nanoparticles for aquaculture wastewater recovery.

This paper describes the fabrication, modification, and evaluation of the performance of thin-film composite (TFC) forward osmosis (FO) membranes for lab-scale aquaculture wastewater recovery using various fumed silica (SiO2) nanoparticles. The active polyamide (PA) layers of these membranes were novelly modified using different types of pretreated SiO2 nanoparticles [virgin SiO2, dried SiO2, and 3-aminopropyltriethoxysilane (APTES)-modified SiO2] and concentrations (0.05, 0,1, 0,2, and 0.4 wt%) to improve the membrane hydrophilicity with minimum particle agglomeration. Results show that the APTES-SiO2 modified membrane had the highest water flux and selectivity, followed by the dried-SiO2 modified membrane. The APTES coupling agent notably reduced the SiO2 aggregation on the membrane surface and improved membrane hydrophilicity. Consequently, high permeate flux and an acceptable reverse solute flux were observed. The optimal SiO2 concentration for PA modification was 0.1 wt% for all the nanoparticle types. The virgin and APTES-SiO2 modified membranes were used for aquaculture wastewater recovery. The water recovery rate reached 47% in 84 h when using the APTES-SiO2 modified membrane, while it reached only 26% in 108 h when using the virgin membrane. With a suitable design of the filtration apparatus and choice of draw solution (DS), the prepared novel TFC-FO membrane containing APTES-modified SiO2 can be used for recycling aquaculture wastewater into the DS, which can then be reused for other purposes.

In Vitro Bioactivity and Antibacterial Activity of Strontium-, Magnesium-, and Zinc-Multidoped Hydroxyapatite Porous Coatings Applied via Atmospheric Plasma Spraying.

The beneficial effects of Sr- and Mg-doped hydroxyapatite (HAp) on osteoblast proliferation and bone regeneration have been investigated in the past, and the antibacterial ability of Zn ions is well known. However, HAp coatings doped with these three elements via thermal spraying have not yet been investigated. In this study, HAp powder was synthesized at different pH values (4, 6, 8, and 10) and calcined at different temperatures (200, 400, 600, 800, and 1000 °C) to obtain HAp with the highest purity. Subsequently, strontium-, magnesium-, and zinc-doped HAp powders were synthesized at the optimal pH value and calcination temperature. The HAp powder was then coated onto Ti disks using atmospheric plasma spraying (APS) or vapor-induced pore-forming atmospheric plasma spraying (VIPF-APS) techniques at different working currents (350, 400, and 450 A) and spraying distances (10 and 15 cm). X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy equipped with energy-dispersive spectroscopy were used for material characterization to determine the optimal parameters. With these optimal coating parameters, HAp, Zn-HAp, SrMg-HAp, and ZnSrMg-HAp powders were deposited onto the Ti disks using VIPF-APS and named HAp-Ti, Zn-HAp-Ti, SrMg-HAp-Ti, and ZnSrMg-HAp-Ti, respectively. The in vitro bioactivity of these four groups was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and alkaline phosphatase (ALPase) activity assay. Besides, the antibacterial activities against Prevotella nigrescens, Porphyromonas gingivalis, and Fusobacterium nucleatum were assessed. The results showed that the purity of HAp synthesized at pH 10 and 800 °C was 98.40%. A porous coating without cracks was obtained at a 10 cm spraying distance and 400 A working current using VIPF-APS. SrMg-HAp-Ti and ZnSrMg-HAp-Ti resulted in higher osteoblast proliferation and ALPase activity than the control. Moreover, both Zn-HAp-Ti and ZnSrMg-HAp-Ti exhibited antibacterial activity against the three bacteria. Therefore, ZnSrMg-HAp has potential as a coating for biomedical materials due to its ability to reduce bacterial infection and enhance osseointegration.

Organic Liquid Mixture Separation Using an Aliphatic Polyketone-Supported Polyamide Organic Solvent Reverse Osmosis (OSRO) Membrane.

Energy-efficient membrane technology has received tremendous attention for the separation of organic molecules; however, the separation of molecules of less than 100 Da has remained challenging. Herein, a membrane fabricated from interfacial polymerization on a polyketone support was used as an organic solvent reverse osmosis (OSRO) membrane for the separation of organic liquid mixtures. The chemically stable and highly cross-linked selective layer exhibited outstanding separation factors toward large nonpolar molecules from small polar ones with high fluxes. For example, separation factors of 8.4, 11.1, 14.9, and 38.0 were achieved toward toluene, pentane, hexane, and heptane (10 wt % in mixtures), respectively, from methanol solution at 3 MPa, with fluxes around 5 LMH. This membrane outperformed the currently available reverse osmosis membrane and organic solvent nanofiltration membranes in terms of stability and separation factor. This work promotes the development of OSRO separation of organic liquid mixtures without phase change.

Mesoporous Silica Thin Membrane with Tunable Pore Size for Ultrahigh Permeation and Precise Molecular Separation.

We report on our use of a thin-layered vertical mesoporous silica thin film (MSTF) with tunable pore size overlaid on an anodic aluminum oxide (AAO) membrane for advancing water purification. The features of ultrathin thickness (about 20 nm), a uniform vertical pore orientation, low tortuosity, high porosity, and a hydrophilic surface endow the MSTF membranes with ultrahigh water permeability compared with that of state-of-the-art membranes. The modified E-MSTF membrane with a small pore diameter of 2.1 ± 0.1 nm demonstrates superior nanofiltration performance for dye molecules with a cutoff of 520 Da and ultrahigh water permeability of 310 ± 8 L m-2 h-1 bar-1. Furthermore, the precise molecular sieving of dye/salt mixtures was realized with outstanding salt permeation (97.5% NaCl, 96.0% Na2SO4) and a high retention of dye (99.0%). The water permeance and selectivity of the modified E-MSTF membrane are higher than that of reported membranes with similar dye rejections. This work opens up new avenues for constructing tailor-made membranes with tunable pore size and remarkable separation performance.

Molecular Dynamics Simulation Study of Solid Vibration Permeation in Microporous Amorphous Silica Network Voids.

Microporous silica membranes have silica polymer network voids smaller than 3 Å where only small gas molecules such as helium (2.6 Å) and hydrogen (2.89 Å) can be transported. These silica membranes are highly expected to be available for H2 separation. In order to examine gas permeation mechanisms in the silica polymer network voids, factors such as membrane porous structures, gas diffusivity, and gas permeability were studied via membrane permeation molecular dynamics simulation. The thermal motions of silica membrane constituent atoms were examined according to classic harmonic oscillation potential using a suitable amorphous silica structure and non-equilibrium molecular dynamics (NEMD) simulations of gas permeation. The dynamic model successfully simulated the gas permeation characteristics in an amorphous silica membrane with a suitable Hooke's potential parameter. The introduction of the oscillative thermal motion of the membrane atoms enhanced gas diffusivity. Helium and hydrogen diffusivity and permeability were analyzed using gas translation (GT) and solid vibration (SV) models. The diffusion distance of gas molecules between adsorption sites was around 5.5-7 Å. The solid-type vibration frequencies of gas molecules in the site were on the order of 1013 and were reasonably smaller for heavier helium than for hydrogen. Both the GT and SV models could explain the temperature dependency of helium and hydrogen gas diffusivities, but the SV model provided a more realistic geometrical representation of the silica membrane. The SV model also successfully explained gas permeability in an actual silica membrane as well as the virtual amorphous silica membrane.

Monodisperse ordered indium-palladium nanoparticles: synthesis and role of indium for boosting superior electrocatalytic activity for ethanol oxidation reaction.

The slow kinetics of ethanol oxidation reaction (EOR) has limited its widespread use for fuel cells. Bimetallic catalysts with optimized surface compositions can considerably govern rate-determining steps through selectivity for CH3COOH formation or by facilitating the adsorption of OHadsvia the bifunctional effect of an alloy to increase the EOR's kinetic rates. Here, we reported monodisperse ordered In-Pd nanoparticles as new bimetallic high-performance catalysts for EOR. In-Pd nanoparticles, i.e., In3Pd2 and In3Pd5 were prepared using arrested precipitation in solution, and their composition, structures, phase and crystallinity were confirmed using a variety of analyses including TEM, XPS, EDS and XRD. In-Pd nanoparticles were loaded on carbon black (Vulcan XC-72) as electrocatalysts for EOR in alkaline media. In3Pd2 and In3Pd5 nanoparticles exhibited 5.8 times and 4.0 times higher mass activities than commercial Pd/C, which showed that the presence of indium greatly boosts electrocatalytic reactivity for EOR of Pd catalysts. This performance is the best among those of bimetallic nanoparticles reported to date. Such high performance of In-Pd nanoparticles may be attributed to the following two reasons. First, In-Pd nanoparticles exhibited excellent CO anti-poison ability, as confirmed by CO striping experiments. Second, as revealed by DFT calculations of metals with OHads adsorption, In atoms on In3Pd2 surface exhibited the lowest energy (-1.659 eV) for OHads adsorption as compared to other common oxophilic metals including Sn, SnPt, Ag, Ge, Co, Pb, and Cu. We propose that the presence of indium sites promoted efficient free OH radical adsorption on indium sites and resulted in a faster reaction rate of acetate formation from acetaldehyde (the rate determining step for EOR on Pd sites). Finally, a single direct ethanol fuel cell (DEFC) with Pd/C anode was prepared. Compared to the results for a commercial Pd/C anode, the open circuit voltage (OCV) of In3Pd2/C improved by 0.25 V (from 0.64 to 0.89 V) and the power density improved by ∼80% (from 3.7 to 6.7 mW cm-2), demonstrating its practical uses as Pt or Pd catalyst alternatives for DEFC.

Effect of geometrical configuration of reactor on a ZrP nano-dispersion process using ultrasonic irradiation.

This study investigated the position of ultrasonic irradiation source and reactor geometry on fragmentation rate of a layered compound, α-zirconium phosphate (α-ZrP). By numerically solving the acoustic pressure distribution using COMSOL Multiphysics®, it is clarified the mechanism whereby the operating factors influenced the α-ZrP dispersion to make a suggestion of guideline of the process design method. Two vessels made of glass with a flat-bottom and a spherical-bottom, respectively, were used. Although the flat-bottom vessel at lower horn position showed the best performance of fragmentation, the region of high acoustic pressure field in the flat bottom vessel sharply narrowed and the transmittance became prominently low. On the other hand, no significant difference of the transmittance value in the spherical bottom vessel between the cases of low and high horn positions could be observed and the spherical bottom vessel was robust for the horn position. These results suggest that not only the magnitude of acoustic pressure but also the size of high acoustic pressure region is also an important factor and a spherical bottom vessel is one of suitable shape which gives large size of high acoustic pressure region regardless of the horn position.

Highly Zeolite-Loaded Polyvinyl Alcohol Composite Membranes for Alkaline Fuel-Cell Electrolytes.

Having a secure and stable energy supply is a top priority for the global community. Fuel-cell technology is recognized as a promising electrical energy generation system for the twenty-first century. Polyvinyl alcohol/zeolitic imidazolate framework-8 (PVA/ZIF-8) composite membranes were successfully prepared in this work from direct ZIF-8 suspension solution (0⁻45.4 wt %) and PVA mixing to prevent filler aggregation for direct methanol alkaline fuel cells (DMAFCs). The ZIF-8 fillers were chosen for the appropriate cavity size as a screening aid to allow water and suppress methanol transport. Increased ionic conductivities and suppressed methanol permeabilities were achieved for the PVA/40.5% ZIF-8 composites, compared to other samples. A high power density of 173.2 mW cm-2 was achieved using a KOH-doped PVA/40.5% ZIF-8 membrane in a DMAFC at 60 °C with 1⁻2 mg cm-2 catalyst loads. As the filler content was raised beyond 45.4 wt %, adverse effects resulted and the DMAFC performance (144.9 mW cm-2) was not improved further. Therefore, the optimal ZIF-8 content was approximately 40.5 wt % in the polymeric matrix. The specific power output was higher (58 mW mg-1) than most membranes reported in the literature (3⁻18 mW mg-1).

Strategies for Improving the Functionality of Zeolitic Imidazolate Frameworks: Tailoring Nanoarchitectures for Functional Applications.

Zeolitic imidazolate frameworks (ZIFs), a subclass of metal-organic frameworks (MOFs) built with tetrahedral metal ions and imidazolates, offer permanent porosity and high thermal and chemical stabilities. While ZIFs possess some attractive physical and chemical properties, it remains important to enhance their functionality for practical application. Here, an overview of the extensive strategies which have been developed to improve the functionality of ZIFs is provided, including linker modifications, functional hybridization of ZIFs via the encapsulation of guest species (such as metal and metal oxide nanoparticles and biomolecules) into ZIFs, and hybridization with polymeric matrices to form mixed matrix membranes for industrial gas and liquid separations. Furthermore, the developed strategies for achieving size and shape control of ZIF nanocrystals are considered, which are important for optimizing the textural characteristics as well as the functional performance of ZIFs and their derived materials/hybrids. Moreover, the recent trends of using ZIFs as templates for the derivation of nanoporous hybrid materials, including carbon/metal, carbon/oxide, carbon/sulfide, and carbon/phosphide hybrids, are discussed. Finally, some perspectives on the potential future research directions and applications for ZIFs and ZIF-derived materials are offered.

Nano-sized graphene flakes: insights from experimental synthesis and first principles calculations.

In this study, we proposed a cost-effective method for preparing graphene nano-flakes (GNFs) derived from carbon nanotubes (CNTs) via three steps (pressing, homogenization and sonication exfoliation processes). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), laser scattering, as well as ultraviolet-visible and photoluminescence (PL) measurements were carried out. The results indicated that the size of as-synthesized GNFs was approximately 40-50 nm. Furthermore, we also used first principles calculations to understand the transformation from CNTs to GNFs from the viewpoints of the edge formation energies of GNFs in different shapes and sizes. The corresponding photoluminescence measurements of GNFs were carried out in this work.

A Drying-Free, Water-Based Process for Fabricating Mixed-Matrix Membranes with Outstanding Pervaporation Performance.

Despite much progress in the development of mixed matrix membranes (MMMs) for many advanced applications, the synthesis of MMMs without particle agglomeration or phase separation at high nanofiller loadings is still challenging. In this work, we synthesized nanoporous zeolitic imidazole framework (ZIF-8) nanoparticles with a particle size of 60 nm and a pore size of 0.34 nm in water and directly added them into an aqueous solution of the organic polymer poly(vinyl alcohol) (PVA) without an intermediate drying process. This approach led to a high-quality PVA/ZIF-8 MMM with enhanced performance in ethanol dehydration by pervaporation. The permeability of this MMM is three times higher than that of pristine PVA, and the separation factor is nearly nine times larger than that of pristine PVA. The significantly improved separation performance was attributed to the increase in the fractional free volume in the membranes.

Towards Acid-Tolerated Ethanol Dehydration: Chitosan-Based Mixed Matrix Membranes Containing Cyano-Bridged Coordination Polymer Nanoparticles.

Prussian blue (PB) nanoparticles, one of many cyano-bridged coordination polymers, are successfully incorporated into chitosan (CS) polymer to prepare PB/CS mixed matrix membranes (MMMs). The PB nanoparticles are uniformly distributed in the MMMs without the collapse of the original PB structure. As-prepared PB/CS MMMs are used for ethanol dehydration at 25 °C in the pervaporation process. The effect of loading PB in CS matrix on pervaporation performance is carefully investigated. The PB/CS membrane with 30 wt% PB loading shows the best performance with a permeate flux of 614 g. m-2 . h-1 and a separation factor of 1472. The pervaporation using our PB/CS membranes exhibits outstanding performance in comparison with the previously reported CS-based membranes and MMMs. Furthermore, the addition of PB allows PB/CS MMMs to be tolerant of acidic environment. The present work demonstrates good pervaporation performance of PB/CS MMMs for the separation of an ethanol/water (90:10 in wt%) solution. Our new system provides an opportunity for dehydration of bioethanol in the future.

Synthesis of hierarchical micro/mesoporous structures via solid-aqueous interface growth: zeolitic imidazolate framework-8 on siliceous mesocellular foams for enhanced pervaporation of water/ethanol mixtures.

A new hierarchical micro/mesoporous composite is synthesized via direct growth of microporous zeolitic imidazolate framework-8 (ZIF-8) on siliceous mesocellular foams (MCF). Depending on different synthetic conditions, ZIF-8 with two different particle sizes, i.e., ZIF-8 microparticles and ZIF-8 nanoparticles, were successfully formed on the external surface of amine-functionalized MCF (denoted as microZIF-8@MCF and nanoZIF-8@MCF, respectively). The synthesized hierarchical micro/mesoporous ZIF-8@MCF structures were characterized with several spectroscopic techniques including X-ray diffraction (XRD), solid-state NMR, and FT-IR and electron microscopic techniques (scanning electron microscope, SEM, and transmission electron microscopy, TEM). In addition, the pervaporation measurements of the liquid water/ethanol mixture show that nanoZIF-8@MCF/PVA (poly(vinyl alcohol) mixed-matrix membrane exhibits enhanced performance both on the permeability and separation factor. Compared to conventional routes for chemical etching, this study demonstrates a promising and simple strategy for synthesizing novel hierarchical porous composites exhibiting both advantages of mesoporous materials and microporous materials, which is expected to be useful for gas adsorption, separation, and catalysis.