Ceramic Hollow Fiber Membrane Research Articles

A profound investigation into the viability of calcium bentonite as a new alternative ceramic material for the development of a highly porous ceramic hollow fiber membrane for the remediation of oily produced water

BackgroundCeramic hollow fiber membranes (CHFMs) have been recognized as an effective method in treating oily produced water (OPW). However, the high cost of CHFMs deters industries for implementing them on a large scale. MethodsThis research investigates the feasibility of using calcium bentonite as CHFMs for treating OPW and examines the effect of sintering temperatures on the physical properties, mechanical properties and performance of calcium bentonite hollow fiber membranes (CaB-HFMs). The calcium bentonite undergoes several pre-treatment processes and is subsequently characterized. The fabricated CaB-HFM with 45 wt% of calcium bentonite content (CaB-HFM 45) is characterized and examined for water permeation and OPW rejection performance in a cross-flow filtration mode for 3 h. Significant findingAmong the CaB-HFM 45, the membrane sintered at 1100 °C displayed optimum characteristics for OPW treatment, including a good morphology with adequate sponge-like and void-like pore structure, a mechanical strength of 95.33 ± 2.6 MPa, an average pore size of 1.015 µm and a porosity of 51.04%. Surprisingly, the membrane also displayed strong hydrophilic behavior (26.05°) and strong underwater oleophobic behavior (141.20°), resulting in outstanding water permeation performance (505.7 ± 29.5 L/m2.h.bar) and oil rejection performance of up to 97%. These remarkable features highlight the membrane's potential as a promising solution for OPW treatment.

Gravity-driven membrane reactor for decentralized wastewater treatment: Comparison of reactor configuration and membrane module

Gravity-driven membrane (GDM) filtration is an attractive option for decentralized wastewater treatment due to lower energy consumption. However, insufficient information is available on the design factors of GDM reactor. In this study, we investigated the impacts of membrane aeration, types of membrane modules, and biocarrier deposition onto the membrane on water quality and membrane performance of GDM reactors. In detail, the membrane air diffuser located inside the granular activated carbon (GAC)-biofilm zone had benefit for mass transfer of dissolved oxygen and achieving co-existence of anoxic and aerobic conditions in the reactor, leading to higher removal efficiencies for organics (93.8–94.6 %), nitrogen (38.2–47.2 %) and phosphorus (31.9–57.7 %), compared to the air diffuser located outside the GAC zone (90.3 % for organics, 25.3 % for nitrogen and 7.0 % for phosphorus). In addition, the inside-out ceramic hollow fibre membrane showed ∼150–200 % higher fouling resistance (mainly cake resistance) due to greater biopolymer deposition compared to the outside-in polymeric hollow fibre membrane. However, for the outside-in flat sheet configuration, the ceramic and polymeric membranes showed comparable fouling resistance. The deposition of GAC particles on the membrane surface as secondary layer could improve permeate water quality, but at the expense of an increase in irremovable fouling.

Robust omniphobic ceramic hollow fibre membrane with leaf-like copper oxide hierarchical structure by membrane distillation

Omniphobic membranes have recently shown promising performance in water desalination using MD due to their ability to repel all liquid drop types and keep the membrane surface dry. This study successfully modified the surface of robust hydrophilic mullite-stainless steel hollow fibre membranes (M-SS HFMs) to omniphobic properties. The omniphobic layer was achieved through surface grafting with copper oxide (CuO) rough layer by a hydrothermal technique at different hydrothermal reaction times of 1, 2, 3, 4 and 5 h, followed by fluorination step using 1H,1H,2H,2H-perfluorode-cyltriethoxysilane (C8, 97 %). Next, the omniphobic membranes were characterized in terms of membrane morphology, roughness, mechanical strength, pore size/distribution, liquid entry pressure, contact angle and fouling accumulation. The prepared omniphobic M-SS HFMs were also tested through the DCMD system at 80 °C using a feed solution containing 35 g/L of NaCl and 10 mg/L of humic acid as a foulant agent. The results indicated that M-SS HFMs subjected to a 4 h hydrothermal reaction time, resulting in a leaf-like surface structure, exhibited superior characteristics compared to other omniphobic HFMs reported in the literature that used titania (SiO2), zinc oxide (ZnO), and cobalt (Co3O4) as roughing material. These superior features included higher roughness of 0.798 μm, liquid entry pressure of 5.40 bar, and enhanced liquid repellence and contact angles towards DI water of 167°, olive oil of 152°, and ethanol of 145°. Additionally, the M-SS HFMs at 4 h hydrothermal demonstrated remarkable performance in terms of rejection performance (99.99 %) and vapour flux stability of about 29 kg/m2.h in DCMD operations, surpassing the performance of omniphobic HFMs fabricated using mullite-ball clay, mullite-kaolinite, and alumina (Al2O3). Notably, no fouling/wetting on the membrane surface and elements leaching was observed throughout the MD operation. These findings highlight the potential of this omniphobic HFM for seawater desalination using DCMD systems, even in the presence of organic contaminants.

Fabrication and characterization of a novel mullite-stainless steel composed hollow fibre membrane for oil/water separation

Low-cost mullite-kaolinite material has recently received more attention as an alternative to conventional ceramic materials such as alumina and silica to prepare ceramic hollow fibre membranes (CHFMs) due to its high alumina contents and silica and thermal/chemical stability. However, weak bending strength is still one of the key bottlenecks that delay their commercial applications. In this work, we successfully fabricate a novel mullite-SS HFM with enhanced bending strength using mullite-kaolinite power with different stainless steel alloy (SS) 316 L contents of 0.0, 2.5, 5.0, 7.5, 10 and 12 % (w/w) as a reinforcement material by phase inversion/sintering techniques. The SS alloy was a potential material to enhance the mechanical strength of mullite HFMs due to its excellent mechanical properties. The effects of the major fabrication parameters of SS contents, mullite contents, and fabrication parameters such as air gap distance and bore fluid flow rates were well studied and evaluated through the fabrication process. Fabricated mullite-SS HFMs were characterized by morphology, porosity, pore size/pore size distribution, and bending strength. Afterwards, they were evaluated in an oil/water separation system regarding water flux and oil rejection rate. Based on the findings, there was a gradual increase in the bending strength from 32.1 to 79.8 MPa with increased SS contents from 0 to 12 % (w/w). At 10 % (w/w) SS, the satisfactory morphology with the balance between the bending strength of 66.7 MPa and porosity of 29 % was obtained. This bending strength was significantly higher than reported for mullite-kaolinite HFMs in previous works. Moreover, At 10 % (w/w) SS, the oil–water rejection performance of 96.9% and the water permeation of 290 L/m2. h was satisfactory at the sintering temperature of 1300 °C. These findings suggest the advantage of this membrane for various water treatment applications, such as oil/water separation, due to its outstanding physical properties.

Investigation on the Performance of CO2 Absorption in Ceramic Hollow-Fiber Gas/Liquid Membrane Contactors.

The absorption efficiencies of CO2 in ceramic hollow-fiber membrane contactors using monoethanolamine (MEA) absorbent under both cocurrent- and countercurrent-flow operations were investigated theoretically and experimentally; various MEA absorbent flow rates, CO2 feed flow rates, and inlet CO2 concentrations were used as parameters. Theoretical predictions of the CO2 absorption flux were analyzed by developing the mathematical formulations based on Happel's free surface model in terms of mass transfer resistances in series. The experiments of the CO2 absorption were conducted by using alumina (Al2O3) hollow-fiber membranes to confirm the accuracy of the theoretical predictions. The simplified expression of the Sherwood number was formulated to calculate the mass transfer coefficient of the CO2 absorption incorporating experimental data. The data were obtained numerically using the fourth-order Runge-Kutta method to predict the concentration distribution and absorption rate enhancement under various fiber packing configurations accomplished by the CO2/N2 stream passing through the fiber cells. The operations of the hollow-fiber membrane contactor encapsulating N = 7 fiber cells and N = 19 fiber cells of different packing densities were fabricated in this work to examine the device performance. The accuracy derivation between experimental results and theoretical predictions for cocurrent- and countercurrent-flow operations were 1.31×10-2≤E≤4.35×10-2 and 3.90×10-3≤E≤2.43×10-2, respectively. A maximum of 965.5% CO2 absorption rate enhancement was found in the module with embedding multiple fiber cells compared with that in the device with inserting single-fiber cell. Implementing more fiber cells offers an inexpensive method of improving the absorption efficiency, and thus the operations of the ceramic hollow-fiber membrane contactor with implementing more fiber cells propose a low-priced design to improve the absorption rate enhancement. The higher overall CO2 absorption rate was achieved in countercurrent-flow operations than that in cocurrent-flow operations.

Fabrication of low-cost granite dust ceramic hollow fibre membrane: Effects of sintering temperature

Ceramic hollow fibre membrane (CHFM) is associated with many advantages such as better mechanical and thermal stabilities. However, the cost of the CHFM is very high owing to expensive raw materials and high sintering temperature. In this study, granite dust, a waste from stone industry was selected as a raw material to reduce the cost of ceramic membrane. The influence of sintering temperature on the physical properties of granite dust CHFM (GD-CHFM) was also investigated. The GD was subjected to XRD, XRF, and TGA analysis in order to understand the psychochemical properties of the GD. The GD-CHFM was prepared via a phase inversion and sintering method. Then, the GD-CHFM precursors were sintered at various temperature ranging between 1050 °C and 1150 °C. The effects of sintering temperature on the morphology, porosity and mechanical strength were systematically investigated. From the SEM images, the membranes exhibited symmetric structure where the average grain sizes were found to increase with sintering temperature. It was also realized that when the sintering temperature exceeded 1150 ℃, the GD-CHFM starts to melt. The volumetric porosity was found to decrease with sintering temperature due to the densification of pores. The increased in bending strength can be related with the decreasing of porosity in the sintered GD-CHFM. The mechanical strength of GD-CHFM sintered at 1150 °C was comparable with the CHFMs sintered at higher temperature (greater than 1400 °C). This indicates that the cost of GD-CHFM production can be reduced significantly, making it economically attractive for the future commercialization of GD-CHFM.

Two-dimensional Fe3O4-MnO2 hollow fiber ceramic membrane for hybrid catalytic ozonation-membrane filtration process for TCH degradation

In this work, a novel 2D Fe3O4-MnO2 hollow fiber ceramic membrane (HFCM) with both excellent separation performance and high catalytic activity was constructed. The Fe3O4 nanoparticles were deposited on 2D MnO2 nanoplates to increase the Mn3+ content, and then the nanoplates were pressure-driven and sintered on the surface of the hollow fiber ceramic supports to obtain 2D Fe3O4-MnO2-HFCMs. Electron spin resonance analysis confirmed that hydroxyl radicals and superoxide radicals played a major role in oxidative degradation and tetracycline hydrochloride (TCH) removal was 86.9 %. Noteworthily, TCH was concentrated on the membrane interface due to the concentration polarization effect, which increases the probability of binding free radicals from the catalytic membrane layer, thus enhancing the catalytic performance and the anti-fouling capability of the membrane. The 2D Fe3O4-MnO2-HFCM can be applied in wastewater treatment due to its superior catalytic ozonation activity and high separation performance.

Surface functionalization of bauxite hollow fibre membrane using copper oxide (CuO) and its reusability for photodegradation of bisphenol A from aqueous solution

This work developed and applied a CuO-impregnated bauxite hollow fibre membrane (BHFM) using hydrothermal method for bisphenol A (BPA) photodegradation. BHFM was synthesized through a phase inversion method at optimum sintering at 1300 °C. Subsequently, the physico-chemical properties of CuO-coated BHFM were characterized, while its performance for the BPA degradation was investigated at varying time of hydrothermal exposure and compared to ceramic hollow fibre membrane from alumina (AHFM) as control and commercial membranes. Oxidation by-products, resulting from BPA photodegradation, were identified and after treatment, the saturated membrane was regenerated to sustain its cost-effectiveness. As compared to the pristine BHFM membrane, we found that functionalizating BHFM surface with CuO significantly improved its mechanical strength by 130 % from 18.5 to 42.5 MPa. The removal of BPA was enhanced with the increasing hydrothermal time to 5 h due to the even distribution of CuO-impregnated BHMF on its membrane surface. 97 % of BPA removal with 10 mg/L concentration was substantially attained by the same CuO-impregnated BHFM under visible light (VIS) irradiation. Treated effluents, resulting from the BPA photocatalysis, could meet the required effluent limit of 20 mg/L set by national legislation. The possible oxidation by-products cover 4-(2-hydroxy-2-propanol)phenol, 4-isopropylphenol and dihydroxybenzene. With 25 % of efficiency, the saturated CuO-impregnated BHMF was subsequently regenerated for consecutive five cycles. This implies that functionalizing BHMF surface with CuO enabled it to possess outstanding stability and removal performance for treatment of BPA-laden wastewater.

Successful removal of phenol from industrial wastewater using novel hydrophobic modified ceramic hollow fiber membrane contactors with remarkably high stability

Wastewater pollution has become a serious global issue in recent years. One of the most prevalent industrial wastewater contaminants is phenol, a hazardous aromatic organic molecule. Part of the answer is to promote novel technologies for reducing the quantity of phenol (PH) in industrial wastewater. The liquid–liquid (LL) PH extraction process through a hydrophobically modified ceramic (Al2O3) hollow fiber (Al2O3HF) membrane contactor from an aqueous solution with a high initial concentration of PH (3500 ppm) was studied for the first time. Al2O3HF membranes were prepared by a combined phase-inversion and sintering process. All membranes were fully characterized. PH extraction process tests were performed at a temperature range from room temperature to 50 °C. Under room temperature conditions, the total PH extraction (%) was 80 % with respect to the initial PH concentration. The total PH extraction (%) increases as the temperature increases, reaching a value of about 91 % at 50 °C. The durability of the Al2O3HF membrane contactor during a long-term LL PH extraction was investigated at 40 °C. The Al2O3HF membrane contactor exhibited no degradation in LL PH removal ability after a 100-hour LL PH extraction operation.

Nickel-Coated ceramic hollow fiber cathode for fast enrichment of chemolithoautotrophs and efficient reduction of CO2 in microbial electrosynthesis

Microbial electrosynthesis (MES) explores the potential of chemolithoautotrophs for the production of value-added products from CO2. However, the enrichment of chemolithoautotrophs on a cathode is relatively slow and the separation of the products is energy intensive. In this study, a novel and multifunctional cathode configuration, enabling the simultaneous enrichment of chemolithoautotrophs and separation of acetate from MES, was developed through one-step electroless nickel plating on ceramic hollow fiber (CHF) membrane. A thick layer of chemolithoautotrophs with 5.2 times higher cell density, which was dominated by Sporomusa (68 % of the total sequence reads in biocathode), was enriched on the membrane cathode surface through suspended biomass microfiltration compared to MES reactors operated without filtration. Simultaneously, >87 % of acetate (31 mM) per batch could be harvested after catholyte microfiltration. The Ni content was > 80 % on the CHF surface after long-term operation in the two-chamber MES system, which exhibited 78 % lower charge transfer resistance compared to three-chamber MES system (∼110 vs 510 Ω) for acetate separation/extraction. The ease of product separation in two-chamber MES systems and the fast establishment of chemolithoautotrophs on the cathode are a step forward in realizing MES systems as a promising platform for CO2 reduction and biochemical production in a circular carbon bioeconomy.

Novel approach to surface functionalization of mullite-kaolinite hollow fiber membrane using organosilane-functionalized Co3O4 spider web-like layer deposition for desalination using direct contact membrane distillation

This work investigated a novel omniphobic mullite ceramic hollow fiber membrane (MCHFM) with low fouling and wetting propensity for use in direct contact of membrane desalination (MD) processes. The MCHFM was surface-coated with a spider web-like (SWL) cobalt oxide (Co3O4) rough layer via hydrothermal method at different reaction time (10, 13, 16, and 19 h) before a fluorination step using 1H,1H,2H,2H-perfluorodecyltriethoxysilane (97%) (FAS-17). After surface modification, the synthesized super hydrophilic membrane became highly repellent to water and other low surface tension liquids such as olive oil and engine oil with 32 and 31 mN/m of force, respectively. The surface-modified omniphobic membrane showed super-omniphobic properties towards engine oil at 154°, deionized water at 165°, and near superomniphobicity at 142.1° towards olive oil. The hydrothermal reaction time of the omniphobic membranes was studied using the DCMD test at 60 °C, while utilizing 30 g/L of NaCl and 8 mg/L of humic acid as feed. It was found that the hydrothermal reaction time at 16 h/FAS (Hy-16h/FAS) achieved a long-term stability as the rejection rate and water flux values were relatively constant (99.99%) and 22.8 kg/m2.h for about 4.3 h of the MD process. SEM analysis showed no fouling on the surface modified membrane. This was attributed to the Co3O4 spider web-like particles, which achieved superior anti-fouling properties. This implied the suitability of the fabricated omniphobic MCHFM with a SWL structure for DCMD and seawater desalination, in spite of organic contaminants.

Hot-Water Hemicellulose Extraction from Fruit Processing Residues.

Hemicelluloses are an abundant biopolymer resource with interesting properties for applications in coatings and composite materials. The objective of this investigation was to identify variables of industrially relevant extraction processes that increase the purity of hemicelluloses extracted from fruit residues. Our main finding is that extraction with subcritical water, followed by precipitation with alcohol, can be adjusted to yield products with a purity of at least 90%. Purity was determined based on the total concentration of glucose, galactose, xylose, arabinose, and mannose after hydrolysis with sulfuric acid. In the first experimental design (DoE methodology), the effects of extraction temperature (95–155 °C) and time (20–100 min) on yield and purity were studied. A clear trade-off between yield and purity was observed at high temperatures, indicating the selective removal of impurities. In the second experimental design, the influence of extract pH and alcohol concentration on yield and purity was investigated for the raw extract and a concentrate of this extract with 1/6 of the original volume. The concentrate was obtained by ultrafiltration through ceramic hollow-fiber membranes. The highest purity of 96% was achieved with the concentrate after precipitating with 70% alcohol. Key factors for the resource efficiency of the overall process are addressed. It is concluded that extraction with subcritical water and ultrafiltration are promising technologies for producing hemicelluloses from fruit residues for material applications.

Hydrophobic silica sand ceramic hollow fiber membrane for desalination via direct contact membrane distillation

A porous hollow fibre ceramic membrane derived from a low-cost natural material (silica sand) and fabricated by combine phase inversion and sintering technique followed by fluoroalkylsilane (FAS17) grafting to improve its hydrophobicity is reported in this study. Prior to the subjection of the silica sand ceramic hollow fibre membrane (SSCHFM) to a desalination performance test via direct contact membrane distillation (DCMD), characterization studies were performed on the SSCHFM before and after grafting using different characterization techniques, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), 3-points bending, water liquid entry pressure (LEPw), and water contact angle measurement. Mercury porosimetry analysis (MIP) was also used to determine the pore size distribution and porosity of the SSCHFM. The grafting process caused an increasing of the contact angle from 0° to 142.5° ± 2.0, and LEPw value of (2.6 ± 0.4 bar) was achieved. AFM images showed an increment in the surface roughness of the grafted SSCHFM from 0.305 µm to 0.375 μm, with a slight decrease in the average pore size and porosity from 0.17 µm and 17% to 0.12 µm and 14.7% respectively. After the grafting process, the performance of the membrane in DCMD was evaluated on a salt solution for 32 h at different NaCl concentrations (8,16, 24, 32 and 40) g/L, feed flow rates and feed temperatures. The results showed a decrease in the permeate flux at increasing feed concentration, but the reverse was at higher feed flow rates and feed temperatures. The surface-modified membrane recorded a water flux value of 35 kg/m2.h and 100% salt rejection. The results indicate that the hydrophobic hollow fibre ceramic membranes derived from silica sand have significant potential to be developed for membrane distillation application in water purification and reclamation.

Omniphobic surface modification of silica sand ceramic hollow fiber membrane for desalination via direct contact membrane distillation

Omniphobic silica sand ceramic hollow fiber membrane (SCHFM) was successfully fabricated for the reduction of the wetting and fouling in direct contact membrane distillation (DCMD). Surface functionalization of the laboratory spun SCHFM was performed following a series of steps 1) deposition of spherical silica nanoparticles (SiNPs), 2) fluorination by 1H,1H,2H,2H perfluorodecyltriethoxysilane (FAS17) and 3) poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) coating to glue SiNPs to the SCHFM surface. Initially, the pristine SCHFM was hydrophilic, but when the surface modification was fully applied the hollow fiber became omniphobic, exhibiting high contact angles for all tested liquids of different surface tensions, such as distilled water, red palm oil and ethanol. For example, one of the surface modified hollow fibers, called SiNPs-FAS-PVDF/FAS, was superomniphobic toward water (167°) and red palm oil (157°), and near superomniphobic toward ethanol (146.1°). As for the DCMD experiments with the feed solution containing 35 g/L NaCl and 10 mg/L humic acid, two of the surface modified hollow fibers, called SiNPs-PVDF/FAS and SiNPs-FAS-PVDF/FAS, showed high anti-fouling and anti-wetting resistance during the entire DCMD operation period of 400 min with little flux reduction and no observable increase in the conductivity of the permeate stream. The anti-fouling resistance of these hollow fibers was further evidenced by the cleanness of the surface in the micrographic picture taken after the DCMD run. The omniphobicity of these hollow fibers is ascribed to the combined effects of surface tension decrease by the FAS17 fluorination and the formation of the re-entrant structure by the densely packed SiNPs. With reasonably high fluxes of 35.1 kg/m2∙h and 43.6 kg/m2∙h, for SiNPs-PVDF/FAS and SiNPs-FAS-PVDF/FAS, respectively, and 100% of salt rejection, these hollow fibers have potential for seawater desalination by DCMD.

Superhydrophobic ball clay based ceramic hollow fibre membrane via universal spray coating method for membrane distillation

In this work, the feasibility study of a superhydrophobic ball clay based ceramic hollow fibre membrane (HFM) through pre-fluorinating of poly(vinylidene fluoride)–co-hexafluoropropylene (PVDF-HFP) and ZnO nanoparticles composite with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (C8) followed by post-roughening on fluorinated ball clay based ceramic hollow fibre membrane (PH/C8/ZnO-C8/HFM) via universal spray coating. The coating was applied onto ball clay based ceramic hollow fibre membrane’s surface in order to achieve superhydrophobicity, which had not previously been reported. C8 was grafted on the ceramic hollow fibre membrane’s surface using the conventional immersion method and the prepared membrane (C8/HFM) was served as a control. The hierarchical structure of PH/C8/ZnO-C8/HFM is composed of a cooperative layer of fluorinated PVDF-HFP/ZnO nanocomposite in mechanical interlocking mode. PH/C8/ZnO-C8/HFM has better superhydrophobic properties, with a water contact angle of 154.4° and a hysteresis contact angle of 3.2°, than C8/HFM, which has a water contact angle of 151.7° and a hysteresis contact angle of 9.2°. The PH/C8/ZnO-C8/HFM outperforms the C8/HFM in the wetting resistance because the liquid entry pressure of water LEPw (PH/C8/ZnO-C8/HFM = 1.33 ± 0.4 bar, C8/HFM = 0.37 ± 0.1 bar) and salt rejection in MD for the PH/C8/ZnO-C8/HFM is better than C8/HFM.

Construction of MoS2 hybrid membranes on ceramic hollow fibers for efficient dehydration of isopropanol solution via pervaporation

Due to environmental issues and intense competition in the marketplace, industries and governmental organizations invest in new technology research to improve productivity, environmental protection, and cost-efficiency. Pervaporation is a membrane-based separation technology, which is cost-effective, environmentally friendly, and efficient in the separation of azeotropic mixtures. Here, we report the fabrication of a hybrid membrane based on molybdenum disulfide (MoS2) material, which can be used to dehydrate alcohol through a pervaporation process. Ceramic hollow fiber (CHF) membrane was used as a substrate in MoS2hybrid membrane, and TiO2 intermediate layer was constructed to reduce the macropores on the CHF surface. Polyethyleneimine (PEI) was used as a binder in the fabrication of the MoS2 layer. MoS2-PEI layer was prepared by vacuum suction method and then crosslinked with trimesoyl chloride (TMC) to prevent the hybrid layer from swelling in an aqueous solution. We investigated the morphology and physicochemical characteristics of the hybrid membranes by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and water contact angle (WCA) measurements. The fabricated MoS2hybrid membrane possesses a permeation flux of 5697 g m-2h−1 and separation factor of 320 in a 90 wt% isopropanol aqueous solution at 343 K. In this study, we provide a comprehensive understanding of the fabrication of MoS2hybrid membrane on the CHF membrane for efficient dehydration of isopropanol via the pervaporation process.

Oxygen permeation simulation of La0.8Ca0.2Fe0.95O3−δ‐Ag hollow fiber membrane at different modes and flow configurations

AbstractMixed ionic‐electronic conducting La0.8Ca0.2Fe0.95O3−δ‐Ag (LCF‐Ag) ceramic hollow fiber membranes possess high structural stability and up to 2.24‐fold higher oxygen permeation fluxes relative to LCF hollow fibers. In this work, the oxygen permeation of LCF‐Ag hollow fiber membrane module is simulated under sweep gas and vacuum operation modes, whereas the kinetic parameters were obtained by fitting the experimental data with the simplified Tan–Li model. The good correlation obtained from the data regression confirmed the compatibility of the selected model on the LCF‐Ag hollow fiber membrane. The simulated results revealed that the countercurrent flow configuration is generally favored in sweep gas operation given its potential of complete oxygen separation under optimized conditions. For vacuum operation, the oxygen yield is practically the same for both flow configurations at a moderate vacuum setting. At a very low vacuum pressure setting, however, cocurrent flow is preferred over countercurrent flow for maximizing the oxygen yield.

SUZ-4 zeolite membrane fabricated by dynamic hydrothermal crystallization for pervaporation separation of MeOH/MMA mixture

The SUZ-4 zeolite membrane was prepared on the hollow fiber ceramic membrane via the secondary growth method modified by the dynamic hydrothermal process. The surface morphology and pervaporation (PV) performance of zeolite membranes fabricated by dynamic and static hydrothermal processes were studied. The surface of the zeolite membrane prepared by the dynamic hydrothermal process was covered with rod-shaped crystals, while the static one was full of crystal clusters fabricated by small-sized crystals. Besides, the separation factor of the SUZ-4 zeolite membrane made via dynamic hydrothermal method for separating 10 wt% methanol (MeOH)/methyl methacrylate (MMA) mixture at 50 °C exceed 10000 with a flux of 3.83 kg·m−2·h−1, which was better than the static one and showed excellent long-term stability. This work provided the important assistance for the preparation of SUZ-4 zeolite membranes in the separation of MeOH/MMA and MeOH/dimethyl carbonate (DMC) organic mixtures and demonstrated the great potential of dynamic process in promoting the membrane properties.

Low-cost silica based ceramic supported thin film composite hollow fiber membrane from guinea corn husk ash for efficient removal of microplastic from aqueous solution

In this study, an economic silica based ceramic hollow fiber (HF) microporous membrane was fabricated from guinea cornhusk ash (GCHA). A silica interlayer was coated to form a defect free silica membrane which serves as a support for the formation of thin film composite (TFC) ceramic hollow fiber (HF) membrane for the removal of microplastics (MPs) from aqueous solutions. Polyacrylonitrile (PAN), polyvinyl-chloride (PVC), polyvinylpyrrolidone (PVP) and polymethyl methacrylate (PMMA) are the selected MPs The effects of amine monomer concentration (0.5 wt% and 1 wt%) on the formation of poly (piperazine-amide) layer via interfacial polymerization over the GCHA ceramic support were also investigated. The morphology analysis of TFC GCHA HF membranes revealed the formation of a poly (piperazine-amide) layer with narrow pore arrangement. The pore size of TFC GCHA membrane declined with the formation of poly (piperazine-amide) layer, as evidenced from porosimetry analysis. The increase of amine concentration reduced the porosity and water flux of TFC GCHA HF membranes. During MPs filtration, 1 wt% (piperazine) based TFC GCHA membrane showed a lower transmission percentage of PVP (2.7%) and other suspended MPs also displayed lower transmission. The impact of humic acid and sodium alginate on MPs filtration and seawater pretreatment were also analyzed.

Effects of Operating and Structural Parameters on Removal of Nitric Oxide by Oxidation in a Ceramic Hollow Fiber Membrane Contactor

A numerical study on the oxidation removal of nitric oxide in a ceramic hollow fiber membrane contactor was performed. To represent the transport and absorption process, the model was created by combining multiphase, species, reaction, and porous models. The numerical results were verified by comparing them with experimental data. The tube and lumen sides both have laminar parabolic velocity distributions. The nitric oxide concentration decreases gradually from the membrane wall to axis at the cross-section except on the inner and outer sides of the membrane tube. The equivalent diffusion length was proved useful for evaluating the entrance effect. At low concentrations, the reduction efficiency was proportional to the absorbent concentration, and at large concentrations, it neared a maximum value. The reduction efficiency was positively affected by elevated operating temperature and pressure. With a gas channel width of 13 mm, the reduction flow rate achieves its maximum. The efficiency of NO reduction per area decreases as the effective membrane length increases. Increasing the operating temperature and membrane length are recommended as design priorities due to high relative enhancements. It is not recommended to improve reduction efficiency by increasing membrane tube diameter and operating pressure in design. Changing the gas flow rate, absorbent concentration and gas channel width are moderate recommended as well.