Gas permeation through water‐swollen polysaccharide/poly(vinyl alcohol) membranes

The effect of Na‐alginate content on the gas permeation properties of water‐swollen membranes prepared by varying Na‐alginate and poly(vinyl alcohol) (PVA) content in membranes was investigated. The influences of water content and crystallinity of the membranes on the gas permeation performance of the water‐swollen membranes were studied. The gas permeation rate and selectivity of Na‐alginate/PVA water‐swollen membranes were compared with those of the dry membranes. The permeation rates of nitrogen and carbon dioxide through water‐swollen membranes were in the range of 0.4–7.6 × 10^?7 to 3.7–8.5 × 10^?6 cm³ (STP)/cm² s^?1 cmHg^?1, which were 10,000 times higher than those of dry‐state membranes. The permeation rates of mixture gases through water‐swollen Na‐alginate/PVA membranes were found to increase exponentially with the increase of Na‐alginate content, whereas carbon dioxide concentration in permeates was decreased linearly. It was found that the gas permeance of the water‐swollen membranes increased with increasing the Na‐alginate content in the membrane. Gas permeation rates of the water‐swollen Na‐alginate/PVA membranes increased with increasing the water content in the membrane and decreasing the crystallinity of the membrane. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3225–3232, 2004     

Improvement of porous polyvinylidene fluoride-co-hexafluropropylene hollow fiber membranes for sweeping gas membrane distillation of ethylene glycol solution

Porous polyvinylidene fluoride-co-hexafluropropylene (PVDF-HFP) hollow fiber membranes were fabricated through a wet spinning process. In order to improve the membrane structure, composition of the polymer solution was adjusted by studying ternary phase diagrams of polymer/solvent/non-solvent. The prepared membranes were used for sweeping gas membrane distillation (SGMD) of 20 wt% ethylene glycol (EG) aqueous solution. The membranes were characterized by different tests such as N₂ permeation, overall porosity, critical water entry pressure (CEP_w), water contact angle and collapsing pressure. From FESEM examination, addition of 3 wt% glycerol in the PVDF-HFP solution, produced membranes with smaller finger-likes cavities, higher surface porosity and smaller pore sizes. Increasing the polymer concentration up to 21 wt% resulted in a dense spongy structure which could significantly reduce the N₂ permeance. The membrane prepared by 3 wt% glycerol and 17 wt% polymer demonstrated an improved structure with mean pore size of 18 nm and a high surface porosity of 872 m⁻¹. CEP_w of 350 kPa and overall porosity of 84% were also obtained for the improved membrane. Collapsing pressure of the membranes relatively improved by increasing the polymer concentration. From the SGMD test, the developed membrane represented a maximum permeate flux of 28 kg·m⁻²·h⁻¹ which is almost 19% higher than the flux of plain membrane. During 120 h of a long-term SGMD operation, a gradual flux reduction of 30% was noticed. In addition, EG rejection reduced from 100% to around 99.5% during 120 h of the operation.     

Enhanced desalination performance and arsenate removal using semi-aromatic polyamide-based pervaporation membranes by modifying with amino-acids via interfacial polymerization

In this study, the semi-aromatic polyamide membranes were synthesized by the interfacial polymerization between piperazine (PIP) monomers in the water phase and Benzene-1,3,5-tricarbonyl chloride in the organic phase. To further modify the semi-aromatic pervaporation membrane, the two amino acids, glycine, and l -lysine, were mixed with PIP monomers for interfacial polymerization. The morphology and physicochemical properties of the synthesized membranes were analyzed using Fourier transform infrared (FTIR), field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), and contact angle measurements. The results show that the semi-aromatic polyamide membranes modified by the two amino acids possess a higher hydrophilic surface and lower thickness compared to the unmodified membrane. Additionally, the permeation flux of the semi-aromatic polyamide membranes was improved by 18.6% and 38.5% as modified with glycine and l -lysine, respectively, at the operating temperature of 70°C when the rejection of both NaCl and arsenic are higher than 99.8%. Furthermore, the operating temperature significantly influenced the permeation flux, while the salt rejections were insignificantly affected. The permeation flux increases by 3.2- and 4.0-folds for glycine and lysine-modified membranes, respectively, when elevating the feed temperature from 40°C to 70°C. The highest permeation flux of 29.5 kg m⁻² h⁻¹ with a 5 wt% NaCl rejection of 99.8% was obtained at 70°C by using 0.3 wt% l -lysine modified polyamide (PA) membrane. For elimination of 1.5 mg L⁻¹ As solution at the feed temperature of 70°C, such l -lysine modified PA membrane exhibited the permeation flux of 30.5 kg m⁻² h⁻¹ and As rejection of 99.6%, respectively. This work provides a cost-saving, facile, and eco-friendly preparation method for effectively improving the permeation flux while not sacrificing the high rejection of salts of the modified membranes.     

Pervaporation of Acetaldehyde Aqueous Solution through Zeolite 3A-Polyurethane (PU) Composite Membrane

3A-filled hydrophilic polyurethane (PU) membranes were prepared by incorporating zeolite 3A into PU for pervaporation separation of acetaldehyde and water mixtures (acetaldehyde concentration 2 wt%–20 wt%). The composite membranes were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The morphology and thermal stability of these membranes were also investigated. The effects of zeolite 3A on the sorption, diffusion, and pervaporation performance were evaluated. The swelling study showed that 3A-PU membrane had higher swelling degree in acetaldehyde aqueous solution than in pure water. And the swelling degree of the composite membrane in acetaldehyde solution increased with the 3A content. The permeation flux and water/acetaldehyde separation factor first increased and then decreased with increasing 3A content. The reason may be that a proper quantity of 3A will enlarge the free volume fraction of PU while excessive 3A lead to its poor dispersion. The highest permeation flux of the composite membrane could reach 223 g · m^?2 · h^?1 and the maximum water/acetaldehyde selectivity achieved 7.5. The calculation of sorption selectivity and diffusion selectivity showed that diffusion played a more important role in this process.     

Highly efficient monovalent ion transport enabled by ionic crosslinking-induced nanochannels

Charge-governed ion transport is of significant importance to industrial development, and advanced membrane materials with fast and selective ionic transport are essential components. In cell membranes, ionic transport is mainly determined by the charge-governed protein channels, representing an architecture with functional differentiation. Inspired by this, a novel class of membranes was developed by ionically crosslinking sulfonated (poly[ether ether ketone]) and quaternized poly(2,6-dimethyl-1,4-phenylene oxide) to construct the cationic conductive biomimetic nanochannels. Ionic crosslinking was tailored to realize nanophase separation and efficient ion transport mainly based on surface chemistry without altering the scaffold feature of polymeric pore channels. The best-performing ionic crosslinking membrane exhibited a high ionic permeation (2.23 mol·m⁻²·h⁻¹ for K⁺) and high cationic selectivity (7.91 for K⁺/Mg²⁺), which were comparable with the commercial monovalent cation permselective CIMS membrane, owing to the negligent surface resistance toward monovalent cations but strong positively charged repulsion against divalent cations.     

Effect of embedding MWCNT-g-GO with PVC on the performance of PVC membranes for oily wastewater treatment

Abstract

In this work, polyvinyl chloride/multi-walled carbon nanotube-grafted-graphene oxide (PVC/MWCNT-g-GO) membranes were fabricated by employing a classical phase inversion method for use in the Al-Dura Refinery (Baghdad, Iraq) wastewater treatment. The effects of MWCNT-g-GO contents on the properties and performance of PVC/MWCNT-g-GO membranes (i.e., 0.0599, 0.119, and 0.219?wt.%) were investigated. Scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), contact angle (CA), porosity, and mechanical properties were used to characterize the MWCNT-g-GO and composite membranes. The membrane performance was characterized by liquid permeation flux and chemical oxygen demand (COD) rejection. The SEM and AFM results showed significant effects of MWCNT-g-GO on the structural morphology of the membranes. Also, it was found that the addition of a 0.119?wt.% MWCNT-g-GO membrane greatly improved the CA and porosity, from 74.5° to 13.9° and from 69.3% to 81.4%, respectively. Adding 0.219?wt.% of MWCNT-g-GO to the casting solution produced a major positive impact in the membrane mechanical properties. With 0.119?wt.% of MWCNT-g-GO (e.g., 254?L/m²·h), the membrane fostered increases in the water permeation flux that were 66% greater than when using the neat PVC (e.g., 153?L/m²·h). The COD rejection of the prepared membranes also improved significantly, from 60% for neat PVC to 88.9% after adding 0.119?wt.% of MWCNT-g-GO.     

Metal ion permeation properties of silk fibroin/chitosan blend membranes

Silk fibroin/chitosan (SF/CS) blend membranes were prepared and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy. It was found that SF and CS were compatible in the blend membranes and that the membranes were dense without microscopic phase separation. Swelling experiments showed that the swelling ratio of the blend membranes increased with CS content and reached the highest value when CS content was 70 wt%. Experiments indicated that the permeability coefficient of K⁺ through the blend membrane was 2–4 times higher than that of pure CS membrane, and 10 times higher than that of pure SF membrane. The permeation rate of K⁺ increased linearly with CS content in the blend membrane for the lower concentration feeding solution. For different metal ions, the permeability through SF/CS blend membranes was in the sequence K⁺ > Ca²⁺ > Cd²⁺ > Pb²⁺ > Cu²⁺ > Ni²⁺. Copyright © 2006 Society of Chemical Industry     

New high permeable polysulfone/ionic liquid membrane for gas separation

In this study, the effects of 1-Ethyl-3-methylimidazolium tetrafluoroborate ionic liquid on CO₂/CH₄ separation performance of symmetric polysulfone membranes are investigated. Pure polysulfone membrane and ionic liquid-containing membranes are characterized. Field emission scanning electron microscopy (FE-SEM) is used to analyze surface morphology and thickness of the fabricated membranes. Energy dispersive spectroscopy (EDS) and elemental mapping, Fourier transform infrared (FTIR), thermal gravimetric (TGA), X-ray diffraction (XRD) and Tensile strength analyses are also conducted to characterize the prepared membranes. CO₂/CH₄ separation performance of the membranes are measured twice at 0.3 MPa and room temperature (25 °C). Permeability measurements confirm that increasing ionic liquid content in polymer-ionic liquid membranes leads to a growth in CO₂ permeation and CO₂/CH₄ selectivity due to high affinity of the ionic liquid to carbon dioxide. CO₂ permeation significantly increases from 4.3 Barrer (1 Barrer=10^-10 cm³(STP)·cm·cm^-2·s^-1·cmHg^-1, 1cmHg=1.333kPa) for the pure polymer membrane to 601.9 Barrer for the 30 wt% ionic liquid membrane. Also, selectivity of this membrane is improved from 8.2 to 25.8. mixed gas tests are implemented to investigate gases interaction. The results showed, the disruptive effect of CH₄ molecules for CO₂ permeation lead to selectivity decrement compare to pure gas test. The fabricated membranes with high ionic liquid content in this study are promising materials for industrial CO₂/CH₄ separation membranes.     

Application of Pervaporation and Vapor Permeation Processes to Separate Aqueous Ethanoi Solution through Chemically Modified Nylon 4 Membranes

ABSTRACT

The pervaporation performance of a nylon 4 membrane, chemically grafted by N,N-dimethylaminoethyl methacrylate (DMAEM), DMAEM-g-N4, was studied by measurement of the permeation ratio and the pervaporation separation index. It was found that the water permselectivity and permeationrate for the chemically modified Nylon 4 membrane were higher than those of the unmodified Nylon 4 membrane. Optimum pervaporation results, a separation factor of 28·3, and a permeation rate of 439 g/m²-h, were obtained when the degTee of grafting was 12·7%. It was also found that all the permeation ratios at low temperature were less than unity. In addition, compared with pervaporation, vapor permeation effectively increases the permselectivity of water.     

Enhancement of NaA zeolite membrane properties through organic cation addition

Thin NaA zeolite membranes, with uniform and small crystals, were prepared on the tubular -Al₂O₃ support by adding a small amount of tetramethylammonium hydroxide (TMAOH) in the clear synthesis solution. The as-synthesized NaA zeolite membranes were characterized by XRD and SEM. The permeation properties of the membranes were evaluated by pervaporation and gas permeation. The effects of TMAOH amount on membrane formation and permeation properties were investigated. By addition of suitable amount of TMAOH in the clear synthesis solution, the crystals size of NaA zeolite could be remarkably reduced from about 10 μm to 3–4 μm, and the membrane thickness correspondingly reduced from about 16 μm to 5 μm. The thinner membrane prepared by adding TMAOH in the clear synthesis solution, with uniform and small crystal, displayed higher perm-selective properties than that without adding TMAOH. For the as-synthesized NaA zeolite membrane prepared with adding suitable amount of TMAOH (x = 1), the separation factor (water/isopropanol) was 4700 and the flux was 1.67 kg/(m² h), which were higher than that without adding TMAOH of 339 and 1.08 kg/(m² h), respectively. The ideal separation factor of H₂/N₂ was 6.60, higher than that without adding TMAOH of 3.41.     

钯复合膜的制备及其在氢气氮气分离中的应用

Thin palladium composite membranes were prepared by modified electroless plating method on a-alumina supports and a dense Pd/α-Al2O3 composite membrane with high hydrogen flux, good selectivity for hydrogen was obtained. It was tested in a single gas permeation system for hydrogen permeance and hydrogen selectivity over mtrogen. The hydrogen permeance of the corresponding membrane was ashigh as 2.45×10^-6mol·m^-2·s^-1.Pa^-1 and H2/N2 selectivityover700 at 623K and a pressure difference of 0.1MPa. The-main resistance of the composite membrane to H2 permeation lies in the aluminum ceramic support rather than the thin Pd layer.     

Dye derived and metal incorporated affinity poly(2-hydroxyethyl methacrylate) membranes for use in enzyme immobilization

Microporous poly(2-hydroxyethyl methacrylate) (PHEMA) membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (α,α′-azobisisobutyronitrile, AIBN). An affinity dye Cibacron Blue F3GA (CB) was attached covalently and then Fe³⁺ ions incorporated. The PHEMA-CB and PHEMA-CB-Fe³⁺ membranes derived were used for adsorption of glucose oxidase (GOD). The adsorption capacities of these membranes were determined under conditions of different pH and with different concentrations of the adsorbate in the medium. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The glucose oxidase adsorption capacity of the Fe³⁺ incorporated membrane (87μgcm^-2) was greater than that of the dye-derived membrane (66μgcm^-2). Non-specific adsorption of the glucose oxidase on the PHEMA membranes was negligible. The K_m values for both immobilized glucose oxidase PHEMA-CB-GOD (8·3) and PHEMA-CB-Fe³⁺-GOD (7·6) were higher than that of the free enzyme (6·2mM). Optimum reaction pH was 5·5 for the free and 6·0 for both immobilized preparations. The optimum reaction temperature of the adsorbed enzymes was 5°C higher than that of the free enzyme and was significantly broader. After 15 successive uses the retained activity of the adsorbed enzyme was 87%. It was observed that enzymes could be repeatedly adsorbed and desorbed on the derived PHEMA membranes without significant loss in adsorption capacity or enzymic activity. © 1998 SCI.     

Microporous polypropylene sheets containing polymethylsilsesquioxane filler

Plasma polymerized membranes were prepared from octamethyltrisiloxane for the purpose of separation of O₂ over N₂. The obtained membrane consisted of plasma prepared polymer layer on top of a porous polyproplene substrate. The membrane polymerized under the mild plasma condition (low power input and high monomer flow rate) showed the high permeation rate. Selectivity, however, was hardly affected by the plasma conditions. The selectivity and permeation rate obtained were 2.6 and 2.5 × 10^?10 kmol/(m²·s·Pa) (=7.5×10^?4 cm³/(cm²·s·cmHg)), respectively. This high permeation rate was attributed to the use of the monomer with the long, flexible siloxane chain and the mild plasma condition. Moreover, the membranes were prepared from a series of monomers with different siloxane chain lenghts (methoxytrimethylsilane, hexamethyldisiloxane, and octamethyltrisiloxane), and from those with different alkyl chain lenghts (methoxytrimethylsilane, propoxytrimethylsilane, and hexyloxytrimethylsilane). As the siloxane chain lenghts of the starting monomers increased and the alkyl chain lengths decreased, the permeation rates of the corresponding polymers increased. The selectivities were nearly constant regardless of the difference in the starting monomer structures. The structures of the plasma prepared polymers were analyzed by XPS and IR measurements, and discussed in relation to the membrane efficiencies. © 1994 John Wiley & Sons, Inc.     

The influence of metal oxides on the separation properties of hybrid alginate membranes

ABSTRACT

Alginate membranes filled with different metal oxide particles were prepared and the influence of the presence of different amounts of Fe₃O₄, ZnO, and Ag₂O particles on ethanol and water permeation was discussed. Ethanol and water vapour permeation rates were determined using the measuring cell method, and the mass transport coefficients were evaluated. It was found that the highest transport parameters were obtained for membranes with the highest metal oxide content. Furthermore, the highest flux, equal 8.49 kg·m^?2·h^?1, was obtained for the alginate membrane filled with 15 wt% of silver oxide particles, while the greatest selectivity coefficients were noted for membranes containing magnetite. In this case, for the alginate membrane with 15 wt% of magnetite content, the selectivity coefficient reached the best value of 108.15.     

Research on methanol permeation of proton exchange membranes with incorporating ionic liquids

Methanol permeation and conductivity of membrane materials are important factors to evaluate the feasibility of application as proton exchange membranes (PEMs) in direct methanol fuel cell (DMFC). The methanol permeation values of these composite membranes based on ionic liquids of trifluoroacetic propylamine (TFAPA) and the disubstituted imidazolium cations with different anions were summarized, and the methanol permeation behaviors were investigated in this work. Although these polymer/ionic liquid composite membranes displayed satisfactory conductivities, the relative selectivity values of conductivity to methanol permeability were lower than the value of Nafion^® membrane. Moreover, polymerized ionic liquids (PILs) membranes showed the strong ability to hinder methanol permeation with a value around 10^?11 cm²/s at 10 M methanol solution. The maximum relative selectivity value reached (2.23–1.76) × 10⁶ S·s/cm³ for PVC-MIMCl membrane, which was near two orders of magnitude higher than the reported 2.47 × 10⁴ S·s/cm³ for Nafion-117 membrane at 2 M methanol solution.

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Graphical abstract ?

     

Sulfonated poly(ether sulfone)/silica composite membranes for direct methanol fuel cells

A series of sulfonated poly(ether sulfone) (SPES)/silica composite membranes were prepared by sol–gel method using tetraethylorthosilicate (TEOS) hydrolysis. Physico–chemical properties of the composite membranes were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), scanning electron microscope–energy dispersive X‐ray (SEM–EDX), and water uptake. Compared to a pure SPES membrane, SiO₂ doping in the membranes led to a higher thermal stability and water uptake. SEM–EDX indicated that SiO₂ particles were uniformly embedded throughout the SPES matrix. Proper silica loadings (below 5 wt %) in the composite membranes helped to inhibit methanol permeation. The permeability coefficient of the composite membrane with 5 wt % SiO₂ was 1.06 × 10^?7 cm²/s, which was lower than that of the SPES and just one tenth of that of Nafion® 112. Although proton conductivity of the composite membranes decreased with increasing silica content, the selectivity (the ratio of proton conductivity and methanol permeability) of the composite membrane with 5 wt % silica loading was higher than that of the SPES and Nafion® 112 membrane. This excellent selectivity of SPES/SiO₂ composite membranes could indicate a potential feasibility as a promising electrolyte for direct methanol fuel cell. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fabrication of antifouling membranes by blending poly(vinylidene fluoride) with cationic polyionic liquid

Membrane fouling problem is now limiting the rapid development of membrane technology. A newly synthesized cationic polyionic liquid (PIL) [P(PEGMA-co-BVIm-Br)] was blended with poly(vinylidene fluoride) (PVDF) to prepare antifouling PVDF membranes. The PVDF/P(PEGMA-co-BVIm-Br) exhibited an increased surface hydrophilicity, the water contact angle was reduced from 77.8° (pristine PVDF) to 57.9°. More porous membrane structure was obtained by adding PIL into the blending polymers, as high as 478.0 L/m²·h of pure water flux was detected for the blend PVDF membrane in comparison with pristine PVDF (17.2 L/m²·h). Blending of the cationic PIL with PVDF gave a more positive surface charge than pristine PVDF membrane. Blend membranes showed very high rejection rate (99.1%) and flux recovery rate (FRR, 83.0%) to the positive bovine serum albumin (BSA), due to the electrostatic repulsion between the membrane surface and proteins. After three repeated filtration cycles of positive BSA, the blend PVDF membranes demonstrated excellent antifouling performance, the permeation flux of the membranes was recovered very well after a simple deionized water washing, and as high as 70% of FRR was obtained, the water flux was maintained at above 350 L/m²·h. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48878.     

Polyamide-based membranes consisting of nanocomposite interlayers for high performance nanofiltration

It is still a task to synthesize polyamide-based membranes with selective layers down to 10–20 nm for high performance desalination. Herein, cellulose nanocrystals (CNC) were used as one-dimensional (1D) nanorods and graphene oxides (GO) as two-dimensional (2D) nanosheets, respectively, to construct nanocomposite interlayers for synthesizing polyamide layers thinner than 15 nm. The 2D nanosheets are homogeneously mixed with the 1D nanorods and effectively reduce the surface roughness of the nanocomposite interlayers with decreasing the mass ratio of CNC/GO. Polyamide layers with a thickness of 10–15 nm have been synthesized at an ultralow monomer concentration of 0.025 wt% on these CNC/GO nanocomposite interlayers. The polyamide-based membranes exhibit extremely high water permeation (45.9 L/m²·h·bar) without losing their salt rejection ability. The nanofiltration performances of these polyamide-based membranes are higher than most of the reported nanofiltration membranes in recent years.     

Polyvinyl alcohol/polysulfone (PVA/PSF) hollow fiber composite membranes for pervaporation separation of ethanol/water solution

Polysulfone (PSF) hollow fiber membranes were spun by phase‐inversion method from 29 wt % solids of 29 : 65 : 6 PSF/NMP/glycerol and 29 : 64 : 7 PSF/DMAc/glycol using 93.5 : 6.5 NMP/water and 94.5 : 5.5 DMAc/water as bore fluids, respectively, while the external coagulant was water. Polyvinyl alcohol/polysulfone (PVA/PSF) hollow fiber composite membranes were prepared after PSF hollow fiber membranes were coated using different PVA aqueous solutions, which were composed of PVA, fatty alcohol polyoxyethylene ether (AEO₉), maleic acid (MAC), and water. Two coating methods (dip coating and vacuum coating) and different heat treatments were discussed. The effects of hollow fiber membrane treatment methods, membrane structures, ethanol solution temperatures, and MAC/PVA ratios on the pervaporation performance of 95 wt % ethanol/water solution were studied. Using the vacuum‐coating method, the suitable MAC/PVA ratio was 0.3 for the preparation of PVA/PSF hollow fiber composite membrane with the sponge‐like membrane structure. Its pervaporation performance was as follows: separation factor (α) was 185 while permeation flux (J) was 30g/m²·h at 50°C. Based on the experimental results, it was found that separation factor (α) of PVA/PSF composite membrane with single finger‐void membrane structure was higher than that with the sponge‐like membrane structure. Therefore, single finger‐void membrane structure as the supported membrane was more suitable than sponge‐like membrane structure for the preparation of PVA/PSF hollow fiber composite membrane. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 247–254, 2005     

A TiO2 modified whisker mullite hollow fiber ceramic membrane for high-efficiency oil/water emulsions separation

Design and preparation of membranes with ultrahigh separation performance and antifouling property for oil-in-water (O/W) emulsions remains challenging. In this study, a high flux mullite/TiO₂ ceramic composite membrane was prepared via multi-precipitation of TiO₂ on a whisker mullite hollow fiber support synthesized by combining phase inversion and high-temperature sintering techniques. The results showed that the generated whisker mullite structure improved the permeation flux, and the micro-nano structured TiO₂ functional layer endowed the membrane surface with superhydrophility and stability. The retention of the optimal composite membrane (M20T13) that was soaked in the titanium solution 20 times for 13 min each time for the O/W emulsions like n-hexane, toluene and engine oil maintained over 98 %, and the flux after 6 h filtration was 668.34 L·m⁻²·h⁻¹, 487.25 L·m⁻²·h⁻¹ and 258.66 L·m⁻²·h⁻¹, respectively, much higher than that of the optimal substrate (F3A1, mass ratio of fly ash: Al₂O₃ = 3:1). Moreover, the flux recovery rate of M20T13 was much higher than that of F3A1 after chemical backwashing. This work manifests great potential in O/W treatment fields.