Organic-inorganic Composite Membranes Research Articles

Polyacrylonitrile-based organic-inorganic composite anion-exchange membranes: Preparation, characterization and its application in making ion-selective membrane electrode for determination of As(V)

Organic–inorganic composite anion-exchange membranes based on polyacrylonitrile/silica gel were prepared by solution casting method in different stoicheometric ratios of polyacrylonitrile(PAN) and silica gel. The structure and morphology of the prepared membranes were ascertained by Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and elemental analysis (CHNS/O). The membrane having a composition 1:1 (PAN: silica gel) shows best results for ion-exchange capacity, water content, porosity, thickness and swelling. The As(V) selective electrode was developed by using this membrane for the determination of arsenate in solutions. The membrane electrode shows the best results with linear potential response in the concentration range of 1×10−1molL−1 to 1×10−6molL−1 of As(V) ion with a slope of 29.75mV/decade. The useful pH of the electrode is 5.0–10.0. The selectivity coefficients values for interfering ions indicate good selectivity for As(V) over interfering anions. The accuracy of the procedure has been tested on arsenic-free drinking water samples spiked with known amount of arsenate and results were comparable to these generated by PCA-Arsenomat (Arsenic Analyzer).

Transparent bacterial cellulose–boehmite–epoxi-siloxane nanocomposites

Organic–inorganic composite membranes were prepared from membranes of the bio-polymer bacterial cellulose (BC) and organic–inorganic sol composed of nanoparticulate boehmite and epoxi modified siloxane. Bacterial cellulose membranes are obtained in a highly hydrated state (1% cellulose and 99% cellulose) from cultures of Gluconacetobacter xylinus and could be used in the never-dried or in the dried state. Depending on the use of dried or never-dried BC membranes two main kinds of composites were obtained. In the first one dried BC membranes coated with the hybrid sol have lead to transparent membranes displaying a bi-phase structure where the two components could be easily distinguished, with individual structures preserved. A decrease was observed for tensile strength (50.5MPa) and Young’s Modulus (2.8GPa) when compared to pure BC membrane (112.5MPa and 12.7GPa). Elongation at break was observed to increase (2.5% against 1.5% observed for BC). When never-dried BC membranes were used transparent membranes were also obtained, however an improvement was observed for mechanical properties (tensile strength – 116MPa and Young’s Modulus – 13.7GPa). A lower value was obtained for the elongation at break (1.3%). In the last case the interaction between the two-phases lead to changes in the cellulose crystallinity as shown by X rays diffraction results. Multifunctional transparent membranes displaying the cellulose structure in one side and the boehmite–siloxane structure at the opposite face could find special applications in opto-electronics or biomedical areas taking advantage of the different chemical nature of the two components.

Carbonate and Tungstate Membranes of Nickel: Synthesis, Characterization, Diffusive Properties and Electrochemical Behavior

AbstractThe high thermal and chemical stability of inorganic-organic composite membranes make them desirable for applications in the environment as well as in food, pharmaceutical and many other industries. The permeability properties of inorganic membranes have been explored and their resemblance to biological systems has been utilized successfully.In the present study, a series of chloride salts (NH4Cl, KCl, NaCl and LiCl) were used to study the effect of counter-ion and co-ion species on membrane potential, measured across polystyrene based tungstate and carbonate membranes of nickel. The measurements had been carried out in order to evaluate the transport number of ions, mobility ratio, distribution co-efficient and permselectivity. The fixed charge densities of the membranes were calculated using Kobatake method. The two limiting forms of Kobatake's equation were used to evaluate various membrane parameters and the theoretical potentials calculated using this equation were compared with the experimental values and found a good accord between them which proved the applicability of the derived relationship to the membrane system. The thermodynamically effective fixed charge densities for the salt electrolytes used were found to be in the order LiCl > NH4Cl > KCl > NaCl for the tungstate membrane; while in case of the carbonate membrane, the order is KCl > NaCl > LiCl. The membranes are found to be negatively charged i.e. cation-selective and the selectivity increases with dilution.The physico-chemical characterization of the organic-inorganic hybrids was carried out by using X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy and Scanning electron microscope (SEM) studies.

Composite membranes based on a sulfonated poly(arylene ether sulfone) and proton-conducting hybrid silica particles for high temperature PEMFCs

The organic–inorganic composite membranes are prepared by inserting poly(styrene sulfonate)-grafted silica particles into a polymer matrix of sulfonated poly(arylene ether sulfone) copolymer. The first step consisted in using atom transfer radical polymerization method to prepare surface-modified silica particles grafted with sodium 4-styrenesulfonate, referred to as PSS-g-SiO 2. Ion exchange capacities up to 2.4 meq/g are obtained for these modified silica particles. In a second step, a sulfonated poly(arylene ether sulfone) copolymer is synthesized via nucleophilic step polymerization of sulfonated 4,4′-dichlorodiphenyl sulfone, 4,4′-dichlorodiphenyl sulfone and phenolphthalin monomers in the presence of potassium carbonate. The copolymer is blended with various amounts of silica particles to form organic–inorganic composite membranes. Esterification reaction is carried out between silica particles and the sulfonated polymer chains by thermal treatment in the presence of sodium hypophosphite, which catalyzed the esterification reaction. The water uptake, proton conductivity, and thermal decomposition temperature of the membranes are measured. All composite membranes show better water uptake and proton conductivity than the unmodified membrane. Moreover, the membranes are tested in a commercial single cell at 80 °C and 120 °C in humidified H 2/air under different relative humidity conditions. The composite membrane containing 10%(w/w) of PSS-g-SiO 2 particles, which have ester bonds between polymer chains and silica particles, showed the best performance of 690 mA cm −2 at 0.6 V, 120 °C and 30 %RH, even higher than the commercial Nafion ® 112 membrane.

Proton Exchange Membrane Based on Sulfonated Polyimide for Fuel Cells: State-of-the-Art and Recent Developments

Proton exchange membrane is one of the most important components for proton exchange membrane fuel cells (PEMFCs). The preparation of proton exchange membranes based on sulfonated polyimide (SPI) for PEMFCs in recent years was reviewed, and methods of improving the water stability and proton conductivity of such membranes were highlighted. It was suggested that preparation of novel SPI membranes or organic-inorganic composite SPI membranes should be a reasonable approach to strengthen their combination property.

Novel ABPBI/POSS Composite Membranes for High Temperature PEMFC Applications

Novel organic-inorganic composite membranes involving poly(2,5-benzimidazole) (ABPBI) and polyhedral oligomeric silsesquioxane (POSS) were prepared via in-situ synthesis followed by phosphoric acid doping. The formation of composites was characterized by SEM, XRD and FTIR. The results of water uptake showed that POSS cores emerged extraordinary water absorbability. When doping in phosphoric acid solution, phosphoric acid absorption in composites was dominated by functional groups linked to POSS cores. The excellent proton conductivities i.e. above 0.1S/cm at 100~160oC achieved from anhydrous ABPBI/OA-POSS composite membranes with 241wt.% of phosphoric acid absorption, make them very good candidates as the membranes for high temperature polymer electrolyte membrane fuel cell (PEMFC) applications.

Structural study on inorganic/organic hybrid composite membranes

New composite materials consisting of phosphosilicate (P2O5-SiO2), phosphotungstic acid (PWA), 3-mercaptopropyltrimethoxysilane (MPTS) and glutaraldehyde (GL) were prepared, and a high proton conductivity of 10−2 S cm−1 was observed at room temperature. By incorporating 3-mercaptopropyltrimethoxysilane (MPTS) and glutaraldehyde (GL) in to the P2O5-SiO2-PWA inorganic matrix, the composites showed high proton conductivity in the range of 10−2–10−1 S cm−1 at 120 °C. The structural formation was confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and morphological analysis. The thermal properties were investigated by thermogravimetry (TG) and differential thermal analysis (DTA). A new inorganic–organic composite membrane was successfully prepared by a sol–gel process through hydrolysis and condensation of MPTS and tetraethoxysilane (TEOS). These P2O5-SiO2-PWA-MPTS, P2O5-SiO2-PWA-GL and P2O5-SiO2-PWA-MPTS-GL hybrid composite membranes showed high proton conductivities as a function of temperature. Moreover, they were thermally stable in air up to 250 and 300 °C due to the presence of a tolerant inorganic SiO2 framework in the matrix.

Synthesis and characterization of anhydrous proton conducting inorganic–organic composite membranes for medium temperature proton exchange membrane fuel cells (PEMFCs)

Abstract We report on anhydrous proton conducting inorganic–organic composite membranes synthesized from tetraethoxysilane/poly(-dimethylsiloxane)/trimethylphosphate and 1-ethyl-3 methylimidazolium-bis (trifluoromethanesulfonyl) imide ionic liquid as sol–gel precursors. The Fourier transform infrared spectroscopy, 31P, 1H, and 13C Nuclear magnetic resonance, thermo gravimetric and differential thermal analysis measurements confirmed that the prepared hybrid membranes possess good chemical stability and are thermally stable up to 350 °C. Conductivity of all the fabricated hybrid membranes was measured under anhydrous conditions within the temperature range −20–150 °C, and a value of 4.87 × 10−3 S/cm at 150 °C was achieved for 40 wt% [EMI][TFSI] ionic liquid doped 72TEOS–18PDMS–10PO (OCH3)3 (mol %) hybrid membrane. For 40 wt% ionic liquid doped composite membrane, the measured hydrogen permeability value at 150 °C was 4 × 10−12 mol/cm s Pa.

Proton conducting organic–inorganic composite membranes under anhydrous conditions synthesized from tetraethoxysilane/methyltriethoxysilane/trimethyl phosphate and 1-butyl-3 methylimidazolium tetrafluoroborate

Anhydrous proton conducting organic–inorganic hybrid membranes were fabricated by sol–gel process with tetraethoxysilane/methyltriethoxysilane/trimethyl phosphate and 1-butyl-3 methylimidazolium tetrafluoroborate (BMIMBF 4) ionic liquid as precursors. Chemical stability of these hybrid membranes was investigated by Fourier transform infrared spectroscopy and 31P, 1H, and 13C magic angle spinning nuclear magnetic resonance measurements. Thermogravimetric analysis and differential thermal analysis measurements confirmed that the hybrid membranes were thermally stable up to 280 °C. The effect of ionic liquid addition on the microstructure of the hybrid membranes was examined by Scanning electron microscopy and Energy dispersive X-ray analysis micrographs and no phase separation was observed at the surfaces of the composite membranes and also homogeneous distribution of all the elements was confirmed. For all the prepared composite membranes the conductivities were measured within the temperature range (− 30)–150 °C, and a maximum conductivity of 6.74 × 10 − 3 S/cm at 150 °C was achieved for 40 wt.% ionic liquid based hybrid membrane, under non-humidified conditions. The hydrogen permeability values were decreased with the temperature increment from 20 °C to 150 °C and the measured H 2 permeability value for 40 wt.% ionic liquid based hybrid membrane was 0.5 × 10 − 12 mol/cm s Pa at 150 °C. For 40 wt.% [BMIMBF 4] doped hybrid membrane, membrane electrode assemblies were prepared and a maximum power density value of 2 mW/cm 2 at 4.73 mA/cm 2 as well as a current density of 7.4 mA/cm 2 was obtained at 150 °C under non-humidified conditions when utilized in a H 2/O 2 fuel cell.

Anhydrous Proton Conducting Inorganic–Organic Composite Membranes Based on Tetraethoxysilane/ Ethyl-Triethoxysilane/Trimethylphosphate and 1-Butyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide

In this paper, we report on inorganic–organic composite membranes with anhydrous proton conduction prepared by the sol–gel process with tetraethoxysilane/ethyl-triethoxysilane/trimethylphosphate and 1-butyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide ([BMI][BTSI]) ionic liquid as precursors. The Fourier transform IR spectroscopy, , , and NMR, and thermogravimetric and differential thermal analysis measurements confirmed that the membranes possess good chemical stability and are thermally stable up to . Thermal stability was considerably enhanced by the presence of the inorganic framework and the stability of [BTSI] anion. The conductivity of all the fabricated membranes was measured from −30 to , and a high conductivity of was measured for the 40 wt % [BMI][BTSI] ionic liquid doped membrane at under anhydrous conditions. The hydrogen permeability was decreased from to for the 40 wt % [BMI][BTSI] ionic liquid doped hybrid membrane during temperature increment from 20 to . For 40 wt % ionic liquid doped hybrid membrane, membrane electrode assemblies were fabricated, and a maximum power density value of at as well as a current density of were achieved at under nonhumidified conditions.

Direct synthesis of sulfonated mesoporous silica as inorganic fillers of proton-conducting organic–inorganic composite membranes

The mesoporous silica sphere grafted with organic sulfonic acid has been synthesized by a condensation reaction of 1,3-propane sultone and 3-mercaptopropyltrimethoxy silane, followed by hydrothermal reaction with tetramethoxysilane. Proton-conducting organic–inorganic composite membranes were cast together with Nafion ® using these functionalized mesoporous silicas as inorganic fillers. The composite membrane showed increased water uptake and higher ionic conductivity relative to recast Nafion membrane under low relative humidity condition. This led to enhanced performance of proton exchange membrane fuel cell employing the composite membrane containing the sulfonated mesoporous silica under the low humidity condition without external humidification of reactant gas. The current density at 0.5 V of the membrane–electrode assembly (MEA) fabricated with composite membrane containing the sulfonated mesoporous silica was ca. 3.3 times higher than that of the MEA fabricated with recast Nafion membrane.

New sulfonic acid moiety grafted on montmorillonite as filler of organic–inorganic composite membrane for non-humidified proton-exchange membrane fuel cells

A new organic sulfonic acid moiety is grafted on the surface of montmorillonite (MMT) by a condensation reaction of the surface hydroxyl group of MMT with the thiol group of 3-mercaptopropyltrimethoxy silane (3-MPTMS), and simultaneously attaching sulfonic acid group by a ring opening reaction of 1,3-propane sultone. The new method produces MMT functionalized with sulfonic acid of a longer chain length in a simple one-step reaction and shows higher ion-exchange capacity and thermal stability than MMT grafted by a two-step method of 3-MPTMS condensation followed by oxidation with H 2O 2. Using these functionalized MMTs as inorganic fillers, organic–inorganic composite, proton-conducting membranes are cast together with Nafion ®. The composite membrane with MMT grafted with the long-chain sulfonic acid shows increased water uptake, while maintaining comparable ionic conductivity relative to a pristine Nafion membrane. This leads to much enhanced performance of a proton-exchange membrane fuel cell without external humidification of reactant gases. For instance, the current density at 0.5 V of the membrane–electrode assembly (MEA) fabricated with a composite membrane containing MMT with the long-chain organic sulfonic acid is about twice that of a MEA fabricated with a composite membrane containing MMT with short-chain organic sulfonic acids and about three times higher than that with pristine Nafion 212.

Pervaporation characteristics of pore-filling PDMS/PMHS membranes for recovery of ethylacetate from aqueous solution

Hydrophobic organic–inorganic composite membranes with cross-linked poly(dimethyl siloxane)–poly(methyl hydrogen siloxane) (PDMS/PMHS) were prepared on a porous alumina tubular support. The PDMS/PMHS polymer penetrated into and plugged the pores of the γ-alumina support. The membrane had an approximately 3.5-μm-thick polymer/alumina composite layer. The alumina matrix inhibited the swelling of the PDMS/PMHS membrane. The pervaporation separation of an ethylacetate/water mixture with low percentages of ethylacetate was carried out with these composite membranes. The effect of the thermal treatment of the PDMS/PMHS membrane on the existence of silanol and methyl groups, and the flux and separation factor were investigated. The flux and separation factor were varied depending on the temperature of thermal treatment of the PDMS/PMHS membranes.

Development of a sulfated Y-doped nonstoichiometric zirconia/polysulfone composite membrane for treatment of wastewater containing oil

Polysulfone (PSF) is a kind of popular membrane material for treatment of wastewater containing oil, for it is easily fabricated into ultrafiltration membrane or composite membrane. When treated with wastewater, it has a tendency to be contaminated for its hydrophobicity. In order to enhance the hydrophilic and anti-fouling property of membrane, we added sulfated Y-doped nonstoichiometric zirconia (SO 4 2−/ZrO 2–Y 2O 3; SZY particles) to polysulfone and prepared a novel organic–inorganic composite membrane (SZY/PSF) by a sol–gel process. The optimum preparation conditions of composite membranes were: the ratio of solid (polysulfone and SZY particles), solvent and porogen (polyethylene glycol 400) was 1(g):5(mL):0.8(mL); the mass ratio of SZY particles to polysulfone was 15%; the evaporating time was 10 s and the coagulation bath temperature was 20 °C; intermittent ultrasound was on during the preparation process. Composite membranes were characterized by test of tensile strength, contact angel, porosity and pore diameter and scanning electron microscope (SEM). The results show that composite membrane is difficult to be compacted and approaches twice tensile strength of pure polysulfone membrane; contact angel reduces from 78.1° to 36.6°. SEM micrographs indicate that composite membrane owning the asymmetry structure has two layers of compact layer and porous layer with SZY particles uniformly dispersed in PSF. Wastewater containing oil (80 mg/L) was used to investigate the separation performance of composite membrane. The results reveal that oil retention is 99.16% and oil concentration in the permeation is 0.67 mg/L, which meet the requirement for discharge (<10 mg/L). It can be concluded that the composite membranes developed in the study are reasonably resistant to fouling and hence the developed PSF membranes are considered feasible in treating wastewater containing oil.

Hybrids perfluorosulfonic acid ionomer and silicon oxide membrane for application in ion-exchange polymer-metal composite actuators

This paper reports a new technique to fabricate an ion-exchange polymer-metal composite (IPMC) actuator. This technique is based on a hybrid organic-inorganic composite membrane. In the fabrication course, silica oxide particles, prepared from hydrolysis of tetraethyl orthosilicate in situ with sol-gel reaction, co-crystallize with perfluorosulfonate acid (PFSA) ionomer. Attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) analyses demonstrate that a highly water-saving hybrid membrane is formed. Measurements of mechanical properties reveal that elastic modulus and hardness of the hybrid membrane are about 2 times compared to a commercial PFSA membrane. Scanning electron microscopy (SEM) results show that the hybrid membrane has a high porosity. Inside the membrane pores, there exists a great quantity of micro scale channels in the range of 100–300 nm. After fabrication of IPMC actuator, an electric current sensor, a force sensor, and a high speed camera are assembled and used to evaluate IPMC performance. It is shown that, compared to an IPMC actuator made from a commercial membrane, the electromechanical performance of the new actuator increases 6–8 times; when it is actuated in air, its stable non-water working time is prolonged for 6–7 times.

Novel organic–inorganic composite polymer-electrolyte membranes for DMFCs

Organic–inorganic composite membranes comprising Nafion with inorganic materials such as silica, mesoporous zirconium phosphate (MZP) and mesoporous titanium phosphate (MTP) are fabricated and evaluated as proton-exchange-membrane electrolytes for direct methanol fuel cells (DMFCs). For Nafion–silica composite membrane, silica is impregnated into Nafion matrix as a sol by a novel water hydrolysis process precluding the external use of an acid. Instead, the acidic nature of Nafion facilitates in situ polymerization reaction with Nafion leading to a uniform composite membrane. The rapid hydrolysis and polymerization reaction while preparing zirconia and titania sols leads to uncontrolled thickness and volume reduction in the composite membranes, and hence is not conducive for casting membranes. Nafion–MZP and Nafion–MTP composite membranes are prepared by mixing pre-formed porous MZP and MTP with Nafion matrix. MZP and MTP are synthesised by co-assembly of a tri-block co-polymer, namely pluronic-F127, as a structure-directing agent, and a mixture of zirconium butoxide/titanium isopropoxide and phosphorous trichloride as inorganic precursors. Methanol release kinetics is studied by volume-localized NMR spectroscopy (employing “point resolved spectroscopy”, PRESS), the results clearly demonstrating that the incorporation of inorganic fillers in Nafion retards the methanol release kinetics under osmotic drag. Appreciable proton conductivity with reduced methanol permeability across the composite membranes leads to improved performance of DMFCs in relation to commercially available Nafion-117 membrane.

PDMS–silica composite membranes with silane coupling for propylene separation

Polydimethylsiloxane (PDMS) coated membranes on a polysulfone (PSf) support were fabricated for propylene recovery from off-gas stream. PDMS coated membrane, however, showed trade-off trends that permeability and selectivity are inversely proportional to each other. Addition of silica nanoparticles of 12–400 nm size into PDMS matrix enhanced both separation factor and propylene permeance from 5.2 to 7.3 from 31 to 36 GPU, respectively. Silica nanoparticles in composite membrane tended to agglomerate with each other. Coupling of silica nanoparticles with a silane coupling agent modified the silica surface to enhance the compatibility with PDMS. Several coupling agents for silica nanoparticles in the PDMS/organic solvent system were tested and mercapto silane showed the best characteristics as a coupling agent in terms of hydrophobicity and thermal stability. Successful coupling was confirmed by FT-IR, and better dispersion of coupled silica nanoparticles in PDMS matrix was attained. Composite membrane with coupled silica nanoparticles still enhanced separation factor up to 8.5 and propylene permeance up to 42 GPU. Effects of size and amount of the silica nanoparticles were examined by comparing fumed silica and sol–gel silica. Fumed silica enhanced the sorption of propylene into membrane matrix to increase the separation factor maintaining the propylene permeance. Sol–gel silica disrupted chain packing to increase the propylene permeance maintaining the selectivity. Increase of silica content enhanced the separation factor as well as propylene permeance. However, excessive silica loading in PDMS solution caused problems in coating process, and optimum silica nanoparticle content was 15 wt%. This work showed the novelty in preparation of organic–inorganic composite membranes with enhanced permeance and selectivity by properly coupling the silica particles before loading.

Preparation and characterization of PVDF/TiO 2 organic–inorganic composite membranes for fouling resistance improvement

In this study, a polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane was modified by dispersing nano-sized titanium(IV) oxide (TiO 2) particles in a PVDF solution. PVDF flat-sheet membranes were fabricated by a phase inversion method. Nonwoven fabric and PET film were used as the support layer. This study investigates the effect of TiO 2 nanoparticles, type of coagulants, and support layers on membrane permeability. The experimental result indicates that the membrane surface can be modified by adding TiO 2 nanoparticles, coagulant solvent compositions, and support materials. PVDF membrane fouling was reduced by changing the membrane surface from hydrophobic to hydrophilic after TiO 2 addition. PVDF membranes immersed in pure water coagulation bath solution revealed typical large finger-like structures; however, when water/isopropanol mixtures were used as the coagulant solvent, PVDF membranes exhibited sponge-like structures instead of finger-like structures. By using the PET film (instead of nonwoven fabric) as the support layer, excessive penetration of the cast solution into the support layer could be prevented. However, a dense PET film obstructed the exchange of polymer solution and coagulation bath solution and therefore small pores were formed due to a slow membrane formation process.

Proton-conducting composite membranes from graft copolymer electrolytes and phosphotungstic acid for fuel cells

New organic–inorganic composite membranes based on poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(styrene sulfonic acid) [P(VDF-co-CTFE)-g-PSSA] with embedded phosphotungstic acid (PWA) were prepared. Fourier transform infrared spectra indicated the existence of a specific interaction between P(VDF-co-CTFE)-g-PSSA graft copolymer and PWA particles. PWA nanoparticles were well confined in the polymeric matrix up to 20 wt.%, above which they started to be extracted from the matrix, as revealed by scanning electron microscope analysis. Accordingly, Young’s modulus of membranes also increased with PWA concentration up to 20 wt.%, above which it continuously decreased. Upon incorporation of PWA nanoparticles, the proton conductivity of composite membranes slightly decreased from 0.042 to 0.035 S/cm at room temperature up to 20 wt.%, presumably due to strong interaction between the sulfonic acids of graft copolymer and PWA nanoparticles. The characterization by thermal gravimetric analysis demonstrated the enhancement of thermal stabilities of the composite membranes with increasing concentration of PWA.

Preparation and characterization of novel Ce-doped nonstoichiometric nanosilica/polysulfone composite membranes

Polysulfone (PSF) is a kind of membrane material with better performance and broadly applied in water purification, biochemistry separation, Chinese traditional herb drugs extraction and concentration, etc. But PSF membrane has a tendency to be contaminated for its hydrophobicity, which can result in declining of flux and life of the membrane. To enhance the capability of PSF membrane, such as tensile strength, hydrophilic property, anti-fouling ability, novel organic–inorganic composite membranes were prepared by a process of adding modified nanosilica with higher activity and hydrophilic property to the porous matrix of PSF. Ce-doped nonstoichiometric nanosilica (modified nanosilica) was synthesized by doping the rare earth Ce element. Composite membranes were prepared by sol–gel process and characterized by test of tensile strength, contact angel, porosity, infrared spectroscope (IR), environment scanning electron microscope (ESEM) and performance for oil–water separation. The results show that tensile strength is improved to a large extent and contact angel reduces from 78.6° to 41.7°; porosity reaches 75%. IR spectrum of the composite membrane indicates that the cerium element has entered into the framework of nanosilica. ESEM micrographs indicate that the composite membrane owning the asymmetry structure has two layers of compact layer and porous layer and that modified nanosilica is uniformly dispersed in PSF. The flux in treatment of wastewater containing oil is greatly increased, so it indicates that the anti-fouling ability is significantly enhanced and treatment of wastewater containing oil using the composite membrane developed is feasible and desirable.