Hybrid Ultrafiltration Membranes Research Articles

Development of Hybrid Ultrafiltration Membranes with Improved Water Separation Properties Using Modified Superhydrophilic Metal-Organic Framework Nanoparticles.

Metal-organic frameworks (MOFs) are being intensively explored as filler materials for polymeric membranes primarily due to their high polymer affinity, large pore volumes, and alterable pore functionalities, but the development of MOF-based ultrafiltration (UF) membranes for water treatment lags behind. Herein, poly(sulfobetaine methacrylate) (PSBMA)-functionalized MOF UiO-66-PSBMA was developed, and incorporated into polysulfone (PSf) casting solution to fabricate novel hybrid UF membranes via phase-inversion method. The resultant UiO-66-PSBMA/PSf membrane exhibited significantly improved water flux (up to 602 L m-2 h-1), which was 2.5 times that of the pristine PSf membrane (240 L m-2 h-1) and 2 times that of UiO-66-NH2/PSf membrane (294 L m-2 h-1), whereas the rejection of UiO-66-PSBMA/PSf membrane was still maintained at a high level. Moreover, UiO-66-PSBMA/PSf membrane exhibited improved antifouling performance. The improvement of membrane performances could be attributed to the well-tailored properties of UiO-66-PSBMA. On one hand, the excellent dispersion and compatibility of UiO-66-PSBMA ensured the formation of a uniform structure with few defects. On the other hand, the superhydrophilicity of UiO-66-PSBMA could accelerate the exchange rate between solvent and nonsolvent, resulting in a more hydrophilic surface and a more porous structure. Besides, UiO-66-PSBMA nanoparticles in the thin layer provided additional flow paths for water permeation through their hydrophilic porous structure as well as the tiny interspace between PSf matrix. This study indicates the great application potential of UiO-66-PSBMA in fabricating hybrid UF membranes and provides a useful guideline to integrate other modified hydrophilic MOFs to design UF membranes for water treatment.

Versatile polyvinylidene fluoride hybrid ultrafiltration membranes with superior antifouling, antibacterial and self-cleaning properties for water treatment

Novel ultrafiltration membranes with both superior antibacterial and self-cleaning properties were fabricated. By using a non-solvent induced phase separation method (NIPS), N-halamine epoxide and siloxane were grafted onto the multi-walled carbon nanotubes (N-Si-MWNTs) to fabricate polyvinylidene fluoride (PVDF) hybrid membranes. The membrane morphology was observed under a field emission scanning electron microscopy. The results demonstrated that the PVDF hybrid membranes had an asymmetrical structure, and their hydraulic permeability was evidently enhanced with the addition of modified MWNTs. When compared with the primitive PVDF membrane, the hybrid membranes presented improved surface hydrophilicity. After three ultrafiltration–regeneration cycles with bovine serum albumin as model biofoulant and pure water as detergent, the PVDF hybrid membranes exhibited a high flux recovery ratio (FRR). Furthermore, when compared with other membranes, the membrane containing N-Si-MWNTs displayed the highest FRR value of above 96.5% after the entire fouling and cleaning experiment. The fabricated PVDF/N-Si-MWNTs hybrid membranes had excellent antibacterial efficacy, presenting maximum antibacterial efficacy of 98.0% and 95.6% against Staphylococcus aureus and Escherichia coli, respectively. Thus, the PVDF/N-Si-MWNTs membranes fabricated in this study are environment-friendly with both benign antibacterial and self-cleaning properties.

Preparation and characterization of novel polysulphone hybrid ultrafiltration membranes blended with N-doped GO/TiO2 nanocomposites

N-doped graphene oxide (NRG), one of the graphene oxide derivatives, has been widely incorporated with TiO2 nanoparticles because they increase interfacial contact between graphene and TiO2 nanoparticles. However, introduction of NRG/TiO2 (NRGT) nanocomposites into the membrane matrix to improve the hydrophilicity, permeability, and antifouling properties of ultrafiltration membranes has not been studied. In this work, NRGT nanocomposite was synthesized by sol–gel reaction using NRG nanosheet suspension and tetrabutyl titanate. The synthesized NRGT nanocomposites were used as fillers at different ratios to fabricate novel hybrid ultrafiltration membranes through non-solvent-induced phase-separation method. SEM, FTIR, AFM, TGA, contact-angle experiments, and filtration experiments using water and BSA were performed to characterize the surface morphology, thermal stability, hydrophilicity, structure, pore size distribution, water permeability, and antifouling performance of the membranes. The membranes were found to have an asymmetric structure with high dispersibility of NRGT nanocomposites. They showed high hydrophilicity, permeability, and resistance to fouling with BSA solution, depending on the amount of NRGT nanocomposites blended.

Novel organic-inorganic hybrid polyvinylidene fluoride ultrafiltration membranes with antifouling and antibacterial properties by embedding N-halamine functionalized silica nanospheres

Abstract Novel polyvinylidene fluoride (PVDF) hybrid ultrafiltration membranes with antifouling and antibacterial properties are prepared by embedding N-halamine functionalized silica nanospheres (HFSNs). With the addition of HFSNs, the antifouling properties of PVDF membranes are significantly improved. The results reveal that the highest pure water permeation flux of 559.8 L m−2 bar−1 h−1 is attained when the 0.6 wt% HFSNs is added in the casting solution. The membrane of M-3 with 0.9 wt% HFSNs addition shows the highest sterilization ratios of 97.1% and 97.0% against (escherichia coli) E. coli and (staphylococcus aureus) S. aureus respectively. After 6 times of inhibition-activation cycles, the membrane still remains 72.3% against E.coli.

Optimized permeation and antifouling of PVDF hybrid ultrafiltration membranes: synergistic effect of dispersion and migration for fluorinated graphene oxide

Nanoparticles may have suffered from low modification efficiency in hybrid membranes due to embedding and aggregating in polymer matrix. In order to analyze the modification mechanisms of nanoparticle migration and dispersion on the properties of hybrid membranes, we designed different F/O ratios (RF/O) of fluorinated graphene oxide (FGO, diameter = 1.5 ~ 17.5 μm) by carbon tetrafluoride (CF4) plasma treatment GO for 3, 5, 10, 15, and 20 min and successfully prepared novel PVDF hybrid membranes containing FGO via the phase inversion method. After a prolonged plasma treatment, the RF/O of FGO was enhanced sharply, indicating an increasing compatibility of FGO with the matrix, especially FGO-20 (GO treated for 20 min). FGO contents in the top layer, sublayer, and the whole of membranes were probed by X-ray photoelectron spectroscopy, energy-dispersive spectrometer, and indirect computation, respectively. In the top layer of membranes, FGO contents declined from 13.14 wt% (PVDF/GO) to 4.00 wt% (PVDF/FGO-10) and 1.96 wt% (PVDF/FGO-20) due to the reduced migration ability of FGO. It is worth mentioning that PVDF/FGO-10 membranes exhibited an excellent water flux and flux recovery rate (up to 406.90 L m−2 h−1 and 88.9%), which were improved by 67.3% and 14.6% and 52.5% and 24.0% compared with those of PVDF/GO and PVDF/FGO-20 membranes, respectively, although the dispersion and migration ability of FGO-10 was maintained at a moderate level. It indicated that the migration and dispersion of FGO in membranes could result in dynamic equilibrium, which played a key role in making the best use of nanomaterials to optimize membrane performance.

Antifouling hybrid ultrafiltration membranes with high selectivity fabricated from polysulfone and sulfonic acid functionalized TiO2 nanotubes

In this work, antifouling hybrid ultrafiltration membranes were manufactured using polysulfone (PSf) and sulfonic acid functionalized TiO2 nanotubes (TNTs-SO3H). TNTs-SO3H were first synthesized by performing a coupling reaction between 3-mercaptopropyl trimethoxysilane and hydroxyl groups on TiO2 nanotubes with in situ oxidation using 30wt% H2O2 solution. Hybrid membranes containing TNTs-SO3H up to 5wt% were then prepared from the blend solutions of PSf/TNTs-SO3H via a non-solvent induced phase separation (NIPS) method. The hybrid membranes were characterized using contact angle, Fourier transform infrared spectroscopy, scanning electron microscopy and surface zeta potential studies. The antifouling capability of hybrid membranes with bovine serum albumin and humic acid (HA) as model foulants were investigated in detail. Hybrid membranes exhibited better water permeability and antifouling performance during filtration of foulant solutions. The ultrafiltration of HA solutions of different concentrations was carried out at pH=7 and 1bar feed pressure, with the removal of HA from aqueous solution being controlled through the charged behaviour, porosity and exclusion of HA by hybrid membranes. The maximum removal of HA from 20ppm aqueous solution was achieved using the hybrid membrane MTS-5 containing 5wt% TNTs-SO3H.

Self-cleaning anti-fouling hybrid ultrafiltration membranes via side chain grafting of poly(aryl ether sulfone) and titanium dioxide

We report the fabrication and characterization of a novel organic/inorganic hybrid ultrafiltration membrane with anti-fouling and self-cleaning properties. Nanoscale TiO2 clusters were grafted on the side chains of a poly(aryl ether sulfone) matrix containing trifluoromethyl and carboxyl groups (PES-F-COOH) using a silane coupling agent. Separation efficiency, fouling behavior, and self-cleaning property of the TiO2/PES-F-COOH hybrid ultrafiltration membrane were investigated by dead-end filtration experiments using a polyacrylamide foulant solution. Analysis of the membrane chemistry showed that grafting TiO2 on the side chain of the PES-F-COOH resulted in homogeneous dispersion of TiO2 clusters in the polymer matrix. The hybrid UF membrane exhibited significant self-cleaning efficiency. Specifically, water flux following polyacrylamide fouling was 53% recovered after membrane exposure to UV irradiation, which is attributable to photocatalytic degradation of the organic foulants by TiO2. We further demonstrated the anti-photocatalytic ageing property of the hybrid UF membrane, indicating resistance to decomposition of the membrane polymer matrix by photocatalytic oxidation. Our developed method can serve as a versatile platform for the development of anti-fouling and self-cleaning hybrid membranes or functional materials for a wide range of applications.

Flux improvement, rejection, surface energy and antibacterial properties of synthesized TiO2-Mo.HNTs/PVC nanocomposite ultrafiltration membranes

The present work demonstrates the preparation of modified halloysite loaded with titanium dioxide (TiO2) nanoparticles and its use as a nanofiller in a poly(vinyl chloride) (PVC) hybrid ultrafiltration (UF) membrane for advanced water treatment.

Synthesis and characterization of silver decorated polysulfone/cellulose acetate hybrid ultrafiltration membranes using functionalized TiO2 nanoparticles

Synthesis and characterization of silver decorated polysulfone/cellulose acetate hybrid ultrafiltration membranes using functionalized TiO2 nanoparticles

Electrochemical Deposition of Zinc Oxide on the Surface of Composite Membrane Polysulfone-Graphene-Polystyrene in the Presence of Water Soluble Polymers

The aim of this study consisted in the development of an alternative synthesis procedure for hybrid ultrafiltration membranes for water purification. The membranes were obtained by wet-phase inversion method based on aliquots of polysulfone (PSF) and graphene nanoplatelets modified with poly(styrene) (G-PST). The hybrid materials were modified by electrochemical deposition of zinc oxide (ZnO) on one side of the membranes in the presence of water soluble polymers. Raman, XPS, and TGA analyses were used to characterize the chemical and thermal characteristics of the PST-G. SEM analysis showed the formation of asymmetric porous configuration in all cases and the generation of ZnO with different shapes/structures on the bottom surface of the membrane or inside the porous channels. EDS analysis confirmed the formation of ZnO.

Photocatalytic antifouling PVDF ultrafiltration membranes based on synergy of graphene oxide and TiO2 for water treatment

A novel graphene oxide/TiO2-polyvinylidene fluoride (GO/TiO2-PVDF) hybrid ultrafiltration membrane has been successfully developed via the phase inversion technique by supplementing with GO/TiO2 nanocomposites, in which the synergistic coupling of GO and TiO2 could result in improved photocatalytic activity and endow hybrid membranes with photocatalytic antifouling function. Compared with PVDF membranes supplemented with TiO2 and GO, respectively, the GO/TiO2-PVDF membrane displayed significantly improved photodegradation efficiency (improved about 50–70%) and superior photodegradation kinetics (1.0–1.5 times faster) toward bovine serum albumin (BSA). Moreover, flux performance and flux recovery ratio of membranes revealed that the GO/TiO2-PVDF membrane could recover high flux after fouling, which thus presented self-cleaning property under UV static irradiation. Besides, the GO/TiO2-PVDF membrane showed a water flux up to 487.8Lm−2h−1, more than 2 times that of the pristine PVDF membrane, while keeping high BSA rejection (92.5%). Therefore, the GO/TiO2-PVDF membrane would have good potential in water treatment due to its high-performance multifunctional characters, i.e. separation, photocatalytic oxidation and self-cleaning, etc.

Manipulating Migration Behavior of Magnetic Graphene Oxide via Magnetic Field Induced Casting and Phase Separation toward High-Performance Hybrid Ultrafiltration Membranes.

Hybrid membranes blended with nanomaterials such as graphene oxide (GO) have great opportunities in water applications due to their multiple functionalities, but they suffer from low modification efficiency of nanomaterials due to the fact that plenty of the nanomaterials are embedded within the polymer matrix during the blending process. Herein, a novel Fe3O4/GO-poly(vinylidene fluoride) (Fe3O4/GO-PVDF) hybrid ultrafiltration membrane was developed via the combination of magnetic field induced casting and a phase inversion technique, during which the Fe3O4/GO nanocomposites could migrate toward the membrane top surface due to magnetic attraction and thereby render the surface highly hydrophilic with robust resistance to fouling. The blended Fe3O4/GO nanocomposites migrated to the membrane surface with the magnetic field induced casting, as verified by X-ray photoelectron spectroscopy, elemental analysis, and energy dispersive X-ray spectroscopy. As a result, the novel membranes exhibited significantly improved hydrophilicity (with a contact angle of 55.0°) and water flux (up to 595.39 L m(-2) h(-1)), which were improved by 26% and 206%, 12% and 49%, 25% and 154%, and 11% and 33% compared with those of pristine PVDF membranes and PVDF hybrid membranes blended with GO, Fe3O4, and Fe3O4/GO without the assistance of magnetic field during membrane casting, respectively. Besides, the novel membranes showed high rejection of bovine serum albumin (>92%) and high flux recovery ratio (up to 86.4%). Therefore, this study presents a novel strategy for developing high-performance hybrid membranes via manipulating the migration of nanomaterials to the membrane surface rather than embedding them in the membrane matrix.

Preparation and characterization of low fouling novel hybrid ultrafiltration membranes based on the blends of GO−TiO2 nanocomposite and polysulfone for humic acid removal

In this work, graphene oxide (GO)−TiO2 nanocomposite was synthesized by in situ sol−gel reaction at pH=2 using GO nanosheets suspension and titanium isopropoxide precursor. The synthesized GO−TiO2 nanocomposite was explored as a filler to fabricate improved antifouling novel hybrid ultrafiltration membranes for removal of humic acid from aqueous solution. Membranes were fabricated from polymer blend solutions containing polysulfone and GO−TiO2 with varied loading amount (0–5wt%) by the non-solvent induced phase separation (NIPS) method. Contact angle, atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and outer surface zeta potential studies were conducted in order to characterise the membranes in terms of roughness, structure, surface properties and charge. The porous hydrophilic hybrid membranes were shown to have an asymmetric structure with improved surface roughness. The water permeability and antifouling capacity of hybrid membranes with 10ppm HA solution were dependent on the loading amount of GO–TiO2. Incorporation of GO–TiO2 nanocomposite was found to improve the antifouling characteristics of the membranes when challenged with HA solutions. Irreversible HA fouling was substantially reduced with increased loading of GO−TiO2 nanocomposite (wt%). The lowest irreversible fouling ratio (3.2%) was obtained for the membrane containing 5wt% nanocomposite (to total wt% of PSf, MG−5). Ultrafiltration of HA solutions of varied concentrations using hybrid membranes was studied at pH=7 and 1bar feed pressure. The removal efficiency of hybrid membranes for HA was controlled by the membrane surface charge concentration, porosity and HA exclusion. The membrane MG−5 had the highest HA removal efficiency for 10ppm HA solution at pH=7.

Enhanced hydrophilicity of a thermo-responsive PVDF/palygorskite-g-PNIPAAM hybrid ultrafiltration membrane via surface segregation induced by temperature

The hydrophilicity of a thermo-responsive PVDF/palygorskite-g-PNIPAAM hybrid ultrafiltration membrane was enhanced via surface segregation induced by coagulation bath temperature (CBT).

Poly(arylene sulfide sulfone) hybrid ultrafiltration membrane with TiO2‐g‐PAA nanoparticles: Preparation and antifouling performance

Poly(arylene sulfide sulfone) (PASS) is a kind of newly developed polymeric membrane material which has excellent mechanical strength, thermal stability, and solvent resistance. And, it would be a potential material for high temperature ultrafiltration and organic solvent filtration. In this article, PASS hybrid ultrafiltration membrane with improved antifouling property was prepared by mixing TiO2 nanoparticles which were grafted with polyacrylic acid (PAA). These membranes were prepared by a phase inversion technique and their separation performance and antifouling property of the prepared membranes were investigated in detail by SEM, FTIR, EDS, contact angle goniometry, filtration experiments of water, and BSA solution. The results shown that the TiO2‐g‐PAA nanoparticles dispersed well in membrane matrix, the hydrophilicity of the membranes prepared within TiO2‐g‐PAA nanoparticles have been improved and these membranes exhibited excellent water flux and antifouling performance in separation than that of the pure PASS membranes and PASS membranes with TiO2 nanoparticles. More specifically, among membrane sample M0, M1.5, and MP1.5, MP1.5 which contained 1.5 wt% TiO2‐g‐PAA exhibited the highest water permeation (190.4 L/m2 h at 100 kPa), flux recovery ratio, and the lowest BSA adsorption amount. POLYM. ENG. SCI., 55:2829–2837, 2015. © 2015 Society of Plastics Engineers

Zwitterionic chitosan–silica–PVA hybrid ultrafiltration membranes for protein separation

Zwitterionic (ZI) membranes are well-known for their high resistance to protein fouling during ultrafiltration (UF). In this work, zwitterionic chitosan (ZICS) was firstly obtained by a Schiff-base formation and a sulfonation reaction. Then a series of zwitterionic organic–inorganic hybrid ultrafiltration membranes were prepared through linking ZICS with poly vinyl alcohol (PVA) using tetraethyl orthosilicate as a bridge, where the density of zwitterionic groups in the membranes was adjusted by varying the dosage of zwitterionic chitosan. The prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and the measurements of water contact angle and zeta-potential of membrane surface. The ultrafiltration performance was examined using the separation of bovine serum albumin (BSA) and lysozyme (LYZ) as a model system. The results show that, zwitterionic chitosan–silica–PVA hybrid membranes can possess desirable porosity, hydrophilicity, permeability, antifouling capacity and selectivity which can be adjusted by the fraction of ZICS in membranes.

Novel polyethersulfone hybrid ultrafiltration membrane prepared with SiO2-g-(PDMAEMA-co-PDMAPS) and its antifouling performances in oil-in-water emulsion application

To avoid the agglomeration of nanoparticles (NPs) in hybrid membranes and alleviate the leakage of NPs during the oily wastewater treatment process, poly(2-(dimethylamino)ethylmethacrylate-co-3-dimethyl(methacryloyloxyethyl)ammoniumpropanesulfonate) (PDMAEMA-co-PDMAPS) grafted silica (SiO2) [SiO2-g-(PDMAEMA-co-PDMAPS)] NPs were prepared by grafting PDMAEMA brushes onto SiO2 NPs surface via the surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (Si-ARGET ATRP). Subsequently, the quaternization of the tertiary amine groups in PDMAEMA and 1,3-propanesultone was performed to get [SiO2-g-(PDMAEMA-co-PDMAPS)] NPs. Then, the organic–inorganic hybrid polyethersulfone (PES) membranes with different ratios of SiO2 NPs (m membranes) and SiO2-g-(PDMAEMA-co-PDMAPS) NPs (M membranes) were fabricated via the non-solvent induced phase separation (NIPS) process. Transmission electron microscopy (TEM) images demonstrated that the modification of SiO2 NPs with PDMAEMA-co-PDMAPS was favorable for their homogeneous dispersion in organic solvents. The results of scanning electron microscopy (SEM) images indicated that the surface porosity and mean pore size of hybrid membranes were increased compared to the neat PES membrane. Furthermore, the M membranes exhibited better hydrophilicity, pure water flux and oil flux than neat PES membrane and m membranes. It was found from filtration results that the total fouling (Rt) and irreversible fouling (Rir) were significantly reduced due to higher hydrophilicity of hybrid membranes. In addition, after oil-in-water emulsion filtration, M membranes exhibited higher water flux recovery ratio (FRR) value than that of m membranes and neat PES membrane.

Development of new hybrid ultrafiltration membranes by entanglement of macromolecular PPSU‐SO3H chains: Preparation, morphologies, mechanical strength, and fouling resistant properties

ABSTRACTThe present work focuses on the preparation of Polyphenylsulfone (PPSU) membranes with enhanced antifouling surfaces through an incorporation of sulfonated Polyphenylsulfone (PPSU‐SO3H), which acts as both, surface modifying agent and macromolecular additive. Initially, Sulfonated polyphenylsulfone (PPSU‐SO3H) was synthesized by using chlosulfonic acid via bulk modification method. The degree of sulfonation (DS, %) of PPSU‐SO3H was calculated by using NMR (nuclear magnetic resonance).The phase inversion technique was used to prepare all asymmetric membranes by allowing the PPSU‐SO3H (different wt %) to entangle with the PPSU membrane matrix. All prepared membranes were characterized by using scanning electron microscope (SEM), X‐ray diffraction analysis (XRD), contact angle analysis (CA), mechanical strength analysis, molecular weight cut off (MWCO), porosity (%), mean pore size, and BSA adsorption studies. The performance efficiency of the membranes was evaluated by using BSA protein as a model foulant in terms of permeability, rejection (SR %), Rm (hydraulic resistance), Rc (cake layer resistance), Rp (pore plugging resistance), Rr (reversible fouling), Rir (irreversible fouling), and FRR (flux recovery ratio). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41986.

Effects of PVDF/SiO2 hybrid ultrafiltration membranes by sol–gel method for the concentration of fennel oil in herbal water extract

PVDF/SiO2 membranes by sol–gel were characterized and ultrafiltration performance of fennel oil in water extract through them was effectively improved.

Recovery of beta-Amylase by Hybrid UF Membranes from the Soy Whey Wastewater

Large-scale manufacturing of soybean proteins results in huge volume of “wastewater” which contains substantial amount of β-amylase, and the recovery of β-amylase has potential high value. In order to evaluate the feasibility and effect of novel hybrid Ultrafiltration (UF) method against the normal method, the pretreated effluent was concentrated by a low molecular weight cut off (MWCO) 3 kDa UF membrane firstly, terminated at Volume Concentration Ratio (VCR) of ca.7. To this UF retentate was then precipitated by adding 1.2M (NH4)2SO4 to remove other proteins. The supernatant obtained following centrifugation was purified through a further higher 30 kDa MWCO UF membrane, which ended at VCR of ca.10. The prepared was purified 4.8 fold, with an enzyme activity concentration ratio of 61, and is associated with 74% combined recovery for the enzyme activity, giving a final specific activity of 14 U/mg (674 U/mL), of which enzyme activity is fully enough for the industrial applications. Preliminary data of this research indicate that this could be an effective method for treating kinds of related protein wastewaters.