Composite Ultrafiltration Membranes Research Articles

Development of composite ultrafiltration membrane from fly ash microspheres and alumina nanofibers for efficient dye removal from aqueous solutions

In this work, a novel type of ultrafiltration ceramic membranes with the support based on fine fly ash microspheres and selective layer based on the alumina nanofibers with an aluminosilicate binder is proposed. The average pore sizes of the support and selective layer are 0.46 μm and 29 nm, respectively. The membrane is characterized by the compressive strength of 96 MPa and water permeability of 207 L m−2 h−1 bar−1. It is shown that the binder provides structural stability of selective layer and adhesion to the support. With increasing the binder content, the water permeability increases, reaches maximum, and then slightly decreases. The developed membranes are used for ultrafiltration of Blue Dextran dyes aqueous solutions with molecular weights of 70 kDa and 500 kDa and concentrations of 50 and 100 mg/L. The dyes rejection varies in the range 97–99 %, while the permeate flux is 100–140 L m−2 h−1 at the transmembrane pressure of 4 bars. The dye retention occurs via adsorption at the initial stage, which leads to the narrowing of pore size. Further, the dye filtration proceeds mainly due to size effects. The proposed membranes can be employed for dye removal from wastewater, and also allow chemical modification by carbon coating to be employed in electrochemically assisted ultrafiltration. The developed methodology promotes the recycling of thermal energy waste and introduces novel approaches to combine waste and synthesized raw materials in the production of low-cost ceramic membranes.

Surface reconstruction of sulfonated polysulfone ultrafiltration membrane with cellulose nanocrystals for enhancing anti-fouling performance

The fouling issues of ultrafiltration membranes is one of limitations for their long-term effectiveness. Here, we developed an effective and environmentally friendly approach for constructing anti-fouling ultrafiltration membrane, achieved by the surface modification of sulfonated polysulfone (SPSF) ultrafiltration membrane with cellulose nanocrystals (CNCs). The composite ultrafiltration membrane was obtained by only filtering CNC suspension through SPSF ultrafiltration membrane, and showed good hydrophilicity that its water contact angle is only 53° which is much lower than that of SPSF ultrafiltration membrane (74°). Its retention rate for the pollutants with particle size greater than 10 nm is close to 100 %. Its water flux is almost twice that of SPSF ultrafiltration membrane under the sewage condition. After three cycles of filtering severe sewage, its flux recovery rate is still 95 %, far higher than that of SPSF ultrafiltration membrane (60 %). Therefore, the surface modification strategy of SPSF ultrafiltration membrane with CNCs is effective and green for improving the anti-fouling properties of ultrafiltration membranes, which is a valuable reference for enhancing the anti-fouling performance of ultrafiltration membranes from various materials. The as-prepared CNCs/SPSF ultrafiltration membrane has a promising application in the purification of wastewater containing hydrophobic particles.

Dual synergies of functionalized hydrophilic MOFs based poly (aryl ether ketone sulfone) ultrafiltration membranes: Electrostatic action and pore size screening

In this paper, amino monomer (4Am-PH) and the sulfonated poly (arylene ether ketone sulfone) involving amino groups (Am-SPAEKS) were successfully prepared by diazotization reaction and direct polycondensation, respectively. The polyethyleneimine-modified UiO-66-NH2 (P-MOFs) were prepared as fillers. Composite membranes were fabricated by incorporating different contents of P-MOFs into Am-SPAEKS polymer matrix using non-solvent-induced phase separation. The morphology, chemical structure and properties of the polymers, fillers and composite membranes were proved by FT-IR, 1H NMR, FE-SEM, XPS and etc. The final experimental results showed that the introduction of hydrophilic fillers, P-MOFs, substantially improved the hydrophilicity, water flux and antifouling capabilities of the membranes. The water contact angle decreased from 78.5° to 56.4°. The flux of water from a pure membrane was 333.68 L/m2 h. When the content of P-MOFs was 0.1 %, the water flux could attain to 830.23 L/m2 h, the retention rate of bovine serum albumin (BSA) solution could attain to 98.6 % and the flux recovery rate (FRR) values of the composite membrane remained high (86.1 %) for BSA solution. In addition, after three cycles, the pure water flux of the composite membrane could still attain 595.49 L/m2 h. The results demonstrated that P-MOFs have significant potential for utilization in the preparation of composite ultrafiltration membranes and provided an effective idea for the modification and design of other hydrophilic MOFs applied in the study area of ultrafiltration membranes.

Surface Grafting of Magnetic Carbon Nanotubes and Their Vertical Alignment in PVDF Asymmetric Ultrafiltration Membranes for Fast Nanochannel Construction

The application of carbon nanotubes (CNTs) in water treatment membranes can increase the permeability and selectivity of the membranes. However, traditional CNTs are usually affected by van der Waals forces, which makes them prone to agglomerate in polymer membranes, and their non-directional arrangement in the membranes limits their transport efficiency as water channels in the membranes. In this paper, a reversible addition-fragmentation chain transfer (RAFT) polymerization method was used to synthesize propargyl methacrylate - random copolymerization - poly (ethylene glycol) methacrylate - block - polymethyl methacrylate [P(PgMA-r-PEGMA) -b-PMMA]. The P(PgMA-r-PEGMA)-b-PMMA grafting rate was 60.4% on the surface of magnetic sulfhydryl functionalized carbon nanotubes (mCNTs-SH) by click-reaction grafting. Poly (vinylidene fluoride) (PVDF)/CNTs composite ultrafiltration membranes were prepared using vapor-induced phase separation (VIPS) combined with magnetic field arraying. When the mCNTs-g-P(PgMA-r-PEGMA)-b-PMMA were vertically aligned in the PVDF membrane through a magnetic field, the effective construction of the vertical nanochannels was realized, and an increased purified water flux from 25.6 LMH to 35.8 LMH, with the composite ultrafiltration membranes was obtained. In addition, the membranes also showed excellent hydrophilicity, mechanical properties, and polyethylene glycol 1200 (PEG1200) rejection. The water contact angle was reduced from 105° to 79°, the rejection of PEG1200 was increased from 44% to 91% of the 0.5 g/L PEG aqueous solutions, and excellent mechanical properties (tensile strengthes up to 9.3 MPa) were achieved. By designing the interface structure of the CNTs and studying the orientation of the CNTs in PVDF membranes, this work provides a new research idea for the field of water treatment ultrafiltration membranes.

Combinational strategy of chemical graft and layer-by-layer assembly of novel nanocomposite membranes fabrication for heavy metal ion capture

Heavy metal ions (HMI), a non-degradable toxic substance, has raised widespread concerns in water purification. Membrane separation is a considerable and promising technology for removing HMIs from water, due to its environmentally friendly, clean and highly effective. This study reported a functional composite ultrafiltration membrane prepared from natural biomolecules ε-Poly-L-lysine hydrochloride (PLL), sodium lingo sulfonate (SLS) or sodium alginate (SA) based on the combination strategy of chemical graft and layer-by-layer assembly. The fabricated membrane exhibited a high pure water flux (2957 L·m−2·h−1), high capture efficiency for Cu2+ (99.1 %) and Pb2+ (98.9 %). Notably, the layer-by-layer assembly strategy provides abundant groups for HMI binding, ensuring the high capture efficiency. The fabricated membrane demonstrated a low flux decline (9 %), along with a high flux recovery ratio (99.2 %). Moreover, it exhibited exceptional stability and reusability across a wide pH range (pH 5–9), meanwhile maintaining a capture efficiency of approximately 99 % under near-neutral condition after undergoing 5 cycle experiments for both Cu2+ and Pb2+. Our work builds a straightforward approach for UF membrane fabricating with excellent HMI capture capacity, displaying the potential application in HMI waste water purification.

High-performance antibacterial tight ultrafiltration membrane constructed by co-deposition of dopamine and tobramycin for sustainable high-salinity textile wastewater management

High-salinity textile wastewater is a pressing environmental concern, urgently requiring the appropriate treatment. Sustainable management of high-salinity textile wastewater via fractionation of the existing dyes and inorganic salts (NaCl) using selective separation membranes is a key approach to address this detrimental concern. Herein, tight composite ultrafiltration membranes with impressive antibacterial function were constructed using one-step co-deposition of dopamine and tobramycin on the porous substrate to fractionate the dyes and NaCl. Triggered by ammonia persulfate, the polydopamine/tobramycin coating layer imparts the fabricated composite ultrafiltration membranes with tight surface structure and narrow pore size distribution, enabling effective dyes/salts fractionation. Specifically, the tight composite ultrafiltration membrane with a molecular weight cutoff of 3692 Da experienced a > 98.0 % rejection against various reactive dyes (molecular weight: <1000 Da) with nearly complete salt transmission (<0.8 % NaCl rejection), demonstrating an effective fractionation of dyes and salts. Additionally, the incorporated tobramycin as a broad-spectrum antibiotic endowed the tight composite ultrafiltration membrane with a sufficient inhibition efficiency (i.e., 100 %) against E. coli bacteria in a short-time contact (i.e., 3 min). Thereby, the tight composite ultrafiltration membrane constructed by fast co-deposition of dopamine and tobramycin established an unparalleled platform technology for sustainable resource recovery (dyes or salts) from high-salinity textile wastewater.

Carbon Nanosphere Composite Ultrafiltration Membranes with Anti-Biofouling Properties and More Porous Structures for Wastewater Treatment Using MBRs

Carbon Nanosphere Composite Ultrafiltration Membranes with Anti-Biofouling Properties and More Porous Structures for Wastewater Treatment Using MBRs

Preparation and characterization of high flux cellulose acetate/hydroxyapatite composite ultrafiltration membranes for water treatment

In this study, we prepared cellulose acetate/hydroxyapatite (CA/HA) composite ultrafiltration membranes for water treatment. The organic-inorganic composite ultrafiltration membranes were prepared by doping different contents of HA nanoparticles into the CA by phase inversion method. The structure and morphology of the HA nanoparticles and membranes were characterized by X-ray diffraction, Fourier infrared spectroscopy and Scanning electron microscopy. Thermogravimetric analysis was used to describe thermal characteristics. The contact angle value and wettability test were used to determine the hydrophilicity of the polymer membrane. In addition, fluxes and rejection rates were tested at different pollutant concentrations and different pH values. The pore size and porosity gradually increased and the hydrophilicity and thermal stability of membrane were improved with the deposited HA content. With the addition of 5 wt% HA, the tensile strength of the membrane reached a maximum value of 2.80 MPa. The fluxes of pure water, CR, MB and BSA were 152.23, 111.25, 125.69 and 87.47 L/(m2·h), while the rejection rates of CR, MB and BSA were 99.99 %, 92.91 % and 99.99 %, respectively. In addition, the rejection decreased with increasing dye concentration and showed higher rejection under alkaline conditions. On the whole, the produced CA/HA composite membranes exhibited significantly higher permeability and rejection rates, offering them a lot of potential for water treatment applications.

Fabrication of high permeability and antifouling composite membrane loaded with Fe3O4 nanoparticles via a magnetic field induced phase separation

Membrane fouling increases operational expenses and limits the application of ultrafiltration technology in water treatment. To mitigate the membrane fouling, this study incorporated Fe3O4 nanoparticles (NPs) into the polyethersulfone (PES) membrane casting solution, and developed a non-solvent induced phase separation (NIPS) method assisted by a magnetic field (MGF) to fabricate the Fe3O4 NPs composite ultrafiltration membrane. The combination of MGF and Fe3O4 NPs synergistically enhanced the permeability and separation performance of the composite membrane. The performance of the membrane was determined by its structure. With the involvement of MGF, Fe3O4 NPs were enriched on the surface layer of the membrane, resulting in enhanced hydrophilicity of the composite membrane. The membrane permeability increased to 913.39 LMH·bar−1, and the rejection performance rose to 93 % due to the formation of tiny pores on the membrane surface that facilitated solvent diffusion during phase separation, thereby counteracting the adverse effects of heightened viscosity in the casting solution. Moreover, the Fe3O4 NPs composite membrane fabricated with MGF induction exhibited significantly enhanced antifouling capability in multi-cycle fouling tests, resulting in a 27.5 % increase in specific flux compared to the pure PES membrane. Additionally, the preparation procedures for the matrix membrane were optimized to include 15 wt% PES, 3 wt% PVP, and a pre-treatment time of 30 s. These findings have significant implications for advancing the widespread application of membrane technology.

Investigating the effects of polypropylene-TiO2 loading on the performance of polysulfone/polyetherimide ultrafiltration membranes for azo dye removal: Experimental and molecular dynamics simulation

This research paper delves into developing and analyzing advanced composite ultrafiltration (UF) membranes specifically tailored for water treatment and dye removal applications. The composite UF membranes were designed using a combination of polysulfone (PSF), polyetherimide (PEI), and polypropylene-80 wt% TiO2 (PPTiO2) to create the active layer, while a flat polyamide (PA) serves as the support material and is prepared via the spin/spray-coating method. Three different PPTiO2 contents were considered, including 5 wt% (M05), 10 wt% (M10), and 15 wt% (M15). The properties of these membranes were characterized using a range of techniques, including Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX), Atomic Force Microscopy (AFM), contact angle measurements, mechanical testing and zeta potential. Performance evaluation involved filtering Reactive Red 120 (RR120) and Direct Blue 6 (DB6) solutions through the prepared composite membranes at 5 bar and demonstrates that the optimized membrane M15 exhibited remarkable water permeability of 82.13 L.m−2.h−1 bar−1 and maximum dye rejections of 92.82 % and 97.07 % for DB6 and RR120 respectively. Furthermore, molecular dynamics (MD) simulations were conducted to analyze the thermal and structural properties of the membranes. The simulations reveal that increasing the content of PPTiO2 reduced membrane pore size, consequently limiting dye mobility and diffusion. This study is the first-of-its-kind to explore the effect of PPTiO2 content on the membrane (PSF/PEI) properties; the optimized composite UF membrane showcases exceptional water permeability and dye rejection performance, making it a promising candidate for water treatment and dye removal applications.

Breaking the trade-off between selectivity and permeability of nanocomposite membrane modified by UIO66@PDA through nonsolvent thermally induced phase separation method

Developing polymer membranes with high permeability, fouling resistance, and rejection capability is a challenging task that requires the use of novel materials to enhance these properties. In this study, composite ultrafiltration membranes were fabricated by incorporating two types of metal–organic frameworks (MOFs), UIO66 and UIO66@PDA, into polyvinylidene fluoride (PVDF) using the nonsolvent thermally induced phase separation (NTIPS) method. The results demonstrated that the NTIPS method combined the characteristics of nonsolvent-induced phase separation (NIPS) and thermally induced phase separation (TIPS) to fabricate asymmetric membranes with a dense ultra-thin top layer and a bicontinuous network structure. Moreover, the introduction of 1.0 wt% UIO66@PDA into PVDF membranes yielded notable improvements in mechanical strength, thermal stability, and porosity. Concurrently, this led to a water flux rise from 182.5 to 464.7 L·m−2·h−1, and enhanced BSA and HA rejection to 96% and 83%, respectively. Additionally, there was a significant improvement in the membrane's antifouling capacity, achieving a water flux recovery ratio of 93%. This was facilitated by the increased hydrophilicity of UIO66@PDA, which attracted more water molecules and reduced membrane fouling. This work offers a solution to overcome the permeability-selectivity trade-off in membrane separation by hydrophilic modification of hydrophobic membranes, while also addressing fouling issues.

PAN/TiO2 Ultrafiltration Membrane for Enhanced BSA Removal and Antifouling Performance

Membrane separation has been widely utilized to eliminate pollutants from wastewater. Among them, a polyacrylonitrile (PAN) ultrafiltration (UF) membrane has presented outstanding stability, and distinguished chemical and thermal properties. However, UF membranes inevitably incur fouling issues during their operation procedure caused by contaminant adhesion on the membrane surface, which would restrict the operational efficiency and increase the maintenance cost. The conventional physical and chemical cleaning is not an effective technique to reduce the fouling due to the additional chemical addition and inevitable structure damage. Recently, UF membranes combined with photocatalytic materials are suggested to be a useful approach to conquer the membrane fouling issues. Herein, TiO2 nanoparticles were utilized to blend with a PAN casting solution for fabricating a composite UF membrane via a phase inversion method. With a certain TiO2 addition, the obtained membranes presented an enhancement of hydrophilicity, which could promote the water permeability and antifouling performance. The optimized M3 membrane prepared with 15.0 wt% PAN and 0.6 wt% TiO2 exhibited an excellent water permeability up to 207.0 L m−2 h−1 bar−1 with an outstanding 99.0% BSA rejection and superior antifouling property. In addition, the photocatalytic TiO2 nanoparticles endowed the M3 membrane with a remarkable self-cleaning ability under the UV irradiation. This facile construction method offered new insight to enhance the UF membrane separation performance with an enhanced antifouling ability.

Properties and preparation of TiO2‐HAP@PVDF composite ultrafiltration membranes

AbstractThe non‐solvent induced phase separation technology was introduced to formulate titanium dioxide (TiO2)‐hydroxyapatite (HAP) composite modified polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes, and research was conducted to explore the effect on PVDF UF membrane performance exerted by different addition amounts (0–1.0 wt%) of TiO2‐HAP composite. The results indicated that when 0.3% TiO2‐HAP composite was added, the composite membranes had a through‐channel structure, with a uniform pore structure on the surface, so that they possessed a certainly raised pure water flux. Specifically, in contrast to the pure PVDF membrane, 0.3%‐TiO2‐HAP@PVDF UF membrane exhibited an incremented pure water flux by 59.09%. Besides, TiO2‐HAP@PVDF UF membranes had decreased rejection rate of bovine serum albumin (BSA) together with water contact angle to 58.62% and 70.17°, respectively, compared to the pure PVDF membrane (85.52% &amp; 92.75°), showing good hydrophilicity. Several pure water flux tests on the composite UF membranes revealed that the flux tended to be stable after the 4th test. In summary, the addition of TiO2‐HAP composite is capable of efficiently ameliorating PVDF base membranes from the aspects of microstructure, hydrophilicity, antifouling properties, as well as stability, allowing a good application prospect in actual water treatment.Highlights The HAP can solve the poor adsorption of TiO2. The TiO2 can improves the interfacial adhesion between HAP and polymer. The TiO2‐HAP composite with excellent stability, corrosion resistance and et al. The TiO2‐HAP@PVDF UF membrane with anti‐pollution performance and stability.

Performance investigation on GO-TiO2/PVDF composite ultrafiltration membrane for slightly polluted ground water treatment

Performance investigation on GO-TiO2/PVDF composite ultrafiltration membrane for slightly polluted ground water treatment

Magnetic‐field‐inducedFe3O4@CNTsdispersion in the separation layer to improve the performance of composite ultrafiltration membrane

AbstractIt is of great significance to regulate carbon nanotubes (CNTs) dispersed in the separation layer of membranes to improve the properties of membranes. In this work, ferric oxides coated carbon nanotubes (Fe3O4@CNTs) are prepared by solvothermal method, and then are added to the casting solution to prepare Fe3O4@CNTs/poly(ethersulfone)/sulfonated polysulfone composite ultrafiltration membranes. The result shows that Fe3O4@CNTs migrate to the separation layer of membranes under the induction of a low‐intensity magnetic field. The surface and overall porosity of the membranes increase and the surface roughness of the membranes decreases. The contact angle of composite ultrafiltration membranes decreases from 78.0° to 60.1°, indicating an improvement of hydrophilicity. The pure water permeance of the composite ultrafiltration membranes increases from 240.1 to 524.7 L m−2 h−1while retaining a high bovine serum albumin rejection (&gt;96.8%). Moreover, the antifouling property of the composite ultrafiltration membranes is significantly improved, and the flux recovery ratio increased from 56.2% to 80.9%.

Effect of MAX Phase Ti3ALC2 on the Ultrafiltration Membrane Properties and Performance

Membrane fouling remains a major obstacle to ultrafiltration. Due to their effectiveness and minimal energy demand, membranes have been extensively employed in water treatment. To improve the antifouling property of the PVDF membrane, a composite ultrafiltration membrane was created employing the in-situ embedment approach throughout the phase inversion process and utilizing a new 2D material, MAX phase Ti3ALC2. The membranes were described using FTIR (Fourier transform infrared spectroscopy), EDS (energy dispersive spectroscopy), CA (water contact angle), and porosity measurements. Additionally, atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy (EDS) were employed. Standard flux and rejection tests were applied to study the produced membranes’ performance. Adding Ti3ALC2 reduced composite membranes’ surface roughness and hydrophobicity compared to the pristine membrane. Porosity and membrane pore size increased with the addition up to 0.3% w/v, which decreased as the additive percentage increased. The mixed matric membrane with 0.7% w/v of Ti3ALC2 (M7) had the lowest CA. The alteration in the membranes’ properties reflected well on their performance. The membrane with the highest porosity (0.1% w/v of Ti3ALC2, M1) achieved the highest pure water and protein solution fluxes of 182.5 and 148.7. The most hydrophilic membrane (M7) recorded the highest protein rejection and flux recovery ratio of 90.6, which was much higher than that of the pristine membrane, 26.2. MAX phase Ti3ALC2 is a potential material for antifouling membrane modification because of its protein permeability, improved water permeability, and outstanding antifouling characteristics.

Magnetically Grafted Carbon Nanotubes Synthesis and Its Oriented Nanochannels Construction in the Poly(Vinylidene Fluoride) (PVDF) Ultrafiltration Membranes

Carbon nanotubes (CNTs) with hollow nanochannels have attracted much attention in preparing high-performance water treatment membranes. In this paper, the grafting polymer chains, including alkynyl terminated poly(methyl methacrylate) methacrylate (PMMA) single chain and PMMA-b-poly (ethylene glycol) methacrylate [P(PEGMA)] diblock molecular chains, were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. A UV-induced click reaction was used to graft different linear polymers onto the surface of magnetic thiol-functionalized carbon nanotubes (mCNTs-SH). The poly(vinylidene fluoride) (PVDF) composite ultrafiltration membrane within the oriented nanochannels was prepared using phase inversion and magnetic field orientation. TEM and XRD results confirmed that the magnetic carbon nanotubes grafted with a diblock molecular chain had good nano-dispersion and orientation array effects in PVDF composite ultrafiltration membrane. The water contact angle of the array mCNT-g-diblock molecular chain-based composite membrane was 48.5°, significantly enhancing the PEGMA chain segments. The composite membrane with CTNs’ nanochannels attained a higher water flux. As the diblock molecular chain grafted mCNTs oriented in the membrane, the water flux reached 17.6 LMH (five times greater than the pure PVDF membrane), while the molecular weight cut-off (MWCO) for PEG1400 rejection could reach higher than 80%.

Full-Coverage Spongy HEAA/PES Composite Ultrafiltration Membrane with High Selectivity and Antifouling Performances

Selectivity and antifouling of ultrafiltration (UF) membranes are major challenges in the separation and purification of biological proteins. This work reported that full-coverage spongy poly(ether sulfone) (PES) ultrafiltration membranes assisted by the self-cross-linking of N-hydroxyethyl acrylamide (HEAA) were fabricated via a phase inversion method at room temperature. The pore structure of the UF membrane from finger-like to coverage of the spongy structure occurred by increasing the content of HEAA, which is beneficial for size-selective separation of biomolecules. The optimized M4 membrane showed a high surface porosity with a uniform pore size of 30 nm, resulting in more than 99% protein rejection rate for immunoglobulin G (IgG) but less than 20% rejection for bovine serum albumin, confirming that the molecular weight cutoff is 100k Da. Furthermore, the fabricated PES composite ultrafiltration membranes showed excellent antifouling performance and flux recovery efficiency for proteins due to the hydrophilic group of HEAA. This study provides an intelligent strategy for fouling prevention and selective isolation of proteins.

Ultrathin g-C3N4 composite Bi2WO6 embedded in PVDF UF membrane with enhanced permeability, anti-fouling performance and durability for efficient removal of atrazine

A novel Bi2WO6-g-C3N4/polyvinylidene fluoride (PVDF) composite ultrafiltration (UF) membrane (BWO-CN/PVDF) was prepared by microwave hydrothermal and immersion precipitation phase transformation method. The BWO-CN/PVDF-0.10 exhibited an outstanding photocatalytic removal rate of atrazine (ATZ) (97.65 %) under the simulated sunlight and enhanced permeate flux (1356.09 L·m−2·h−1). The multiple optical and electrochemical detection confirmed that combining ultrathin g-C3N4 and Bi2WO6 can increase carrier separation rate and prolong its lifetime. The quenching test revealed that h+ and 1O2 were the prominent reactive species. Additionally, after a 10-cycle photocatalytic process, the BWO-CN/PVDF membrane presented remarkable reusability and durability. And it showed excellent anti-fouling performance by filtering BSA, HA, SA, and Songhua River under simulated solar irradiation. The molecular dynamic (MD) simulation showed that the combination of g-C3N4 and Bi2WO6 can enhance the interaction between BWO-CN and PVDF. This work opens up a new idea for designing and constructing a highly efficient photocatalytic membrane for water treatment.

Preparation of high flux organic solvent nanofiltration membrane based on polyimide/Noria composite ultrafiltration membrane

Organic solvent nanofiltration (OSN) membrane, a type of thin film composite (TFC) membrane, is widely used in separating organic solvents, but the low permeability of organic solvents is currently challenging to solve. This experiment used cross-linked polyimide (PI) as raw material and Noria as a nanoparticle additive to prepare a composite ultrafiltration membrane through non-solvent-induced phase separation (NIPS). Noria migrated to the composite ultrafiltration membrane surface during NIPS and acted as an interlayer, which can regulate the following interfacial polymerization. Then, the nanofiltration membrane was prepared by interfacial polymerization method using the modified PI membrane as the support layer. The experimental results showed that the hydrophilicity of the PI/Noria composite ultrafiltration membrane was significantly enhanced, in addition to a significant increase in pure water flux to 239 L m-2h-1bar−1. The methanol flux of the prepared composite nanofiltration membrane could be up to 5.472 L m-2h-1bar−1, which was twice as high as that of the unmodified composite membrane, and the G250 dye retention rate remained at over 99.6%. The nanofiltration performance is excellent and has good prospects for application in OSN.