Bovine Serum Albumin Rejection Rate Research Articles

Porous organic polymer nanosheets doped multistage water channel ultrafiltration membrane: Accelerated phase inversion process and in-situ covalent crosslinking strategy

Mixed matrix membranes (MMMs) have attracted significant interest in the field of water treatment owing to their capability to integrate the scalability and processability of polymers with the selectivity of fillers. Despite the numerous advantages demonstrated by emerging nanofillers, currently developed MMMs are still limited by such as insufficient hydrophilicity, susceptibility to additive loss, and poor filler compatibility.To address these challenges, we developed a series of polyethersulfone (PES)-based MMMs featuring a hydrophilic surface and multistage water transport channels, thereby minimizing additive loss, and enhancing efficiency in water treatment processes. Through interfacial azo-coupling polymerization, we synthesized a series of hydrophilic and porous two-dimensional sulfonic acid-functionalized porous organic polymer nanosheets (NS-sPOPs) to be used as additives in the MMMs. Owing to the exceptional hydrophilicity and favorable dispersibility of NS-sPOPs in water, the nanosheets influenced phase inversion through an accelerated phase separation process, resulting in the formation of multistage channels. Polyphosphoric acid (PPA) was used for the post-crosslinking treatment of the PES/NS-sPOP membrane. Consequently, the NS-sPOPs were immobilized within the polymer matrix to ensure stable performance in subsequent use. The prepared PES/NS-sPOP membrane exhibited outstanding water permeability (pure water flux) of 493 L·m−2·h−1·bar−1, and a high bovine serum albumin rejection rate of 99.3 %. Furthermore, it exhibits consistent performance throughout a 48 h long-term stability test. Overall, the blending and crosslinking strategy of hydrophilic nanofillers enables the realization of superhydrophilic 2D nanosheet-doped multistage-water-channel MMMs with exceptional permeability and high selectivity for water purification and organic pollutant removal.

Effect of Copper Oxide Nanoparticles on the Performance of Polyvinyl Chloride Membranes

AbstractPolyvinyl chloride (PVC)/copper oxide (CuO) nanocomposite membranes were fabricated at different CuO nanoparticles loading levels using the phase inversion method. The fabricated membranes were tested through two filtration cycles in a submerged membrane system to remove bovine serum albumin (BSA) from water. Results showed that the hydrophilicity and porosity of the nanocomposite membranes were enhanced with an increase of CuO nanoparticles loading. The field emission electron microscopy images from the membrane surface demonstrated that the number and size of pores increased with addition of CuO nanoparticles. The atomic force microscopy test displayed that all nanocomposite membranes showed lower surface roughness in comparison to neat PVC membranes. The obtained results from membrane performance indicated that the irreversible fouling ratio for neat PVC membranes in the first and second cycles of filtration decreased for PVC/CuO‐1.5 membranes. Compared with the neat PVC membrane, the membrane containing CuO exhibited better capabilities such as the enhanced permeation flux, higher BSA rejection rate, and better antifouling properties.

Highly-selective hybrid ultrafiltration membranes with AlPO4-5 zeotype fillers: Effect of filler loading, morphology, and metal substitution on performance and fouling resistance

In recent years, membrane technologies have emerged as a promising solution for water treatment, particularly ultrafiltration. However, fouling remains a significant challenge in membrane applications, leading to a decline in membrane performance over time. To address this issue, the development of antifouling membranes has garnered considerable attention. By tuning their hydrophilicity, roughness, and surface charge, such membranes aim to mitigate fouling effects and extend their operational lifespan. In this work, aluminophosphate zeotype AlPO4-5 and cobalt-substituted AlPO4-5 (CoAPO-5) fillers were hydrothermally grown, their physicochemical, structural, and morphological characteristics were evaluated, and both types of fillers were incorporated into polyethersulfone (PES) membranes via phase inversion to fabricate antifouling hybrid ultrafiltration membranes. Fabrication of PES/xCoAPO-5 (y) hybrid membranes (x: Co/Al2O3 mole%, y: H2O/Al2O3 molar ratio in the synthesis mixture of the zeolite synthesis) was realized by varying the loading of the zeolite in the casting solution. Water permeance and bovine serum albumin (BSA) rejection of the developed hybrid membranes were significantly enhanced depending on the metal content, filler morphology, and loading within the membrane matrix. The maximum water permeance (688.8 L m−2 h−1 bar−1) was obtained for the membrane loaded with 6 wt% AlPO4-5 (400), which was 66 % higher than the pristine one, while a superior BSA rejection rate of 99.4 % was obtained from the membrane loaded with 6 wt% of 5CoAPO-5 (400).

Preparation of a cyclodextrin metal-organic framework (CD-MOF) membrane for chiral separation

Due to their unique properties, the efficient separation of racemic mixtures remains a great challenge. Recently, membrane separation has been demonstrated as a promising chiral separation technique with the advantages of continuous operation, high throughput, and cost effectiveness. In this work, a cyclodextrin-metal-organic framework (CD-MOF) was prepared and then composited with polyvinylidene fluoride (PVDF) polymer by the phase inversion via immersion precipitation method to form a CD-MOF/PVDF composite membrane for chiral amino acid separation for the first time. The composite membranes prepared under different conditions were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) thermogravimetric analysis (TGA)and differential scanning calorimetry (DSC). The effects of preparation conditions including CD-MOF load, polymer concentration, and casting solution temperature on the hydrophilicity, water flux, bovine serum albumin (BSA) rejection and chiral separation performance of the membrane were investigated. It is found that the composite membrane (V-5%−12) prepared with the CD-MOF load of 5%, polymer concentration of 12%, and casting solution of 70 ℃ shows the best performance with the water flux of 466.4 L/m2∙h, BSA rejection rate of 24.3% and stable 100% separation efficiency for phenylalanine (Phe) enantiomers for 4 h. The interaction energies between the CD-MOF and D-Phe and L-Phe were calculated using the Gaussian 09 program package and the chiral separation mechanism of the composite membrane was proposed at the molecular level. Our work demonstrates great development potentials of the CD-MOF/PVDF composite membrane in the chiral separation of drugs.

Influence of ethanol content and temperature in coagulation bath on the microstructure and performance of polyvinylidene fluoride ultrafiltration membranes

In this article, polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared via phase inversion method. The influence of different ethanol content and temperature in coagulation bath on the microstructure of PVDF membranes was discussed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) measurements. Rejection experiment was conducted with the bovine serum albumin (BSA) solution. The FTIR and XRD analysis showed the higher ethanol content and temperature of coagulation bath promoted the α crystal form of PVDF membranes. The increase of ethanol content in coagulation bath led to a decrease in the mean pore size and porosity and the increase of BSA rejection rate and break strength of PVDF membranes. This was because of the increase of ethanol content in coagulation bath that resulted in the formation of the more sponge-like structures and the fewer finger-like structures, which enhanced the compactness of the membranes. The PVDF membrane prepared in ethanol/pure water (60/40) coagulation bath at 20 °C showed a greater BSA rejection rate of 91.87% and break strength of 1.89 MPa with a mean pore size of 29.26 nm. Meanwhile, the increase in temperature of coagulation bath had a positive effect on the mean pore size, porosity, and hydrophilicity of PVDF membranes to a certain extent.

Fabrication of anti-fouling and photocleaning PVDF microfiltration membranes embedded with N-TiO2 photocatalysts

Polyvinylidene fluoride (PVDF) membranes are promising materials for purifying and recycling wastewater in cold regions due to their high mechanical strength and low temperature stability. However, in practical wastewater treatment services, PVDF is easily fouled by organic pollutants because of its hydrophobic characteristics. In addition, because of the large amount of reagent utilized in the conventional cleaning process, a new hydrophilic membrane with simple cleaning characteristics needs to be developed. In this work, a novel anti-fouling membrane (N-TiO2@PVDF) was obtained by implanting a N-TiO2 photocatalyst into a PVDF membrane. N-TiO2@PVDFshows a more homogeneous pore size distribution and a larger average pore diameter, which results in a higher water flux (1017.8 L/m2•h compared to 217.4 L/m2•h PVDF), higher model pollutant bovine serum albumin (BSA) solution flux and higher BSA rejection rate (92.3% compared to 81.4% for PVDF). Furthermore, N-TiO2@PVDF shows an outstanding hydrophilicity performance compared to the PVDF membrane. The water contact angle of N-TiO2@PVDF 14 decreases sharply from 93.7° (PVDF) to 53.5°, and the BSA adsorption amount decreases significantly from 1.41 mg/cm2 (PVDF) to 0.05 mg/cm2. The total fouling ratio of N-TiO2@PVDF is decreased to a value of 25.5% compared to a value of 70.3% for PVDF, and the irreversible BSA fouling ratio is even decreased to 5.8% compared to 57.2% for PVDF. This result indicates that N-TiO2@PVDF shows outstanding antifouling performance. The N-TiO2@PVDF membrane also has a photocleaning function, and the BSA flux recovery ratio reaches up to 94.7% under simulated sunlight irradiation for 2 h without additional treatment. The results obtained from hydroxyl radical (OH) detection indicate that OH degradation of organic pollutants is the dominant mechanism for the N-TiO2@PVDF photocleaning. This anti-fouling and photocleaning N-TiO2@PVDF membrane offers a solution to wastewater treatment problems of membrane brittleness and easy fouling in cold places. It can also be a good choice for the drinking water purification process.

Preparation and performance of acrylic acid grafted PES ultrafiltration membrane via plasma surface activation

A modified PES ultrafiltration membrane with excellent separation and antifouling properties was obtained after modification by remote Ar–NH3 plasma-induced acrylic acid (AA) grafting. Hydrophilic properties were characterised using water contact angle measurements. The morphology was analysed using SEM and BET measurements. Changes in the surface functional groups were determined using XPS and ATR-FTIR. The separation and antifouling properties were evaluated through a bovine serum albumin (BSA) separation experiment. The results revealed that the surface structure of the modified membrane was not destroyed, that amino groups were introduced on the surface of the PES membrane, and that AA was successfully grafted. The water contact angle decreased from 67° in the original membrane to 5 ± 0.63° in the modified membrane. The water flux increased from 30 to 93.6 L/(m2·h). The rejection rate of BSA increased from 61.5 to 93.8%, and the flux recovery rate increased from 60.0 to 92.3%.

Preparation and Characterization of Regenerated Cellulose Membrane Blended with ZrO2 Nanoparticles.

It is of great significance to search for efficient, renewable, biodegradable and economical membrane materials. Herein, we developed an organic-inorganic hybrid regenerated cellulose membrane (ZrO2/BCM) with excellent hydrophilic and anti-fouling properties. The membrane was prepared by introducing ZrO2 particles into an N-Methylmorpholine-N-oxide(NMMO)/bamboo cellulose(BC) solution system by the phase inversion method. The physi-chemical structure of the membranes were characterized based on thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). The modified regenerated cellulose membrane has the excellent rejection of bovine serum albumin (BSA) and anti-fouling performance. The membrane flux of ZrO2/BCM is 321.49 (L/m2·h), and the rejection rate of BSA is 91.2%. Moreover, the membrane flux recovery rate after cleaning with deionized water was 90.6%. This new type of separation membrane prepared with green materials holds broad application potential in water purification and wastewater treatment.

Enhancing the permeation and antifouling performance of PVDF hybrid membranes by incorporating Co–Fe hydroxide nanoparticles in reverse microemulsion

This study attempted to enhance the permeation and antifouling performance of polyvinylidene fluoride (PVDF) ultrafiltration membranes. Reverse microemulsion containing cobalt and iron (Co–Fe) bimetallic hydroxide nanoparticles was blended with the PVDF membranes to construct a novel PVDF hybrid membrane. The permeation performance, antifouling property, and long-term operational stability of the hybrid membranes were evaluated via ultrafiltration process of water flux and bovine serum albumin (BSA) rejection. Structural characterization showed that the protection endowed by reverse microemulsion made the hydroxide nanoparticles to distribute uniformly in the PVDF polymeric matrix. The introduction of well-distributed bimetallic hydroxide nanoparticles substantially improved the pore structures and hydrophilicity of the PVDF hybrid membranes, thereby enhancing their permeation performance and antifouling property. The optimal water flux of the PVDF hybrid membranes (MD-10) reached 328 L·m−2·h−1 and was 5.4-fold higher than that of neat PVDF. Moreover, the MD-10 membrane had a high a high BSA rejection rate (91.04%). After four cycles of successive fouling-cleaning processes, the water flux of the MD-10 membrane still exceeded 160 L·m−2·h−1 and was fourfold higher than that of neat PVDF. However, excessive amounts of the microemulsion could not be uniformly mixed with the PVDF membranes, thereby decreasing the permeation and antifouling performance of the PVDF hybrid membranes.

Designing of a novel polyvinylidene fluoride/TiO2/UiO-66-NH2 membrane with photocatalytic antifouling properties using modified zirconium-based metal-organic framework.

Novel polyvinylidene fluoride/TiO2/UiO-66-NH2 (PVDF/TiUN) membranes were produced by the delay phase separation method via introducing the TiO2/UiO-66-NH2 (TiUN) nanocomposite into PVDF casting solution. Interconnection of TiO2 and UiO-66-NH2 improved photocatalysis capacity and endowed PVDF/TiUN membranes with self-cleaning capability. Quantitative measurements showed that, firstly, PVDF/TiUN membranes exhibited improved photodegradation kinetics and efficiency (up to 88.1%) to Rhodamine B (RhB). Secondly, the performances of bovine serum albumin (BSA) rejection and permeation of PVDF/TiUN membranes outperformed those of other check samples, indicating enhanced hydrophilicity. Thirdly, rejection rate of BSA reached a breathtaking 98.14% and flux recovery ratio (FRR) of BSA reached a breathtaking 95.37%. Thus, given their excellent anti-contamination property and separation performance, the PVDF/TiUN membrane is very likely to be a novel water treatment membrane.

Multifunctional hybrid UF membrane from poly(ether sulfone) and quaternized polydopamine anchored reduced graphene oxide nanohybrid for water treatment

In this study, a new quaternized polydopamine anchored reduced graphene oxide (QSiPD-rGO) nanohybrid was prepared through a one-step mussel-inspired tailoring of GO using a quaternized silica precursor and dopamine. The QSiPD-rGO was applied for the first time as a nanofiller, at a significant loading rate of up to 8 wt%, to manufacture positively charged, high flux, fouling resistant and antibacterial hybrid poly(ether sulfone) (PES) ultrafiltration (UF) membranes, via non-solvent induced phase separation. A suite of tools was utilized to thoroughly characterize the nanohybrid and the membranes, including SEM-EDX, Raman, ATR-FTIR, TGA, AFM, zeta potential and contact angle measurements. The surface morphology, charge and hydrophilicity of the membranes were tuned upon integrating the nanohybrid. Consequently, pure water flux significantly increased, reaching ~ 270 L m−2 h−1 (at 1 bar) for PMQ4 with 6 wt% QSiPD-rGO loading. This was 94% higher than the corresponding flux of pristine membrane (139 L m−2 h−1, at 1 bar). The hybrid membranes also showed superior fouling resistance during the UF of 500 ppm bovine serum albumin (BSA) solution. The BSA rejection rate of the hybrid membranes was very high and uncompromised by their high flux, exceeding 98% for PMQ4. Additionally, a remarkable antibacterial activity (against E. Coli.) of the membranes was induced by the nanohybrid, with a strong correlation between this activity and QSiPD-rGO loading.

Prediction of the phenol removal capacity from water by adsorption on activated carbon.

High-performance sulfonated polysulfone (SPSf) mixed-matrix membranes (MMMs) were fabricated via a nonsolvent-induced phase separation (NIPS) method using zeolitic imidazolate frameworks-67 (ZIF-67) as a crosslinker. Acid-base crosslinking occurred between the sulfonic acid groups of SPSf and the tertiary amine groups of the embedded ZIF-67, which improved the dispersion of ZIF-67 and simultaneously improved the membrane strzcture and permselectivity. The dispersion of ZIF-67 in the MMMs and the acid-base crosslinking reaction were verified by energy-dispersive X-ray spectroscopy (EDX), X-ray diffractometry (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The pore structure analysis of MMMs indicated that filling ZIF-67 into SPSf enhanced the average surface pore sizes, surface porosities and more micropore in cross-sections. The crossflow filtrations showed the MMMs have higher pure water fluxes (57 to 111 L m-2 h-1) than the SPSf membrane (55 L m-2 h-1) but also higher bovine serum albumin (BSA) rejection rate of 93.9-95.8%, a model protein foulant. The MMMs showed a higher water contact angle than the SPSf membrane due to the addition of hydrophobic ZIF-67 and acid-base crosslinking, and also maintained high thermal stability evidenced by the thermogravimetric analysis (TGA) results. At the optimal ZIF-67 concentration of 0.3 wt%, the water flux of the SPSf-Z67-0.3 membrane was 82 L m-2 h-1 with a high BSA rejection rate of 95.3% at 0.1 MPa and better antifouling performance (FRR = 70%).

Photocatalytic antifouling properties of novel PVDF membranes improved by incorporation of SnO2-GO nanocomposite for water treatment

Excellent separation performance and anti-contamination of novel SnO2-graphene oxide/polyvinylidene fluoride (SnO2-GO/PVDF) membranes with complete sponge-like pores were produced by the delay phase conversion method via introducing the nanocomposite (SnO2-GO) into casting solution of PVDF, in which the interconnection of SnO2 and GO was able to improve photocatalysis capacity and entrust modified membranes with self-cleaning capability. The SnO2-GO/PVDF membranes exhibited enhanced effectiveness of photodegradation (increased approximately 60-80%) and superb photodegradation kinetics to bovine serum albumin (BSA) in comparison with modified membranes replenished with GO and SnO2, respectively. Furthermore, the BSA rejection and permeation of SnO2-GO/PVDF membranes were also superior over other check samples on account of the enhanced hydrophilicity, special sponge-like pore structure and photodegradation capacity. Besides, the rejection rate of BSA attached breathtaking 97.2% under high flux (363.2 L m−2 h−1). Hence, the SnO2-GO/PVDF membranes could possess ample potentiality as the younger generation of multifunctional antipollution membranes for water treatment in the foreseeable future.

Uncovering the effects of PEG porogen molecular weight and concentration on ultrafiltration membrane properties and protein purification performance

Developing ultrafiltration (UF) membranes for protein purification requires a critical understanding of the pore engineering and active-layer morphological control. In this study, we systematically explored the use of polyethylene glycol (PEG) with molecular weights (MW, 600–6000 g⋅mol−1) and concentration (3–7.5 wt%) as a pore modifier to prepare polyvinyl difluoride (PVDF) membranes via the non-solvent phase-inversion process. The membranes demonstrated a high degree of control of the structure-property-performance relationship for improving the water flux, bovine serum albumin (BSA) rejection and antifouling properties. We found that the morphology of PEG-modified membranes showed the membrane surface crystal spherulite remarkably decreased, whilst surface pore size increased with increasing porogen MW. Similarly, the increase in membrane pore size correlated very well with porogen MW and concentration exponentially and linearly respectively. Furthermore, the PEG-MW membrane series showed a flux and rejection trade-off, whereas the PEG-concentration membrane series can produce a high BSA rejection and improve the flux owing to the presence of a dense active layer. Overall, the optimized membrane with the best protein separation properties was produced by using 6 wt% PEG with 600 g⋅mol−1, which reached a competitive permeate flux of ~60 LMH⋅bar−1, with excellent flux recovery rate of >90%, and a high BSA rejection rate of 90% at the end of the three test cycle. The results in this study have elucidated and advanced the fundamental knowledge of the interrelationship between porogen and membrane property-performance.

Surface modification of high-rejection ultrafiltration membrane with antifouling capability using activated oxygen treatment and metallic glass deposition

Polysulfone (PSf) composite ultrafiltration membranes were subjected to Ar/O2 plasma assisted oxygen activation and then coated with various forms of metallic glass (W50Ni25B25, Zr60Cu25Al10Ni5, and Pd74Si14Cu12). The activated oxygen treated PSf ultrafiltration membrane was strongly hydrophilic, with pure water flux (PWF) of 350.7 L m−2 h−1 and bovine serum albumin (BSA) rejection of 83%. The application of metallic glass (MG) to the surface of the polysulfone composite membrane using low-power radio-frequency magnetron sputtering improved the BSA rejection rate (ranging from 98.6 to 99.9%) with only a slight reduction in PWF: tungsten-based MG (321.5 L m−2 h−1), zirconium-based MG (215.6 L m−2 h−1), and palladium-based MG (181.3 L m−2 h−1). The membrane with the tungsten-based coating achieved remarkable PWF, BSA rejection, and antifouling performance, due primarily to high surface hydrophilicity (water contact angle of 24.2°) and a strongly negative surface charge. Overall, the proposed metallic glass/polysulfone composite membranes achieved moderately high PWF and protein rejection with incredible antifouling competence, even under extended (multi-cycle) fouling conditions.

Influence of bore fluid composition on the physiochemical properties and performance of hollow fiber membranes for ultrafiltration

Porous hollow fiber polysulfone (PSf) membranes were fabricated via a phase-inversion process and their performance during ultrafiltration (UF) was evaluated. The effects of the composition and concentration (0–50%) of different bore fluid mixtures, including N-methyl-2-pyrrolidone (NMP)/water, glycerol (G)/water, and ethylene glycol (EG)/water (in comparison with pure deionized water), on the structure, physicochemical properties, and performance of the fabricated membranes was investigated. Using these various bore fluid mixtures altered the thermodynamic and kinetic properties of the phase inversion system, and changed the morphology and structure of the fabricated membranes, especially on the lumen side. Increasing concentrations of NMP, G, and EG in the bore fluid resulted in increased pore size, porosity, and hydrophilicity. These bore fluid mixtures exhibited a strong influence on the perm-selectivity of the as-spun hollow fiber membranes. The membrane fabricated using 50% NMP/water as the bore fluid mixture exhibited the highest water flux of 166.98 LMH with a bovine serum albumin rejection rate of more than 97%. Overall, this study introduces an easy and effective way to control the structure of the membrane through bore fluid modification and shows how the inner skin layer properties can have a remarkable effect on water permeance, even in the out-in filtration test.

G-CNTs/PVDF mixed matrix membranes with improved antifouling properties and filtration performance

Although carbon nanomaterials have been widely used as effective nanofillers for fabrication of mixed matrix membranes (MMMs) with outstanding performances, the reproducibility of the fabricated MMMs is still hindered by the non-homogenous dispersion of these carbon nanofillers in membrane substrate. Herein, we report an effective way to improve the compatibility of carbon-based nanomaterials with membrane matrixes. By chemically conjugating the oxidized CNTs (o-CNTs) and GO using hexanediamine as cross-linker, a novel carbon nanohybrid material (G-CNTs) was synthesized, which inherited both the advanced properties of multi-walled carbon nanotubes (CNTs) and graphene oxide (GO). The G-CNTs incorporated polyvinylidene fluoride (PVDF) MMMs (GCNTs/PVDF) were fabricated via a non-solvent induced phase separation (NIPS) method. The filtration and antifouling performances of G-CNTs/PVDF were evaluated using distillate water and a 1 g/L bovine serum albumin (BSA) aqueous solution under 0.10 MPa. Compared to the MMMs prepared with o-CNTs, GO, the physical mixture of o-CNTs and GO and pure PVDF membrane, the G-CNTs/PVDF membrane exhibited the highest water flux up to 220 L/m2/h and a flux recovery ratio as high as 90%, as well as the best BSA rejection rate. The excellent performances should be attributed to the increased membrane pore size, porosity and hydrophilicity of the resulted membrane. The successful synthesis of the novel nanohybrid G-CNTs provides a new type of nanofillers for MMMs fabrication.

Amphiphilic PVDF‐g‐PDMAPMA ultrafiltration membrane with enhanced hydrophilicity and antifouling properties

ABSTRACTIt is easy to adsorb the pollutants from water owning to the hydrophobicity of the poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membrane. To improve the hydrophilicity of the PVDF UF membrane, a novel amphiphilic copolymer PVDF‐g‐poly‐N‐(3‐dimethylaminopropyl)methacrylamide] (PDMAPMA) was developed. The amphiphilic PVDF‐g‐PDMAPMA was synthesized with PVDF and N‐(3‐dimethylaminopropyl)methacrylamide (DMAPMA) via free‐radical polymerization, and characterized by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance. The scanning electron microscopy and energy dispersive X‐ray spectroscopy were used to characterize the structure morphologies and elementals of the blend PVDF membranes, respectively. The pure water flux (PWF), molecular weight cutoff, and bovine serum albumin (BSA) solution filtration experiments were tested to evaluate the permeation performance and antifouling properties of the membranes. The experimental results showed that the PWF was 263.1 L m−2 h−1, BSA rejection rate was 98.1% and flux recovery rate was 95.1% of the prepared blend membrane which had obvious improvement compared with the pristine PVDF membrane (17.3 L m−2 h−1, 91.0, and 83.8%, respectively). The antibacterial activity test showed the prepared blend membrane had good potency against microorganisms. A novel hydrophilic PVDF membrane with good antibacterial properties was developed and would be promising for wastewater treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48049.

A Superhydrophilic and Anti-Biofouling Polyphenylene Sulfide Microporous Membrane with Quaternary Ammonium Salts

Polyphenylene sulfide (PPS) membranes were modified by chloromethylation and quaternary amination reaction to prepare a hydrophilic PPS microporous membrane. The structures of the modified PPS membranes were characterized by the use of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The results showed that the modified membranes maintain the same microporous structures as the PPS membrane. The hydrophilicity of the modified membranes was significantly improved compared to that of the PPS membranes, and the water flux of N-methylimidazole modified membranes, triethylamine modified membranes, and both mixture modified membranes achieved 110.475, 168.94, 150.59 L·m−2·h−1, respectively. The quaternary amination of the PPS membranes made much less bovine serum albumin (BSA) pollution accumulation on the top surface of the modified membranes, and there was a significant improvement, to 94%, in the BSA rejection rate. Most importantly, the antibacterial activity of the modified membranes was effectively improved, and the bactericidal rate was elevated to above 80% in comparison with pure PPS membranes, which was attributed to the introduction of quaternary ammonium salts and imidazolium salts in out-surface of the membranes.

Facile and efficient in situ synthesis of silver nanoparticles on diverse filtration membrane surfaces for antimicrobial performance

Membrane biofouling remains a major limiting factor for the membrane-based water purification technology. The development of antibacterial membrane surfaces is very important for membrane biofouling mitigation. In this study, we developed a one-pot method of synthesizing silver nanoparticles (Ag NPs) and immobilizing them onto membranes via simply soaking the membranes in a mixture solution of silver nitrate, poly (ethylene glycol) methyl ether thiol (mPEG-SH) and dopamine. Results illustrate that mPEG-SH works as a ligand to slow down the reduction process of silver ions by dopamine for the synthesis of Ag NPs in a controllable manner and also the prevention of Ag NPs aggregation in solution. Moreover, the Ag NPs could be in situ immobilized onto polysulfone ultrafiltration membrane, glass fiber membrane and stainless steel, regardless of their surface properties, but the size of Ag NPs was affected by the substrates. In addition, the Ag NPs immobilization on the polysulfone ultrafiltration membranes increased the bovine serum albumin rejection rate of membrane by 16%, but decreased membrane permeability by 14% compared to that of the pristine membranes. The Ag NPs containing membranes exhibited outstanding antibacterial properties with more than 90% antibacterial efficiency against both Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus. During the filtration test, the silver release from the Ag NPs containing polysulfone ultrafiltration membranes was very slow and the total accumulation of silver ions released from the membranes was only 7% of its initial Ag NPs loading after 24 h filtration operation. The silver ion concentration in the permeate water was 0.35 ± 0.16 ppb, far below the maximal contaminant limit of silver ions in drinking water with no risk for the application of Ag NPs incorporated membranes to treat water. Our work provides a facile and universal approach of synthetizing and simultaneously immobilizing Ag NPs onto diverse membranes for antibacterial properties.