High-performance Ultrafiltration Membranes Research Articles

Dopamine hydrochloride and L-arginine Co-functionalized halloysite nanotubes for modification of polyethersulfone ultrafiltration membrane with improved separation performance

In recent years, a range of high-performance ultrafiltration membranes have been developed, but maintaining high retention without sacrificing high throughput remains a serious challenge. In this paper, functionalized halloysite nanotubes is constructed by copolymerization and by a one-step reaction of L-arginine and dopamine hydrochloride using halloysite nanotubes as carriers. Subsequently, modified polyethersulfone membranes are prepared by blending them as additives through non-solvent-induced phase transition separation. As the synthesized nanofillers is rich in functional groups, negative electronegativity, and unique structures, the study focuses on adding nanofillers’ effect on the membrane structure and physicochemical properties. The addition of appropriate nanofillers enhances the membrane surface wettability and negative electronegativity, and the enlarged internal pores and the dense layer that remains flat and homogeneous effectively promote the flux of small molecules, the retention of large molecules, and the cyclic stability of the membrane. The prepared polyethersulfone membranes demonstrate exceptional cycle stability, high separation efficiency (almost 100 % for Congo red), and significantly improved permeation performance (initial permeate flux up to 316.5 L m-2h−1). The results demonstrate the high potential of the modified prepared polyethersulfone membranes for pertinent environmental separation processes.

Enhancement of antifouling and separation properties of poly(m-phenylene isophthalamide) hybrid ultrafiltration membrane using highly crystalline poly(heptazine imide) nanosheets

A highly crystalline phase g-C3N4, namely poly (heptazine imide) (PHI) was synthesized using molten salts. A high-performance ultrafiltration membrane was prepared by blending PHI nanosheets with Poly(m-phenylene isophthalamide) (PMIA) to obtain casting solution, and further prepared by phase conversion method. Hybrid PMIA membranes were prepared by incorporating 0.02–0.10 wt% of PHI, which were further characterized by SEM, AFM, XRD, FTIR, XPS, TGA and surface zeta potential. The hydrophilicity, water flux, and rejection of bovine serum albumin (BSA) of the membrane significantly increased. For instance, the water permeability of M4 (264.6 Lm−2h−1bar−1) was about 2.3 times that of bare PMIA membrane (113.6 Lm−2h−1bar−1), while maintaining a BSA rejection of 94.7 % for a 1000 mgL−1 BSA feed solution. Moreover, the M4 membrane showed excellent antifouling performance with a flux recovery rate of up to 88.7 % and lower irreversible fouling of 11.3 %. This study may provide reference for the modulation of highly crystalline g-C3N4 structure and its application in membrane fabrication for water treatment.

Design and fabrication of high-performance ultrafiltration membranes for low-temperature conditions

The influence of cold weather conditions on ultrafiltration (UF) membrane performance is noteworthy. Investigating alterations in UF membrane fouling behavior under low-temperature conditions and developing strategies to enhance their performance holds significant importance for advancing membrane separation technology in cold regions. We initiate an exploration into how low-temperature conditions impact the permeation and separation capabilities of unmodified PES UF membranes, concurrently scrutinizing the associated influencing mechanisms. Employing molecular design, we strategically incorporate hydrophilic carboxyl-functionalized groups into the molecular structure of poly (aryl ether sulfone) materials. This method facilitates the development of a series of PAES-modified UF membranes (LTM-x%), exhibiting exceptional performance in low-temperature conditions, grounded in the principles of the hydration layer theory. In a low-temperature condition (5±1 °C), the BSA solution flux and SA solution flux of the LTM-80 membrane surpass the pristine PES membrane flux by 187.38 % and 171.82 %, respectively. Notably, compared to the solution flux at room temperature (22±1 °C), the LTM-80 membrane shows only a slight decrease in the 5±1 °C temperature (flux decline rates of 18.52 % for BSA solution and 15.12 % for SA solution), in contrast to the pronounced decline observed in the pristine PES membrane (49.24 % for BSA and 47.67 % for SA). This investigation unveils an effective and viable strategy for designing and developing high-performance UF membranes suitable for cold regions.

PH-responsive P(AA-b-SBMA)-grafted magnetic GO high-performance ultrafiltration membrane with improved antifouling tendency and cleaning efficiency

Nanocomposite ultrafiltration polysulfone membrane with pH-responsive surface was designed and synthesized using poly (AA-b-SBMA)-grafted magnetic graphene oxide (MGP) nanofiller. The obtained membranes revealed advanced antifouling, high cleaning-efficiency, and high rejection when compared to pristine PSf membranes. The novel MGP nanofiller was synthesized by copolymerization of acrylic acid and sulfobetaine monomers on the grafted magnetic graphene oxide surface by RAFT polymerization. The non-solvent-induced phase separation was used to prepare polysulfone nanocomposite ultrafiltration membranes with pH-responsive surfaces optimized by the MGP content of 0.05 to 0.3 wt% in the dope solution. The MGP content embedded within the polysulfone matrix greatly influences the water flux. The optimal 144 LMH flux of water, achieved by 0.1 wt% MGP, was almost 80 % higher compared with the pure polysulfone. The optimal MGP-modified nanocomposite membrane showed high antifouling tendency and 72 % flux recovery value. Also, when pH changed from 3 to 8, the pH-responsive membrane revealed the best water flux recovery for bovine serum albumin adsorption-desorption. Comprehensive characterization of MGP nanofiller, the modified polysulfone, and pristine membranes confirmed that the surface hydrophilicity, cross-section morphology, surface roughness, and compositions of the modified ultrafiltration membranes could be modified considerably by the incorporation of MGP nanofiller.

TiO2-PAA-SiO2 pearl chain blend modified polyvinylidene fluoride ultrafiltration membrane with excellent oil-water separation, anti fouling performance and durability

ABSTRACT In this work, a new type of composite nanoparticles, ‘pearl chain’, was developed by linking titanium dioxide and silicon dioxide by polyacrylic acid polymer chains, and the prepared TiO2-PAA-SiO2 composite nanoparticles were analysed by SEM, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and thermogravimetric analysis, zeta potential, x-ray diffraction, etc. The success of this work was verified by the successful linking of TiO2-PAA-SiO2 composite nanoparticles.TiO2-PAA-SiO2 composite nanoparticles were analysed to verify the successful attachment of pearl chains. The obtained TiO2-PAA-SiO2 were subsequently blended in different ratios to prepare polyvinylidene fluoride (PVDF) ultrafiltration membranes. The membrane performance was tested by porosity and water contact angle measurements, scanning electron microscopy, as well as experiments using bovine serum proteins and MTBE interception. The results showed that when a certain amount of TiO2-PAA-SiO2 was added, the surface wettability, porosity and permeability of the prepared modified composite membranes were significantly improved, and the BSA adsorption rate was increased from 71.59% to 80.86%, and the retention rate of MTBE was increased by 77%, in addition to showing a better anti-pollution effect (FRR: 91.07%). It was finally concluded that the prepared membranes embedded with 1.0 wt.% TiO2-PAA-SiO2 nanofillers showed good overall filtration performance, better contamination resistance and remarkable durability. The present work successfully demonstrated the feasibility of using polyacrylic acid chemical chains to connect nanoparticles with different functions to prevent particle loss and substantially enhance membrane performance, which is valuable for bridging connection of composite nanoparticles and exploring the development of high-performance ultrafiltration membranes.

Antifouling treatment enables membranes to deal with oil and grease

PPG Industries Inc, which supplies paints, coatings and speciality materials, has developed and introduced a high-performance ultrafiltration (UF) membrane and filter elements that help to improve the reuse of industrial process water.

Understanding and Designing a High-Performance Ultrafiltration Membrane Using Machine Learning.

Ultrafiltration (UF) as one of the mainstream membrane-based technologies has been widely used in water and wastewater treatment. Increasing demand for clean and safe water requires the rational design of UF membranes with antifouling potential, while maintaining high water permeability and removal efficiency. This work employed a machine learning (ML) method to establish and understand the correlation of five membrane performance indices as well as three major performance-determining membrane properties with membrane fabrication conditions. The loading of additives, specifically nanomaterials (A_wt %), at loading amounts of >1.0 wt % was found to be the most significant feature affecting all of the membrane performance indices. The polymer content (P_wt %), molecular weight of the pore maker (M_Da), and pore maker content (M_wt %) also made considerable contributions to predicting membrane performance. Notably, M_Da was more important than M_wt % for predicting membrane performance. The feature analysis of ML models in terms of membrane properties (i.e., mean pore size, overall porosity, and contact angle) provided an unequivocal explanation of the effects of fabrication conditions on membrane performance. Our approach can provide practical aid in guiding the design of fit-for-purpose separation membranes through data-driven virtual experiments.

Robust and highly hydrophilic ultrafiltration membrane with multi-branched cellulose nanocrystals for permeability-selectivity anti-trade-off property

To overcome challenges associated with the “trade-off” effect and membrane fouling, the high-performance ultrafiltration membranes were prepared by blended multi-branched nanocellulose (Multi CNC) into polyethersulfone (PES) matrix using non-solvent induced phase separation (NIPS) technology. The as-prepared composite ultrafiltration membranes have high hydrophilicity, thicker skin layer and lower negative charge due to the abundant polar groups of carboxyl (COOH) in Multi CNC. As the results, the water flux and Bovine serum albumin (BSA) rejection of the composite membranes with 1 wt% Multi CNC reached to 961.65 L/m2·h and 96.4 %, while the flux and rejection of the original PES membrane was only 702.04 L/m2·h and 86.2 % respectively, thus the “trade-off” was effectively improved by loading of Multi CNC. Moreover, the flux recovery ratio (FRR) of MCP1 (FRR = 74.08 %) was 2.1 times as much as the original PES membranes (FRR = 34.81 %) in the water-BSA-water filtration process, verified that the introduction of Multi CNC could effectively improve the anti-fouling ability of composite membranes. Such hydrophilic composite ultrafiltration membranes with robust mechanical performance could be developed for pharmaceutical and biotechnological industries.

High-Performance Ultrafiltration Membrane: Recent Progress and Its Application for Wastewater Treatment

High-Performance Ultrafiltration Membrane: Recent Progress and Its Application for Wastewater Treatment

Conductive 3D networks in a 2D layer for high performance ultrafiltration membrane with high flux-retention and robust cyclic stability

A series of highly performing ultrafiltration membranes have been recently developed, but it is still a withstanding challenge that the ultrafiltration membrane can retain both high flux and high retention ratio without sacrificing the cycle life. In this paper, we construct a novel conductive 3D network in a 2D layer for polyethersulfone membrane, which is self-assembled by graphene oxide, carbon nanotubes, and polyaniline based on the non-solvent induced phase-inversion separation method. The unique 3D network structure and the distinctive selective layer of polyethersulfone membrane possesses molecule transport channels, double-layer intercepted area, and rigid hybrid structure, which contributes effectively to the small molecule's flux, high molecule's retention, and the membrane cyclic stability. The fabricated ultrafiltration membrane exhibits high retention of solute molecules (over 99%), high flux, and extended life span and stability, due to the improvement in the anti-fouling property. Furthermore, the pseudocapacitance of the conductive polymer polyaniline is used to in-situ monitor the fouling behavior, in order to achieve precise decontamination and prolong the long-term life. The results show that the prepared membrane would have high potential applications in relevant environmental separation processes.

High performance ultrafiltration membrane by coupling magnetic migration and in-situ surface modification

Ultrafiltration (UF) membrane technology has drawn much attraction during the past decades to address the challenge of global clean water scarcity. Herein, we proposed a facile methodology to prepare a gradient polysulfone-based (PSf) UF membrane with effective antifouling properties via coupling magnetic field-assisted directional migration and in-situ hydrolysis of fluoro-agent during non-solvent induced phase separation (NIPS). The effect of GO-Fe3O4 gradient distribution and fluorosilane (FAS) in-situ surface modification on membrane morphology, hydrophilicity, porosity, water flux and antifouling properties have been investigated. Optical microscopy and SEM-EDX observations indicated that hydrophilic GO-Fe3O4 nanofiller could directionally migrate in casting solution and eventually result in gradient distribution in PSf matrix under the magnetic field. In addition, the surface enrichment of GO-Fe3O4 provided reaction sites to anchor low energy FAS via in-situ hydrolysis on the membrane surface and realized dual antifouling mechanism (fouling-resistance and fouling-release), which guaranteed UF membranes with excellent antifouling properties and remarkable long-term stability and reusability. Our study provided a new incentive to the development of high performance UF membranes by coupling magnetic migration and in-situ surface modification.

Ultralow Ti3C2TX doping polysulfate membrane for high ultrafiltration performance

Incorporating hydrophilic nanomaterial fillers into a polymeric matrix enables a high-performance ultrafiltration membrane. 2D Ti3C2TX nanosheets are promising candidates due to their hydrophilic nature and good dispersion ability in the organic solvent. In this study, novel polysulfate (PSE)/Ti3C2TX ultrafiltration membranes were prepared by non-solvent induced phase separation (NIPS) method. The phase inversion process of the PSE/Ti3C2TX casting membranes was visualized. Ti3C2TX nanosheets could tune the phase inversion process effectively and promote the phase inversion speed with an ultralow content of 0.05 wt%. As a result, the hydrophilic property and porosity of PSE/Ti3C2TX membrane could be improved. The skin layer thickness was significantly reduced, resulting in saliently ultrafiltration performance, i.e., a pure water flux (PWF) of 685 L*m−2*h−1 (LMH) with a bovine serum albumin (BSA) rejection of 97%. The proposed ultralow Ti3C2TX doping in the casting solutions method offers a versatile platform to manipulate the phase inversion progress during the industrially NIPS process, and enhanced the separation performance of ultrafiltration membranes.

Bio-inspired fabrication of highly permeable and anti-fouling ultrafiltration membranes based on bacterial cellulose for efficient removal of soluble dyes and insoluble oils

Ultrafiltration (UF) has been broadly applied for the supply of drinking water to achieve the interception of various organic, inorganic and biological pollutants. However, fouling is a ubiquitous problem when the filter is working. Thus, the development of high-performance ultrafiltration membrane with great separation abilities and anti-fouling properties is of particular importance in water treatment. In this work, we find a feasible way to use the mussel-inspired dopamine (DA) to modify the 3D web-like skeleton of bacterial cellulose (BC) in liquid phase, integrating with 2D graphene oxide (GO) nanosheets to fabricate a robust anti-fouling ultrafiltration membrane. The as formed bacterial cellulose/polydopamine/reduced graphene oxide (BC/PDA/RGO) composites showed unique superhydrophilicity and underwater superoleophobicity. For pure water flux test, the membrane exhibited high permeability of 1149.3 L m−2 h−1 under 0.1 MPa. For dyes and oils rejection experiment, the membrane revealed extraordinary contaminants resistance performances. More importantly, during cycling measurement, the membrane manifested superior anti-fouling capability and a high permeate flux recovery ratio (~96.9%) for long-term filtration processes. Therefore, this novel BC/PDA/RGO ultrafiltration membrane is expected as a promising candidate for water purification.

High rejection performance ultrafiltration membrane with ultrathin dense layer fabricated by the movement and dissolution of metal–organic frameworks

Ultrafiltration membranes have potential to solve the problems of water pollution and shortage.

High performance ultrafiltration composite membranes based on nanofibrous substrate with PDA coating and TAPS-NA immobilization

ABSTRACTIn this paper, we prepared a novel kind of high flux ultrafiltration (UF) membrane based on the phenolphthalein poly(ether sulfone)/polyvinylpolypyrrolidone (PVPP) composite membrane which the polydopamine (PDA) and N-[Tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid sodium salt were single side deposited on the PVPP layer. The results showed the coating layer endowed the composite membrane with superhydrophilicity and excellent bovine serum albumin resistance ability. The filtration of oil in water emulsion indicated the composite membranes displayed outstanding antifouling performance due to their hydrophilicity ability and surface nanoscale structures. Overall, this work offered a convenient approach to construct high performance UF membrane based on nanofibrous substrate.

Multifunctional wafer-scale graphene membranes for fast ultrafiltration and high permeation gas separation.

Reliable and large-scale manufacturing routes for perforated graphene membranes in separation and filtration remain challenging. We introduce two manufacturing pathways for the fabrication of highly porous, perforated graphene membranes with sub-100-nm pores, suitable for ultrafiltration and as a two-dimensional (2D) scaffold for synthesizing ultrathin, gas-selective polymers. The two complementary processes-bottom up and top down-enable perforated graphene membranes with desired layer number and allow ultrafiltration applications with liquid permeances up to 5.55 × 10-8 m3 s-1 Pa-1 m-2. Moreover, thin-film polymers fabricated via vapor-liquid interfacial polymerization on these perforated graphene membranes constitute gas-selective polyimide graphene membranes as thin as 20 nm with superior permeances. The methods of controlled, simple, and reliable graphene perforation on wafer scale along with vapor-liquid polymerization allow the expansion of current 2D membrane technology to high-performance ultrafiltration and 2D material reinforced, gas-selective thin-film polymers.

Selective swelling of block copolymer ultrafiltration membranes for enhanced water permeability and fouling resistance

High permeability is one of the most important pursuits of separation membranes. In this work, high-performance ultrafiltration membranes are prepared by synergetically coupling nonsolvent-induced phase separation (NIPS) and selective swelling of a block copolymer, polysulfone-block-poly (ethylene glycol) (PSF-b-PEG). NIPS is used to prepare PSF-b-PEG membranes with a thin skin layer and a fingerlike sublayer. Subsequent selective swelling generates mesopores in the skin layer and enriches PEG blocks on the surface. Compared to the membranes without swelling, the swelling-treated membranes exhibit simultaneously upgraded permeability, hydrophilicity, and fouling resistance. For instance, the permeability of the membrane swollen in 50% acetic acid at 65 °C for 1 h is doubled compared to the pristine one while the rejection is only modestly reduced. Fouling resistance of the swelling-treated membranes is also improved, which is ascribed to the enrichment of PEG on the membrane surface. We demonstrate that the performances of the membranes can be tuned in a relatively wide range by tailoring the swelling conditions, such as swelling reagents, durations and temperatures. Because of the extreme simplicity and high efficiency, this selective swelling strategy is expected to be applicable in tuning the surface properties and improving performances of many other membranes.

Polyarylsulfone-based blend ultrafiltration membranes with combined size and charge selectivity for protein separation

Current research is actively devoted to the development of high-performance ultrafiltration membranes with high permeability at maximum selectivity for dedicated separations. This work reports the preparation of polymer blend charged ultrafiltration membranes for the improvement of fractionation selectivity. Flat sheet membranes made from polysulfone and various types of sulfonated poly(arylsulfone)s were prepared via non-solvent induced phase separation. Membrane morphology, hydrophilicity and surface charge were assessed by scanning electron microscopy, contact angle and zeta potential measurements, respectively. The separation performances, i.e. selectivity factor, permeability, and permeability recovery, were evaluated by ultrafiltration of model proteins – bovine serum albumin (BSA) and hemoglobin (Hb). Results showed that the membrane charge can be tuned by adjusting the fraction of sulfonated groups via the type of sulfonated polymer in the blend used for membrane preparation. Hence, a broad range of ultrafiltration membranes with different barrier pore sizes, permeability properties and surface charge was established. Pronounced differences between the effects of different types of sulfonated poly(arylsulfone)s at the same degree of sulfonation and mass fraction in the membranes had been found and related to different barrier structures formed during phase separation. Successful separation of protein mixtures was achieved by additionally adjusting filtration parameters. Overall, this work provides guidelines for a versatile and easy method to tailor membrane properties for the selective separation of binary mixtures of biomacromolecules with nearly identical molecular weight and potentially also to solve other separation problems.

Acetyl-d-glucopyranoside functionalized carbon nanotubes for the development of high performance ultrafiltration membranes

Abstract Acetyl- d -glucopyranoside functionalized MWCNTs (gCNTs) were prepared and used in the fabrication of nanocomposite UF membranes by phase inversion process using different amounts of polysulphone, polyvinylpyrrolidone and gCNTs. The fabricated membranes were then treated with NaOMe solution in anhydrous methanol for deacetylation of 2,3,4,6-tetra- O -acetyl- d -glucopyranoside group to obtain d -glucopyranoside functional group on gCNTs. The UF membranes were characterized by different techniques to understand membrane morphology, water contact angles, thermal behaviour and other physical characteristics. The transport properties of the membranes were determined by permeating pure water, aqueous solutions of different molecular weight polyethyleneoxides and polyethyleneglycol, bovine serum albumin (BSA) solution and oil-water emulsion at 2 bar operating pressure. The deacetylated nanocomposite membrane (PSF-PVP-gCNT = 92.1–7.7–0.2 wt ratio, CM1) showed higher BSA solution flux (121 LMH) compared to the other membranes (composite membranes: 42–109 LMH; PSF-PVP = 57–87 LMH). The deacetylated nanocomposite membrane (CM1) exhibited maximum flux of 112 LMH with oil rejection of 100% for oil-water emulsion feeds. The deacetylated nanocomposite membranes showed higher flux recovery ratio (FRR = 74–90%) compared to the untreated composite membranes (FRR = 55–77%) and PSF-PVP blend membranes (FRR = 50–62%) for oil-water emulsion feeds. The d -glucopyranoside CNTs have great potential for the fabrication of high performance composite membranes with enhanced antifouling property.

Novel ultrafiltration membranes from low-fouling copolymers for RO pretreatment applications

For a consistent and reliable ultrafiltration (UF) membrane operation, the membrane flux level has always been determined conservatively so that fouling rate is controllable, and therefore, chemical cleaning requirements are minimized. A better solution is to prevent the fouling to happen in the first place by modifying the surface properties of the membrane materials. This paper presents novel approaches to improve the fouling-propensity performance of existing UF membranes based on polyethersulfone. More hydrophilic membranes and anti-adhesive membranes were developed by using various novel copolymers as base membrane materials or as an additive in the spinning process. Incorporating these copolymers, improved Multibore® fibers were produced and validated in multiple pilot trials for various applications, namely surface and wastewater purification and seawater reverse osmosis pretreatment for desalination. The paper demonstrates that, for each application, a reduced fouling propensity performance was achieved, allowing the fibers to be operated at a substantially higher flux of up to 30%. This study underscores the importance of chemistry in obtaining low-fouling and high-performance UF membranes by modifying their surface properties.