High-performance Membranes Research Articles

High-performance hydrogel membranes with superior environmental stability for harvesting osmotic energy

A collection of innovative nanofluidic systems has been developed to harness Gibbs free energy and convert it into osmotic energy. Nevertheless, these systems frequently encounter challenges such as low output power density, inadequate mechanical stability, and diminished performance in extreme conditions. In this work, we utilized a simple thermal polymerization method to fabricate a charged phytic acid (PA)–acrylic acid (AA)–3-sulfopropyl acrylate potassium salt (SPAK) hydrogel (PASH) membrane with anti-drying and anti-freezing properties, alongside mechanical stability. Using a silicon window with a testing area of 3 × 10−8 m2, a high power density of 30.94 W/m2 was achieved in artificial seawater and river water environments (0.5/0.01 M NaCl). Notably, an even higher power density of 103.9 W/m2 was attained in artificial saline lake and river water environments (5/0.01 M NaCl). Meanwhile, the PASH membrane demonstrated outstanding performance in low temperatures and various acidic and alkaline environments, offering the potential for osmotic power generation in extreme conditions. This work provides essential theoretical foundations and experimental evidence for the development of sustainable osmotic energy conversion technologies, contributing to the advancement and innovation in the field of blue osmotic energy.

High-performance proton exchange membrane derived from N-heterocycle poly(aryl ether sulfone)s with ether-free hydrophilic blocks and exhibiting good stability and proton-conducting performance

The trade-off issue between proton conduction properties and stability is a constraint on the commercial application of non-fluorinated proton exchange membranes for fuel cells. To alleviate the issue, the multi-block N-heterocycle poly(aryl ether sulfone)s with ether-free hydrophilic blocks (b-SPDPESs), which is composited by diphenyl sulfone moieties and biphthalazindione structures with dense pendant benzenesulfonic groups, are developed to prepare high-performance membranes. The self-assembly effect of block copolymers not only improves the membrane stability but also constructs regular proton conduction channels. Moreover, the conduction channel consists of hydrophilic blocks without ether bonds, which effectively improves the tolerance of the membrane to radicals. The hydrogen-bond network between sulfonic groups and N-heterocycles in the channel improves the proton conduction efficiency, inhibits the swelling of the membrane, and improves the stability of the membrane. As a result, the swelling degree of b-SPDPESs membrane is only 15.8 %, the proton conductivity is as high as 238 mS cm−1, the membrane aging broken time at 80 °C is between 4 and 6.6 h, and the fuel cells loading the membranes and feeding with hydrogen and air perform the max power density of between 0.65 and 1.25 W cm−2. Modulating the sequence structure of chains and constructing multiblock polymers containing ether-free N-heretrocyclic blocks with sulfonic groups improve the stability of membranes while ensuring their proton conductivity.

Co-sintering fabrication of ceramic whiskers enhanced SiC membranes for high-efficiency dust-laden gas filtration

Application of silicon carbide (SiC) ceramic membrane in industrial dust-containing gas filtration has been widely explored. However, its limited gas permeance and complex sintering process hinder its application. In this work, two types of SiC whisker-reinforced ceramic membranes, namely, whisker ceramic membranes (WCMs) and whisker/particle composite ceramic membranes (WPCMs), were prepared using a co-sintering process. By optimizing the co-sintering temperature and SiC whisker contents, defect-free and uniform ceramic membranes were obtained. The mean pore size of WCMs was 12.2 μm with a gas permeance of ∼ 478.0 m3·m−2·h−1·kPa−1. The WPCMs exhibited a mean pore size of 3.3 μm with a gas permeance of ∼ 288.0 m3·m−2·h−1·kPa−1. SiC whiskers interlaced and connected within membranes, forming a network structure that not only effectively prevented delamination or deformation of the membrane during the co-sintering process but also significantly enhanced the gas permeance of membranes. Additionally, SiC whiskers improved the overall bending strength of membranes and enhanced the rejection of dust particles in the dust-laden gas. The resulting WCMs and WPCMs showed excellent chemical stability and thermal shock resistance. Moreover, the optimized membranes achieved a removal efficiency of 99.99 % for macro (15 μm), micro (2.5 μm), and nano (300 nm) solid particles in the dust-laden gas. This work fabricated high-performance SiC whisker-reinforced membranes that were particularly suitable for gas purification.

Enhanced proton transfer in proton exchange membrane fuel cells via novel nanocomposite membrane incorporating (3-Mercaptopropyl)trimethoxysilane-graphene oxide and basic amino ligands: A synergistic acid-base approach

A nanocomposite polymer electrolyte membrane (MGC) was synthesized by blending MPTS (HS(CH2)3Si(OCH3)3) and graphene oxide (GO) nanosheets at varying weight ratios (91.5 to 9.5, respectively) for proton exchange membrane fuel cell (PEMFC) applications. By covalently modifying the GO support with MPTS through a silane modification process, the acidic MGC matrix is formed. The blending process, with ultrasonication and vigorous stirring, initiates two significant reactions in reactive MPTS: first, the conversion of methoxy groups (Si–OCH3) to silanols (Si-OH); second, the potential condensation of silanol groups to form siloxane bonds (Si–O–Si), followed by oxidation of sulfhydryl groups to sulfonic acid (-SO3H) groups by hydrogen peroxide. The resulting -SO3H groups connected to the siloxane network (Si-O-Si) adjacent to the GO. Two basic amino ligands – dopamine, and aminopropyl trimethoxysilane (APTES) were incorporated into the MGC matrix to establish acid-base pairs, promoting swift proton transport. These additions, at weight ratios of (0.5, 1, 2, and 7) wt%, synergistically contributed to the MGC matrix, forming effective proton channels. Various analytical techniques, including field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS), were employed to assess the impact of functionalized basic amino groups on the MGC matrix. Notably, the MGC membrane containing 2 wt% of PDA as basic amino ligands exhibited optimal performance, showcasing an in-plane proton conductivity of 115.10 mS cm-1 under fully hydrated conditions at 90 °C, and the maximum power density (MPD) of 170.74 mW cm-2 with a current density of 1051.46 mA cm-2 at 60 °C and 100 % relative humidity (RH). In contrast, the MGC membrane, devoid of amino ligands, exhibited a comparatively low in-plane conductivity of 44.32 mS cm⁻¹ under identical conditions at 90 °C. Additionally, it recorded the MPD of 48.5 mW cm⁻², corresponding to a current density of 313.25 mA cm⁻² at 60 °C and 100 % RH. This study introduces an innovative approach for developing high-performance nanocomposite membranes for PEMs and related applications.

A readily accessible quaternized cellulose filter paper with high permeability for IgG separation

Anion-exchange chromatography (AEC) is recognized as a highly effective approach for the purification of immunoglobulin G (IgG). This study introduces an innovative strategy that employs waste cellulose filter paper in the production of AEC media. A quaternized cellulose fiber membrane (CFM-QCS) was successfully fabricated that cellulose fibers were as a structural framework, glutaraldehyde (GA) as a crosslinking agent, and quaternary chitosan (QCS) as a modifying agent. Morphological and chemical characterization revealed that GA and QCS were uniformly crosslinked on the surface of the cellulose fibers, resulting in excellent mechanical properties in both dry and wet states. Benefiting from its 3D network scaffold structure, CFM-QCS demonstrated a high adsorption capacity for bovine serum albumin (BSA), with static and dynamic adsorption capacities of 605.15 mg/g and 88.63 mg/ml, respectively. After treated with extreme conditions and 10 cyclic adsorption and elution, the adsorption capacity of CFM-QCS remains almost unchanged, highlighting its excellent stability. Additionally, a CFM-QCS packed chromatography column exhibited high flux of 10.38 L/h at 0.1 MPa, which can efficiently separate IgG from a mixed solution in the presence of BSA and IgG by gravity-driven. This work presents a straightforward approach for preparing high-performance ion-exchange chromatography membranes for IgG separation.

Fabrication of Hofmann-type metal-organic framework based mixed-matrix membranes for efficient CH4/N2 separation

The analogous physical and chemical properties of methane (CH4) and nitrogen (N2) pose a great challenge for their separation. Mixed-matrix membranes (MMMs), combining the good separation performance of fillers and easy processability of polymers, are expected to address this challenging task. In this work, one Hofmann-type metal-organic framework (MOF), CoNi-DABCO, featuring abundant oppositely adjacent open metal sites, narrow pore size, and strong binding affinity toward CH4, is introduced into the polymer of polydimethylsiloxane to fabricate MMMs. The presence of CoNi-DABCO in the membranes could enhance the adsorption capacity for CH4, thus facilitating the transport of CH4 molecules through the membranes. Specially, the MMM containing 20 wt% CoNi-DABCO displays a high CH4 permeability of 1285 Barrer and maintains a good CH4/N2 mixed-gas selectivity of 3.7. Furthermore, the MMMs show good pressure resistance (up to 10 bar) and long-term stability for 30 days. This study suggests the potential of Hofmann-type MOF in the development of high-performance membranes for CH4/N2 separation.

High-Performance Membranes Based on Spherical-Beaded Nanofibers and Nanoarchitectured Networks for Water-in-Oil Emulsion Separation.

High-performance separation materials for oil-water emulsions are crucial to environmental protection and resource recovery; however, most existing fibrous separation materials are subject to large pore size and low porosity, resulting in limited separation performance. Herein, we create high-performance membranes consisting of spherical-beaded nanofibers and nanoarchitectured networks (nano-nets) using electrostatic spinning/netting technology, for water-in-oil emulsion separation. By manipulating the nonequilibrium stretching of jets, spherical-beaded nanofibers capable of generating a robust microelectric field are fabricated as scaffolds, on which charged droplets are induced to eject and phase separate to self-assemble nano-nets with small pores. Benefiting from 3D undulating networks with cavities originating from 2D nano-nets supported by 1D spherical-beaded nanofibers, the membranes exhibit under-oil superhydrophobicity (>152°), a striking separation performance with an efficiency of >99.2% and a flux of 5775 L m-2 h-1, together with wide pressure applicability, antifouling, and reusability. This work may open up new horizons in developing fibrous materials for separation and purification.

Maleimide-induced crosslinking of polyimide membranes for high gas separation performance and plasticization resistance

Trade-off effect and plasticization are the key issues confronted in the area of membrane separation when dealing with applications involving high-pressure, soluble gases like CO2. In this study, a novel diamine (TAPA-MAA) was synthesized derived from tris(4-aminophenyl)amine (TAPA) and maleic anhydride (MA). This diamine was copolymerized with DAM (2,4,6-trimethylbenzene-1,3-diamine) and 6FDA (4,4′-(hexafluoroisopropylidene)diphthalic anhydride) to form the polyimide (PI) membrane containing maleimide (MI) cross-linking sites via chemical imidization way. Then, under the action of heat treatment, the crosslinked PI (cPI) membrane was constructed since the MI crosslinking initiates a radical cycloaddition reaction to form a succinimide-linked structure, and named as cPSI membrane for short. Further, an increase in the ratio of TAPA-MAA gives rise to the resultant cPSI membrane with elevated cross-linking density. The obtained cPSI membranes showed significantly enhanced gas selectivities and superior anti-plasticization property compared to the un-crosslinked PI membranes due to the MI-induced crosslinking reaction in the PI main chain, resulting in a marked increment (24 %) in ultra-microporosity (<7 Å) and a reduction in the d-spacing value (6.10 Å vs 5.80 Å), generating a strong molecular sieving effect. Meanwhile, the highly interconnected covalent structure formed by the MI-induced crosslinking will suppress the plasticizing phenomenon induced by high-pressure soluble gases. The typical membrane (cPSI-3:7-350) possessed great CO2/CH4 separation performance, CO2 permeability of 334.4barrer and a CO2/CH4 selectivity of 61.9 that is exceeded the 2008Roberson upper bound, along withCO2 plasticization pressures above 44 bar. Besides, its mixed CO2/CH4 separation performance exceeded the 2018 upper gas mixture limit when the upstream pressure changed from 2-20 bar. This study provides valuable insights for the design of PIs containing MI cross-linking sites, which can enhance the performance of membrane-based gas separation.

Facile construction of polyacrylate membranes with pendent zwitterionic side-chains for high proton conduction

Designing high-performance proton exchange membranes for fuel cells has received tremendous interests and acquired plentiful fruits. However, the complicated preparation process and consequently high cost limit their practical application. This study endeavored to facilely construct a novel type of proton exchange membrane based on polyacrylates which decorated with pendant zwitterionic groups. Chemical structure and micro-morphology of these newly prepared membranes, namely SBPA-x (x = 0, 20, 30,40), were characterized by 1HNMR, FT-IR, XPS, SEM and AFM. Swelling ratio, water uptake and ion exchange capacity were found to be positively correlated with the contents of zwitterionic groups. The hydrophilic zwitterionic groups in the membrane formed a continuous water pathway, which contributed to the proton conductivity. Particularly, SBPA-40 membrane showed the highest proton conductivity of 78.6 mS/cm and the smallest activation energy Ea as 16 kJ/mol at 80 °C and 90 % relative humidity. On the other hand, the other application properties, such as thermal stability, mechanical property and oxidation stability, were also evaluated. Results demonstrated that all the membranes possessed good thermal stability within 300 °C and presented satisfactory mechanical performance by bending and twisting. Besides, the observed power density and open circuit voltage of SBPA-40 membrane were 58.3 mW/cm2 and 0.77 V at 30 °C. In conclusion, the zwitterionic polyacrylate membranes could have prospective application in proton exchange membrane fuel cells.

Zinc-imidazole-based metal-organic framework nanosheet membrane for H2/O2 separation

Abstract Metal-organic framework (MOF) nanosheets are promising candidates for molecular sieve because of their structural diversity and minimized mass transfer barrier. However, design of appropriate MOF nanosheets and preparation of high-performance MOF nanosheet-based membranes, especially for gas separation, remains great challenges. Structural degradation may simultaneously occur with conventional exfoliation method, which has hindered its widespread application in high-performance molecular sieve membrane preparation. Even if nanosheets could be stacked, grain boundaries would form between the nanosheets, which could be applied to liquid separation but not to gas separation. To address these challenges, we applied bottom-up growth of Zn2(benzimidazole)4 nanosheet to fabricate defect-free membranes. Zn2(benzimidazole)4 is composed of benzimidazole-zinc tetrahedral units and layers are connected by van der Waals interaction. At first, the Zn2(benzimidazole)4 nanosheets were deposited onto a porous support to prepare gutter layer. Next, Zn-based amorphous layer was coated on the gutter layer and crystallized by benzimidazole vapor treatment. Highly oriented Zn2(benzimidazole)4 nanosheet based membranes were fabricated by anisotropically controlling crystallization. The prepared Zn2(benzimidazole)4 nanosheet-based membranes show separation performance in hydrogen purification with H2/O2 ideal separation factor of 11.6 and H2 permeance of 5650 GPU.

High-performance polyurea nanofiltration membrane for waste lithium-ion batteries recycling: Leveraging synergistic control of bulk and interfacial monomer diffusion

The development of high-performance nanofiltration (NF) membranes with extreme chemical stability is urgently needed for the recovery of spent lithium. In this study, a series of polyurea membranes with high lithium recovery efficiency and pH stability were fabricated by zone-regulated interfacial polymerization (IP). The reaction inhibitor Cu2+ in the bulk aqueous phase reduces IP intensity by reversibly binding to the amino groups of polyethyleneimine monomers through chelate bonds. Meanwhile, surfactant promote the uniform diffusion of macromolecular aqueous monomers at the phase interface. The milder polymerization reaction and the more stable phase interface endow the polyurea membrane (NF10k PEI-SDS-Cu2+) with higher water permeance (2.1 L m-2 h-1 bar-1), desirable MgCl2 rejection (94.7%), and excellent fabrication repeatability. Moreover, the membrane demonstrates stable separation selectivity for Co2+/Li+ and SO42-/Li+ under conditions of 0.05 mol L-1 H2SO4 and 2 mol L-1 LiOH, respectively. Our study provides a facile method for constructing NF membranes with extreme pH stability and confirms the feasibility of membrane-based lithium recovery.

A novel TFNi pervaporation membrane with g-C3N4 quantum dots for high-efficiency IPA dehydration

Pervaporation (PV) shows significant potential for the highly selective isopropanol (IPA). The pursuit of developing PV membranes with outstanding separation effect and enduring high purity permeation is an indispensable goal. Based on polyamide (PA) separation layers, a polydopamine (PDA) mixed g-C3N4 quantum dots (gCNQDs) coating as the interlayer was deposited onto a porous ceramic hollow fiber substrate to fabricate thin-film nanocomposite membranes with an interlayer (TFNi). The nanocomposite interlayer enabled the formation of a smoother and highly separated selective polyamide layer. The separation factor exhibited a 31-fold enhancement with the augmentation of the blending fraction of gCNQDs during the PDA coating process. The resulting TFNi membrane attained an exceedingly high separation factor of 10270 ± 90 with a permeate water concentration of 99.9% and demonstrated a satisfactory flux of 1.40 ± 0.08 kg⋅m-2⋅h-1 during the PV process of 90 wt% IPA dehydration at 60 °C. This study presents a fresh perspective on the implementation of nanocomposite interlayers, which is expected to expand the application of high-performance TFNi membranes in PV dehydration processes.

Synthesis of poly(terphenyl-co-dibenzo-18-crown-6 methylimidazole) copolymers for high-performance high temperature polymer electrolyte membrane fuel cells

This study focuses on the development of high temperature polymer electrolyte membranes (HT-PEMs), which are essential components for HT-PEM fuel cells (HT-PEMFCs). While phosphoric acid (PA) doped polybenzimidazole (PBI) has been recognized as a successful HT-PEM, it faces several challenges, including the use of carcinogenic monomer, complex synthesis processes, and poor solubility in organic solvents. To produce more cost-effective, easily synthesized, and high-performance alternatives, this study utilizes a straightforward superacid-catalyzed Friedel-Crafts reaction to synthesize a series of poly(terphenyl-co-dibenzo-18-crown-6 methylimidazole) copolymers, referred to as Co-x%TP-y%CE-Im, using p-terphenyl, dibenzo-18-crown-6 and 1-methyl-1H-imidazole-2-formaldehyde as monomers. The copolymerized hydrophilic and bulky crown ether units introduce substantial free volume and multiple interaction sites with PA molecules, as indicated by theoretical calculations. Additionally, the formation of microphase separation structures, confirmed by atomic force microscope (AFM) and transmission electron microscope (TEM), contributes to the enhanced performance of these membranes. For instance, after immersion in 85 wt% and 75 wt% PA solutions, the Co-90%TP-10%CE membrane achieves PA doping contents of 200 % and 169 %, achieving high conductivities of 0.092 S cm−1 and 0.054 S cm−1 at 180 °C, while maintaining tensile strengths of 6.5 MPa and 7.5 MPa at room temperature. Without the need for humidification or backpressure, the peak power density of an H2-O2 cell equipped with Co-90%TP-10%CE/169%PA membrane with a thickness of 79 μm reaches an impressive 1018 mW cm−2 at 210 °C. These results demonstrate new materials and insights for the development of high-performance HT-PEMs.

Tubular nanofiber membranes combined with Z-scheme CuS@Co3S4 heterojunction catalyst for high-efficient removal of polyvinyl alcohol from waste water with high COD

Polyvinyl alcohol (PVA), a typical water-soluble polymer with huge global production, is becoming one of the most ubiquitous pollutants and indeed the villain of the piece contributing high chemical oxygen demand (COD) in wastewater. Membrane technology is an effective method for wastewater purification, in particular, with the combination of peroxymonosulfate (PMS)-assisted advanced oxidation or photocatalytic process, is capable of maintaining high water flux and anti-fouling. Herein, a ZIF-67 derived Z-scheme CuS@Co3S4 heterojunction catalyst immobilized by poly (m-phenylene isophthalamide) (PMIA) tubular nanofiber membrane (CuS@Co3S4/PMIA-TNM) is designed using a polyester braided tube as interior reinforcement. The resultant membrane features with outstanding superhydrophilicity and commendable porosity (82.1%), leading to a significantly enhanced permeability (water flux > 82.3L·m-2·h-1). Meanwhile, the membrane shows promising PVA removal efficiency (> 99.9%) with a high COD removal efficiency (~ 83.4%) and enhanced antifouling capacity (flux recovery ratio > 99.7%) with the assistance of PMS driven by an ultra low-power LED lamp. The universal applicability and environmental adaptability are also verified in various reaction conditions. In terms of ecotoxicological impacts of the PVA wastewater before and after treatment on aquatic organisms, Zebrafish embryonic development dynamically demonstrated that the treated PVA waste water by the developed hybrid membrane is healthy for fish to grow. Our study definitely opens up a new avenue to develop high-performance catalytic membranes for PVA-based wastewater treatment.

Two-dimensional montmorillonite membranes with controllable sub-nanochannel for precise separation of mono/divalent cations

Two-dimensional (2D) membranes with highly ordered nanoscale interlayer channels have received considerable attention to emerge as a desirable candidate for ions separation application. However, the unstable channel height of 2D membranes in aqueous environment results in labile ions separation selectivity. Herein, tetraethylenepentamine (TEPA) is introduced to the 2D montmorillonite (MMT) membrane, which plays a significant role in the precise control of channel height. This is due to that protonated TEPA can exchange into the interlayer of MMT membranes and the hydrophobic chain of TEPA can prevent water molecules from entering the channel. Based on the precise control of channel height by using different amounts of TEPA, the optimum channel heights with undetectable Mg2+ ions were found. Furthermore, the suitable channel heights for K+/Mg2+, Na+/Mg2+ and Li+/Mg2+ ions separation are proved to be 0.59 nm, 0.57 nm and 0.5 nm, respectively. Also, the permeation selectivity of K+/Mg2+, Na+/Mg2+ and Li+/Mg2+ are 676, 399 and 96, respectively. This strategy realizes the precise control of the channel height in the sub-nanometer scale and demonstrates the potential of MMT membranes for mono/divalent cations separation, providing a feasible and scalable pathway for developing high-performance 2D channel membranes.

1,2-bis(triethoxysilyl)methane (BTESM)-derived organic–inorganic membranes with controlled sol particle size: Preparation and pervaporation dehydration performance of isopropanol aqueous solutions

1,2-bis(triethoxysilyl)methane (BTESM) is a bridged-type organoalkoxysilane, which was utilized for organic–inorganic membranes preparation via a sol–gel method to achieve high permselectivity, thus are promising for dehydration and purification of organic solvents. However, the particle size of the derived sol is crucial for membrane preparation during sol–gel processing, significantly influencing the membrane’s performance. Herein, we reported a novel strategy of controlling the sol particle size by adjusting the pH during the preparation process. BTESM-derived membranes were prepared by BTESM-H+ sol and BTESM-swing sol, which were subsequently employed for the dehydration of isopropanol (IPA) through pervaporation (PV). Compared with the BTESM-H+ sol, the particle size of the BTESM-swing sol prepared by the pH-swing method was increased from 1.3 nm to 32.7 nm. The larger particle size could hinder the permeation into the intermediate layer. Meanwhile, the dense arrangement of silica particles could efficiently retain IPA molecules, thereby substantially enhancing the rejection rate of IPA. The average particle size of the BTESM-swing sol was 18.7 nm at an acid-base ratio of 1.2 and acid-silicon ratio of 0.55, resulting a permeate flux of 1.04 kg·m−2·h−1 and separation factor of 521, while IPA rejection rate was 97.84 %. This work has shown that adjusting the pH during the process is a useful strategy of controlling the sol size for the preparation of organic–inorganic membranes. Hence, the control of sol particle size to achieve a high-performing membrane layer offers a novel approach to producing diverse membrane materials.

Construction of sub-10nm ultra-thin polyamide layer using porous GOQDs-AGQDs interlayer

The application of high-performance polyamide nanofiltration membranes with controllable structures shows promising prospects in fields such as seawater desalination and wastewater treatment. In this study, a high-performance polyamide composite nanofiltration membrane with sub-10nm ultra-thin separation layer was designed and fabricated using a hydrophilic porous GOQDs-AGQDs (graphene oxide quantum dots-amino graphene quantum dots) interlayer to reconstruct the substrate architecture. The GOQDs-AGQDs interlayer not only improved the uniformity and smoothness of the microporous substrate, but also could form hydrogen bond with amine monomers to effectively inhibit its diffusion, thereby effectively slowing down the interfacial polymerization process and facilitating the formation of an ultra-thin, smooth and dense polyamide (PA) layer. The results demonstrate that the optimized PA/GOQDs-AGQDs/PES membrane achieved a PA separation layer thickness as low as 9.4 nm, with a permeation flux of 27.2 L·m−2 ·h−1·bar−1, nearly three times that of the original PA/PES membrane. Simultaneously, it enhanced the Na2SO4 rejection rate to 97.1 %, achieving synchronous improvements in permeability and selectivity. Additionally, the PA/GOQDs-AGQDs/PES composite membrane exhibited relatively low surface roughness and demonstrated excellent long-term stability. This work presents a novel strategy for the controllable fabrication of high-performance nanofiltration membranes.

Bioinspired Homonuclear Diatomic Iron Active Site Regulation for Efficient Antifouling Osmotic Energy Conversion.

Membrane-based reverse electrodialysis is globally recognized as a promising technology for harnessing osmotic energy. However, its practical application is greatly restricted by the poor anti-fouling ability of existing membrane materials. Inspired by the structural and functional models of natural cytochrome c oxidases (CcO), the first use of atomically precise homonuclear diatomic iron composites as high-performance osmotic energy conversion membranes with excellent anti-fouling ability is demonstrated. Through rational tuning of the atomic configuration of the diatomic iron sites, the oxidase-like activity can be precisely tailored, leading to the augmentation of ion throughput and anti-fouling capacity. Composite membranes featuring direct Fe-Fe motif configurations embedded within cellulose nanofibers (CNF/Fe-DACs-P) surpass state-of-the-art CNF-based membranes with power densities of ca. 6.7Wm-2 and a 44.5-fold enhancement in antimicrobial performance. Combined, experimental characterization and density functional theory simulations reveal that homonuclear diatomic iron sites with metal-metal interactions can achieve ideally balanced adsorption and desorption of intermediates, thus realizing superior oxidase-like activity, enhanced ionic flux, and excellent antibacterial activity.

Concentric circular flow field to improve mass transport in large-scale proton exchange membrane water electrolysis cells

Uniform reactant supply is challenging for high-performance proton exchange membrane water electrolysis (PEMWE) in renewable energy storage. The anode flow-field pattern, anode flow-field orientation, and stoichiometric ratio influence mass transport. In this study, the performances of two flow-field patterns were compared for a single PEMWE cell with an active area of 100 cm2. Straight serpentine was used as the reference model and a concentric circle with an arc shape was designed. In addition, the optimal anode flow field orientation and stoichiometric ratio were determined. The results indicate that the optimal anode flow-field pattern differs depending on the stoichiometric ratio. At low flow rates, mass transfer via diffusion was dominant; therefore, a straight serpentine flow was preferred. In contrast, a concentric circle, which induces a significant differential pressure between adjacent channels, is preferable at a high flow rate. This is because convection is dominant in mass transfer. Maintaining a stoichiometric ratio of 10 or more is recommended during the operation. At a ratio of less than 10, the reactant was depleted at a high current density, and the mass transfer resistance increased. In addition, water is better distributed by gravity and buoyancy when the electrolyte membrane is parallel to the ground, and the anode flow path is above the porous medium. This leads to high PEMWE cell performance.

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.