High-performance Composite Membranes Research Articles

Cobalt-Based ZIF Composite Membranes: In Situ Defect Engineering for Enhanced Water Stability and Gas Separation.

Porous coordination polymers with excellent molecular sieving ability, high dispersibility, and good compatibility with engineered polymer matrices hold promise for various industrial applications, such as gas separation and battery separators. Here, an in situ defect engineering approach is proposed for highly processable cobalt (Co)-based zeolitic imidazolate frameworks (ZIFs) with enhanced molecular sieving ability and water stability. By varying alkylamine (AA)modulators, the pore structures and textural properties of ZIFs can be fine-tuned. The resulting high-loading composite membrane exhibits excellent C3H6/C3H8 separation performance and mechanical properties. This in situ defect engineering approach enables efficient interfacial engineering for high-performance composite membranes.

High-performance calcium alginate hydrogel composite nanofiltration membrane for dyeing wastewater separation

High-performance calcium alginate hydrogel composite nanofiltration membrane for dyeing wastewater separation

BNT Scaffold Contributes to High-Performance Piezoelectric Composite Membranes for Self-Powered Flexible Pressure Sensors

BNT Scaffold Contributes to High-Performance Piezoelectric Composite Membranes for Self-Powered Flexible Pressure Sensors

High-performance polyester composite nanofiltration membrane fabricated by interfacial polymerization of ribitol and trimesoyl chloride: Dye desalination performance and mechanisms

A loose nanofiltration (LNF) membrane with high permeance and excellent dye/salt selectivity is highly desirable for dye/salts recovery from textile wastewater. Herein, commercial and green ribitol (RT) was employed to fabricate the LNF membrane for dye desalination. The hydroxyl in the RT reacted with acyl chloride under the catalysis of sodium hydroxide, forming a polyester film structured with microspheres, negative charge, and hydrophilic networks. The resultant RT-M membrane possessed a smooth and thin active layer with numerous polar groups. The dye desalination performance of the RT-M membrane was tailored by controlling various IP fabrication conditions. The optimized membrane (RT-M1.0) had superior water permeance (100.3 L m−2h−1 bar−1) and satisfactory CR/Na2SO4 selectivity (281.3). Additionally, the RT-M membrane had favorable stability and antifouling properties, demonstrating excellent potential for application in dye desalination. Therefore, a novel approach for fabricating membranes with outstanding dye desalination properties by using RT was proposed to achieve resource recycling.

A High-Performance Polyimide Composite Membrane with Flexible Polyphosphazene Derivatives for Vanadium Redox Flow Battery.

A sulfonated polyimide, S-F-abSPI, with alkyl sulfonic acid side chains, and a polyphosphonitrile derivative, poly[4-methoxyphenoxy (4-fluorophenoxy) phosphazene] (PFMPP), were designed and synthesized. Composite modification of the S-F-abSPI membrane was carried out using PFMPP, resulting in the preparation of composite membranes with different composite ratios, which were then subjected to performance testing and characterization. Experimental results revealed a significant enhancement in the proton conductivity of the S-F-abSPI membrane, reaching 0.116 S cm-1, slightly higher than that of the N212 membrane. The S-F-abSPI/1% PFMPP composite membrane exhibited the optimal comprehensive performance, with a surface resistance as low as 0.54 Ω cm2, comparable to that of the N212 membrane. At a high current density of 200 mA cm-2 during charge-discharge, the composite membrane achieved a voltage efficiency (VE) of 83.12% and an energy efficiency (EE) of 81.95%. Cycling tests over 200 cycles demonstrated the composite membrane's excellent long-term cycling stability. The alkyl sulfonic acid side chains enhanced the proton conductivity of the membrane, while electrostatic potential distribution calculations indicated strong interactions between PFMPP and the base membrane, enhancing the membrane's mechanical strength, reducing vanadium ion permeability, and improving chemical stability and vanadium ion selectivity. This composite membrane holds promise for high-performance VRFB applications.

High performance composite hollow fiber nanofiltration membrane fabricated via the synergistic effect of co-solvent assisted interfacial polymerization and macrocyclic polyamine incorporation

The necessity for high-performance thin film composite (TFC) nanofiltration (NF) membranes for drinking water and wastewater treatment is becoming increasingly apparent in the face of the global water crisis. In this work, co-solvent (acetone) assisted interfacial polymerization (CAIP) and incorporating macrocyclic polyamine (Cyclen) as an aqueous co-monomer were employed to fabricate hollow fiber (HF) NF membrane and to enhance the permeability and the selectivity, respectively, thereby overcoming the inherent trade-off effect. The effects of Cyclen and acetone on the separation performance were comprehensively investigated, and the interfacial polymerization conditions were optimized. The optimal HF NF membrane exhibits a 68.6 % increment in water permeance relative to the baseline membrane while without sacrificing the Na2SO4 rejection which is as high as 99.2 %. In particular, it exhibits a superior high pure water permeability of 222.5 L m−2 h−1 MPa−1, ranking among the highest observed for HF NF membranes in the existing literature. Moreover, it exhibits excellent acid resistance as well as fouling resistance. This research paves a novel approach for developing high-performance HF NF membranes for water and wastewater treatment.

High-Performance Composite Membranes: Embedding Yttria-Stabilized Zirconia in Polyphenylene Sulfide Fabric for Enhanced Alkaline Water Electrolysis Efficiency.

Due to their excellent alkali resistance and chemical stability, polyphenylene sulfide (PPS) fabric membranes are widely used in alkaline water electrolysis (AWE) for hydrogen production. However, traditional PPS membranes suffer from poor hydrophilicity, low airtightness, and high area resistance, resulting in high energy consumption and reduced safety in industrial applications. This study addresses the aforementioned issues by coupling 3-(2,3-epoxy propoxy) propyl trimethoxy silane (KH560) via self-condensation to the PPS membrane and blending it with self-synthesized yttrium-stabilized zirconia nanoparticles (YSZNPs). The YSZNPs are loaded onto the modified PPS fiber surface through dip-coating and hot-pressing processes, forming a micro-mechanical interlocking structure that enhances the overall performance of the membrane in practical hydrogen production applications. The findings indicate that the developed composite membrane demonstrate outstanding hydrophilicity, minimal area resistance (0.21 Ω cm2), and elevated bubble point pressure (2.93224bar). Significantly, tests on gas purity indicate that the produced hydrogen and oxygen attain purities of 99.90% and 99.75%, respectively, when evaluated at a current density of 1.5 A cm-2. Moreover, after 500h of electrolysis testing in a simulated industrial environment, minimal decline in membrane performance is observed, highlighting the competitive edge of this composite membrane in the current AWE market.

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.

High-performance COFs composite nanofiltration membrane fabricated by organobase catalyst

Covalent Organic Frameworks (COFs) composite nanofiltration (NF) membrane has high permeation flux and rejection. However, the reaction rate of COFs is relatively slow. Adding acid catalyst is a common method to shorten reaction time. However, the dissatisfactory synthesis rate will lead to irregular structure of COFs materials. In this work, it is the first time to use organobase as a catalyst to prepare COFs composite membrane. The COFs structure will be optimized and the membrane performance can be enhanced. The prepared TpPa-PIP membrane compared with acid catalyzed TpPa-HAc membrane has better permeability, permeance of 89 L m−2·h−1·bar−1 and CR rejection of 99.54 %. This improvement is because of the TpPa-PIP intermediate made slower reaction speed that improves the overall regularity and crystallinity of COFs. Therefore, it is better method for broadening the application of organobase-catalyzed in preparing membranes.

Fabrication of high-performance pervaporation desalination composite membranes with study of its acid-base stability

In the process of industrial production will produce a lot of acid and alkaline waste liquid, how to effectively treat acid and alkali waste liquid is an important topic at present. At present, there are some problems about the treatment of acid and alkali waste liquid, such as large investment, complicated process and low efficiency. Pervaporation has the characteristics of mild operating conditions and no influence of osmotic pressure threshold, so it has great application potential in the concentration, reuse and reduction of acid and alkali waste liquid. However, at present, conventional pervaporation dense membrane materials cannot maintain long-term stability in strong acid and alkali environment, in order to achieve this performance, we use perfluorosulfonic acid resin with good acid and alkali resistance as the dense layer substrate. PFSA/PTFE/PP composite membrane was prepared by spraying process, and the final prepared composite membrane had a pure water flux of 45 ± 1.2 kg/(m2∙h) at 70 ℃. The acid and alkali resistance of the intrinsic membrane and the composite membrane was evaluated, and it was found that the feed liquid was concentrated to 20 wt% after 19 h long concentration operation at 70℃ and starting liquid was 5 wt% H2SO4 and 5 wt% NaOH. The retention rate of acid and alkali can be maintained above 99.9 %. During the concentration of H2SO4 solution, the dense layer structure is affected, and the pure water flux of the composite membrane is reduced, eventually maintaining around 32 kg/(m2∙h). In the process of concentrating NaOH solution, the pure water flux of the composite membrane increased first and then decreased, and the final pure water flux of the membrane remained near 40 kg/(m2∙h).

High-performance polybenzimidazole composite membranes doped with nitrogen-rich porous nanosheets for high-temperature fuel cells

Traditional phosphoric acid (PA) doped polybenzimidazole (PBI) membranes encounter many issues when used in high-temperature proton exchange membrane fuel cell (HT-PEMFC), including the loss of PA within the membrane and limitations on conductivity. The mixed matrix membranes (MMMs) synergistically combine the advantages of pore fillers and polymer matrix, making them promising candidates for HT-PEMs. Interface compatibility is the main factor affecting the further development of MMMs. This research presented OPBI composite membranes filled with porous nanosheets, featuring average pore diameters of 2.83 nm, 3.38 nm, and 2.60 nm, respectively. The high aspect ratio and plentiful nitrogen components of the nanosheets increase the π-π and hydrogen bonding interactions with the polymer matrix, resulting in outstanding interface compatibility and mechanical properties of MMMs. The results of theoretical calculations indicate that there is a stronger interaction energy between the nanosheets and PA molecules, and the abundant pore structure within the nanosheets facilitates the absorption of PA molecules, leading to the formation of a continuous PA network. Consequently, MMMs exhibited enhanced proton conductivity, as well as improved PA absorption and retention. Furthermore, the effect of pore size distribution of nanofillers on the performance of MMMs were investigated. Membranes composed of nanosheets with large pore size showed a higher conductivity of 176.7 mS cm−1 at 200 °C, leading to excellent performance and stability in assembled H2/O2 fuel cells. This work offers valuable insights into the design of MMMs and high-performance HT-PEMs.

High performance and robust durability proton conductive composite membranes containing CeO2-TiC incorporated sulfonated poly(arylene ether) for hydrogen fuel cells

Degradation of proton exchange membrane (PEM) due to free radicals often decreases the overall performance of proton exchange membrane fuel cells (PEMFC). The incorporation of antioxidative additives into the polymer matrix has been widely exploited to mitigate oxidative degradation but is still challenging. Herein, butylsulfonated poly(arylene ether)(SAFPAE) was synthesized by polycondensation followed by nucleophilic substitution and highly crystalline CeO2-TiC filler was prepared by simple hydrothermal process. SAFPAE alleviates the problematic characteristics of proton-exchange membranes (PEMs) whereas CeO2 scavenges free radicals and TiC improves tensile strength. Variable weight ratios of CeO2-TiC were blended into the SAFPAE matrix to study its physicochemical, and electrochemical properties. The random distribution of CeO2-TiC in the SAFPAE matrix enhanced thermal and mechanical strength and increased water absorption, ion exchange capacity, as well as proton conductivity. Specifically, SAFPAE/CeO2-TiC (1.0 wt%) exhibited a current output of 0.18 A cm−2 and a power output of 0.087 Wcm−2 at 20 % RH and 60°C. It also experienced a degradation of 0.145 mV h−1 over 1100 hours of operation. Under operating conditions of RH 20 % and 60°C, PEMFCs with SAFPAE/CeO2-TiC (1.0 wt%) membrane exhibited significantly improved performance and enhanced durability compared to PEMFCs with pure SAFPAE and without sacrificing their cell performance.

Facile fabrication of PEDOT/PVDF composite membrane by vapor phase polymerization with excellent separation performance

The facile fabrication of high-performance polymer composite membranes poses a challenging task. Herein, poly (3, 4-ethylenedioxythiophene) (PEDOT) selective layer was deposited onto the surface of porous polyvinylidene fluoride (PVDF) substrate by a simple vapor phase polymerization (VPP) method, resulting in the fabrication of high-performance composite separation membrane PEDOT/PVDF. This composite membrane has excellent separation performance to separate model wastes in water systems. For instance, the rejection rates for differently charged neutral red (NR), azure Ⅱ (Azu Ⅱ), congo red (CR), and methylene blue (MB) were 99.1 ± 0.2 %, 99.2 ± 0.2 %, 99.4 ± 1.5 %, and 97.9 ± 1.0 %, respectively, with corresponding permeances of 42.3 ± 2.4 L m−2 h−1 bar−1, 60.1 ± 1.9 L m−2 h−1 bar−1, 25.1 ± 5.6 L m−2 h−1 bar−1, and 68.2 ± 4.9 L m−2 h−1 bar−1. PEDOT/PVDF composite membrane demonstrated excellent chemical stability, and the rejection rate of NR decreased by only 4.1 % during 48 h of continuous filtration. In the environment of NR solution (50 ppm) at 60 °C or Azu Ⅱ-NaOH solution (pH 13), it maintained high selectivity (>96 %) while significantly improving permeability (>80 L m−2 h−1 bar−1). The entire fabrication process of high-performance PEDOT/PVDF membrane was conducted at room temperature, with high versatility simple operation and minimal equipment requirement, offering significant advantage compared to similar reported membrane materials. This work provides a useful reference for the facile fabrication of high-performance separation membranes.

Construction of TiO2-ZrO2 composite nanofiltration membranes for efficient selective separation of dyes and salts

The ceramic nanofiltration (NF) membrane exhibits excellent potential for textile wastewater treatment due to its efficient selective separation of dyes and salts. In this study, a high-performance TiO2-ZrO2 composite nanofiltration membrane was fabricated via a sol–gel method. Stable sols with an average particle size of approximately 2 nm were obtained. The addition of TiO2 effectively inhibits the phase transformation of ZrO2 during heat treatment, thus improving the integrity and ensuring separation accuracy of the membrane. Moreover, an optimal balance between membrane integrity and thickness was achieved, promoting efficient selectivity towards dyes and salts. The optimized NF membrane exhibited a MWCO of 1 kDa, a membrane thickness of 100 nm, and pure water permeance of 44 L∙m−2∙h−1∙bar−1. Additionally, the NF membrane demonstrated exceptional performance in dye/salt separation as evidenced by rejection rates exceeding 97.71% for Reactive Blue 19 while maintaining rejections below 5% for NaCl/Na2SO4 solutions. A stable permeance of 21.65 L∙m−2∙h−1∙bar−1 was achieved during the separation process. In conclusion, this study presents a high-performance ceramic NF membrane which exhibits significant potential for treating dye/salt containing wastewater.

Construction of PDMS@ZIF-8 composite membrane on PVDF hollow fiber inner surface for ultrafast ethanol/water separation

Construction of ultra-thin and defect-free separation membrane on inner surface of hollow fiber supports is significant but challenging for molecular separation. In this study, the highly permeable PDMS@ZIF-8/PVDF composite membranes were successfully fabricated upon the inner-surface of polyvinylidene fluoride (PVDF) hollow fiber membrane for pervaporation (PV) ethanol/water separation. The efficient preparation of hierarchical PDMS@ZIF-8/PVDF composite membranes benefited from the precise regulation of ZIF-8 layer through interfacial synthesis and sequential coating of PDMS matrix. The thickness of the PDMS layer was only 16 ± 2 nm, which admirably eliminated the non-selective defects in ZIF-8 layer. Owning to the optimal combination of MOF layer and ultra-thin polymer layer, the as-prepared membrane exhibited the excellent ethanol flux of 1.34 kg m−2 h−1 with an ethanol concentration in permeate of 31.3 wt% for separating 5 wt% ethanol aqueous solution at 40 °C. The separation performance of the resultant membrane was superior to that of the other ethanol selective PV membranes. These findings herein provided a new way for preparing high-performance hollow fiber composite membranes for PV separation.

Flexible Piezoelectric Sensor Based on Two-Dimensional Topological Network of PVDF/DA Composite Nanofiber Membrane

Owing to the robust scalability, ease of control and substantial industrial applications, the utilization of electrospinning technology to produce piezoelectric nanofiber materials demonstrates a significant potential in the development of wearable products including flexible wearable sensors. However, it is unfortunate that the attainment of high-performance piezoelectric materials through this method remains a challenging task. Herein, a high-performance composite nanofiber membrane with a coherent and uniformly dispersed two-dimensional network topology composed of polyvinylidene fluoride (PVDF)/dopamine (DA) nanofiber membranes and ultrafine PVDF/DA nanofibers was successfully fabricated by the electrospinning technique. Based on the evidence obtained from simulations, experimental and theoretical results, it was confirmed that the unique structure of the nanofiber membrane significantly enhances the piezoelectric performance. The present PVDF/DA composite nanofibers demonstrated a remarkable piezoelectric performance such as a wide response range (1.5–40 N), high sensitivity to weak forces (0–4 N, 7.29 V N−1), and outstanding operational durability. Furthermore, the potential application of the present PVDF/DA membrane as a flexible wearable sensor for monitoring human motion and subtle physiological signals has also been validated. This work not only introduces a novel strategy for the application of electrospun nanofibers in sensors but also provides new insights into high-performance piezoelectric materials.Graphical

High-performance SPEEK composite membrane with ultrahigh selectivity enabled by sulfonated PANI for vanadium flow battery

The sulfonated poly(ether ether ketone) (SPEEK) composite membranes (S/SPANI) are prepared by blending sulfonated polyaniline (SPANI), which was synthesized through a post-sulfonation method. With the SPANI contents varying from 1 to 4 wt%, the S/SPANI membranes exhibit excellent physicochemical properties and cell performance, and at loading 3 wt% SPANI, S/SPANI-3 presents a higher proton conductivity (43.3 mS cm−1) and superior ion selectivity (49 × 103 S min cm−3) against SPEEK and Nafion 212. Moreover, its outstanding coulombic efficiency (95.9–98.4%) and energy efficiency (EE: 80.4–70.2%) at the current density of 100–200 mA cm−2 demonstrate an optimized tradeoff of proton conductivity and vanadium ion permeability. The performance optimization guarantees enhanced durability for 600 cycles and stable EE (76%) at 150 mA cm−2, which originated from the acid-base interaction, synergistic proton network, and interconnected chain structure. So, this provides a facile method to develop high-performance membranes by introducing desirable controllable topological molecular chains to construct synergistic proton transportation networks.

Construction of a high-performance hollow fiber composite NF membrane via the simultaneous modification of substrate and selective layer

Hollow fiber composite (HFC) nanofiltration (NF) membrane demonstrates significant commercial potential profiting from its self-supporting characteristic, high packing density and strong fouling resistance. In this work, a high-performance HFC NF membrane was successfully developed through simultaneous modification of the substrate via alkaline hydrolysis and incorporation of iopamidol (IPD) into the selective layer. Alkaline hydrolysis enhanced the hydrophilicity of the polyacrylonitrile (PAN) substrate by converting –CN groups into –COOH, thereby sharply improving the success rate of HFC NF membrane fabrication. The addition of IPD into piperazine (PIP) solution effectively increased the water permeability of the HFC NF membrane without compromising its salt rejection. Specifically, the optimized membrane sample denoted as NF-0.15P + 0.5I with 0.5 w/v% IPD added demonstrated a 44 % increase in PWP from 21.8 L·m−2·h−1·bar−1 to 31.5 L·m−2·h−1·bar−1, while maintaining a Na2SO4 rejection over 96.8 %. This improvement can be attributed to the decreased selective layer thickness and reduced MWCO. Furthermore, the membrane exhibited exceptional dye/salt separation performance. This work represents a novel approach leading to the development of a HFC NF membrane suitable for dye/salt separation.

Synergistic Effect of Ti3C2Tx MXene Nanosheets and Tannic Acid-Fe3+ Network in Constructing High-Performance Hydrogel Composite Membrane for Photothermal Membrane Distillation.

Photothermal membrane distillation (PMD) has emerged as a promising and sustainable approach for seawater desalination and wastewater purification. However, the wide application of the technique is severely impeded by low freshwater production and membrane fouling/wetting issues. Herein, we developed an advanced hydrogel-engineered membrane with simultaneously enhanced photothermal conversion capacity and desired fouling and wetting resistance for PMD. By the synergies of photothermal Ti3C2Tx MXene nanosheets and the tannic acid-Fe3+ network in the hydrogel, the membrane was endowed with excellent surface self-heating ability, yielding the highest freshwater production rate (1.71 kg m-2 h-1) and photothermal efficiency among the fabricated hydrogel composite membranes under 1 sun irradiation. Meanwhile, the PMD membrane could robustly resist oil-induced fouling and surfactant-induced wetting, significantly extending the membrane lifespan in treating contaminated saline water. Furthermore, when desalinating real seawater, the membrane exhibited superior durability with a stable vapor flux and excellent ion rejection (e.g., 99.24% for boron) for 100 h.

LEGO® brick-inspired ultra-stable and rapid transport 2D membrane for fast water purification

Inspired by the modular homogenization and interlocking structure concepts of LEGO® bricks, we developed high-performance graphene oxide composite nanofiltration membranes using the subject–object recognition effect.