Ultrahigh Flux Research Articles

Nickel-cobalt hydrogen phosphate membrane with outstanding anti-crude oil-fouling capability and its microscopic anti-fouling mechanism

Oil/water separation membranes with superior anti-fouling properties against highly viscous oils are crucial for the efficient treatment of oily wastewater. Herein, the effects of functional groups in an inorganic superhydrophilic membrane on the anti-fouling properties of the membrane are investigated. Using a facile one-step electrochemical deposition method, Ni1-xCoxHPO4·3H2O membranes were formed on a Cu(OH)2 microneedle-coated copper mesh (CCNC–P) with superhydrophilic and underwater superoleophobic properties. All CCNC–P membranes with different Co2+ contents showed outstanding anti-fouling capability for oily wastewater such as those containing crude oil. The CCNC–P(x = 0.5) membrane exhibited high separation efficiency reaching 99.7 % across five oil–water mixtures and oil-in-water emulsions, concurrently presenting an ultrahigh flux of 61695 L m−2 h−1 for crude oil–water mixture. Moreover, the membrane consistently maintained its separation performance during the long-term crude oil–water separation process. The flux decline ratio was below 1 %, and the flux recovery ratio approached 99.4 %. The CCNC–P membranes possessed superior chemical, thermal, and mechanical stability, suggesting significant potential for the industrial treatment of oily wastewater. Density functional theory calculation revealed that the HPO42− group in CCNC–P can strongly adsorb water molecules. The resultant stabilized hydration layer impeded the contact between the membrane surface and oil droplets, while the metal ions scarcely influenced the adsorption of water molecules on CCNC–P. These findings provide new insights into the development of novel oil–water separation membranes with higher anti-fouling capabilities against high-viscosity oils.

Ultra-high charge electron acceleration for nuclear applications

Ultra-intense laser-plasma wakefield accelerator possess several superior properties compared with the traditional radio-frequency accelerators. These characteristics include femtosecond duration, micro-source size, and ultra-dense beam density, result in highly advantageous for various important applications. In this paper, we reviewed the generation of ultra-intense and high charge electron beam based on laser-plasma acceleration and its nuclear applications in Shanghai Jiao Tong University, including the production of 10 s nC charge beams, the generation of ultra-high flux neutron source on the order of 1019 n/cm2/s, and the excitation of nuclear isomers with the peak efficiency on the order of 1015 particle/s. This laser driving ultra-dense electron source, in conjunction with the plasma environment, presents immense potential in addressing critical problems in astrophysics, and facilitating various nuclear applications. Based on above progress in nuclear astrophysics, a new research plateform about laboratory astrophysics with a 2.5 PW laser will be constructed in TDLI institute.

Vertically Grown Bioinspired Diphenylalanine Nanowire-Coated Fabric for Oil-Water Separation.

Due to the pervasive use of oil for energy and other industrial applications, solutions to oil-water separation have received a great deal of attention lately to address the environmental damage of oil spills and groundwater contamination. However, many of these separation methods are materially expensive and environmentally hazardous, require elaborate fabrication, or rely on large amounts of energy to function. Herein, we provide an effective low-cost method for oil-water separation based on the hydrophobicity induced by self-assembled bioinspired diphenylalanine peptide nanowires grown on polyester fabric. This modified polyester fabric mesh exhibits parahydrophobicity and oleophilicity due to the hierarchical nano-to-microscale surface roughness. This mesh also achieves consistent high water separation efficiencies of over 99% and an ultrahigh oil flux of up to 26.7 ± 5 kLm-2·h-1. The growth of bioinspired peptide-based nanostructures on fabrics using facile technique and their application in oil-water separation presents the potential for using bioinspired materials for environmental remediation while minimizing environmental footprint.

Rough and porous silica-modified fiber membranes decorated with oleic acid for ultra-high flux and pH-responsive oil/water separation

The design of fiber membranes with both ultra-high flux and pH-responsive oil/water separation is challenging but of great significance to environmental protection and human health. In this work, the pH-responsive fiber membranes were prepared by immersing the silica-modified polyacrylonitrile fiber substrates into oleic acid solution. The obtained membranes exhibited highly rough surface structures (Ra = 14.26 µm), large pore sizes (5.35 µm), high porosities (86.04%), and pH-responsive functional groups, respectively. The pH-responsive fiber membranes also had superhydrophobic surfaces and excellent selective separation for oil/water mixtures, for example, a trichloromethane permeation flux of 87,829 L m-2h-1 for immiscible oil/water separation, and a water permeation flux of 69,802 L m-2h-1 after turning the pH of water from 7 to 13. The above data were much higher than those of stimulus-responsive fiber membranes used for oil/water separation. In addition, the pH-responsive fiber membranes were also used for separating water-in-oil emulsions and oil-in-water emulsions, and achieved the highest separation flux of 15,120 L m-2h-1. This work provides a simple strategy for the preparation of a stimulus responsiveness and high-performance material that can be used in the direction of treating practical oily wastewater.

Performance improvement of reflective phosphor film via adjusting the thickness realizing bright and efficient laser lighting.

Phosphor-in-glass-film (PiG-F) has been extensively investigated, showing great potential for use in laser lighting technique. Thickness is apparently a key parameter for PiG-F, affecting the heat dissipation, absorption, and reabsorption, thus determining the luminous efficacy and luminescence saturation threshold (LST). Conventional studies suggest that thinner films often have lower thermal load than that of the thicker ones. Unexpectedly, we found that the Lu3Al5O12:Ce (LuAG:Ce)-based PiG-F with a moderate thickness (78 μm) yielded the optimal LST of 31.9 W (14.2 W·mm-2, rather than 28.0 W (12.3 W·mm-2) for the thinnest one (56 μm). This unexpected result was further verified by thermal simulations. With the high saturation threshold together with a high luminous efficacy (∼296 lm·W-1), an ultrahigh luminous flux of 7178 lm with a luminous exitance of 2930 lm·mm-2 was thus attained. We believe the new, to the best of our knowledge, findings in this study will substantially impact the design principles of phosphors for laser lighting.

Ultra-high flux loose nanofiltration membrane based on metal organic framework (CAU-10-H)/P84 co-polyimide for dye/salt fractionation from industrial waste water

In recent times, loose nanofiltration (NF) membranes have gained popularity for the treatment of dye/salt industrial wastewater, primarily owing to their exceptional separation capabilities and economic advantages. However, achieving nanocomposite mixed matrix membranes with ultrahigh water permeance and specific pore and surface characteristics for effective dye and inorganic salt fractionation presents a significant challenge. This study focuses on the development of high-efficiency loose nanofiltration mixed matrix membranes (MMMs) achieved by combining polymers and porous nanoparticles. Metal-organic frameworks (MOFs) hold substantial promise as porous additives in MMMs. However, high-quality MOF-based MMMs for treating dye/salt aqueous solutions are still scarce. In this work, we synthesized an aluminum-based metal-organic framework (CAU-10-H) and utilized it in the fabrication of composite MMMs by blending it with co-polyimide (P84). We successfully created a thin and porous CAU-10-H/P84 layer with a significantly low MOF content (1.5 %) on a nylon support. Our research findings revealed that the optimized membrane exhibited desirable permeance (260.4 LMH/bar) for dye/salt solutions and a pure water permeance of 386.4 LMH/bar. Furthermore, the membrane demonstrated high dye rejection (99.2 % for methyl blue and 99.1 % for Congo red) while maintaining low salt rejection (4.8 % for NaCl and 16.3 % for Na2SO4). Additionally, the composite MMMs exhibited excellent stability throughout a 24-h filtration process. The CAU-10-H/P84 composite MMMs exhibit significant potential for applications in dye/salt fractionation.

Fabrication of hollow electrospun Polypyrrole@Cellulose fibrous membrane for ultrahigh-flux dye removal

Membrane technology is a promising method for wastewater treatment, and the balancing between high water flux and high rejection is crucial but extremely challengeable. Herein, an advanced polypyrrole@cellulose fibrous membrane with a hollow structure was prepared through electrospinning followed by a dip-coating process. The sustainable and low-cost cellulose was applied as the raw material while the nontoxic and environmentally stable polypyrrole was chosen as the active layer. Benefiting from the unique hollow structure and the abundant adsorption sites from the polypyrrole, the resulting membrane achieved 99.4 % rejection of anionic Congo red, along with a water flux of 3025.5 L m−2 h−1, which was 4–140 times higher than that of the previously reported membranes. Moreover, it could also efficiently separate cationic methylene blue (a rejection ratio of >96.0 %). This work confirmed the feasibility of hollow electrospun membrane with high dye rejection at ultrahigh water flux, and offered new possibilities to overcome the conflicts between permeation and selectivity in dyeing wastewater treatment.

Stable and Durable Superhydrophobic Cotton Fabrics Prepared via a Simple 1,4-Conjugate Addition Reaction for Ultrahigh Efficient Oil-Water Separation.

Superhydrophobic materials used for oil-water separation have received wide attention. However, the simple and low-cost strategy for making durable superhydrophobic materials remains a major challenge. Here, this work reports that stable and durable superhydrophobic cotton fabrics can be prepared using a simple two-step impregnation process. Silica nanoparticles are surface modified by hydrolysis condensation of 3-aminopropyltrimethoxysilane (APTMS). 1,4-conjugate addition reaction between the acrylic group of cross-linking agent pentaerythritol triacrylate (PETA) and the amino group of octadecylamine (ODA) forms a covalent cross-linked rough network structure. The long hydrophobic chain of ODA makes the cotton fabric exhibit excellent superhydrophobic properties, and the water contact angle (WCA) of the fabric surface reaches 158°. The modified cotton fabric has good physical and chemical stability, self-cleaning, and anti-fouling. At the same time, the modified fabric shows excellent oil/water separation efficiency (98.16% after 20 cycles) and ultrahigh separation flux (15413.63 L m-2 h-1) due to its superhydrophobicity, superoleophilicity, and inherent porous structure. The method provides a broad prospect in the future diversification applications of oil/water separation and oil spill cleaning.

Pilot-scale performance of gravity-driven ultra-high flux fabric membrane systems for removing small-sized microplastics in wastewater treatment plant effluents

The ubiquitous nature and environmental impacts of microplastic particles and fibers demand effective solutions to remove such micropollutants from sizable point sources, including wastewater treatment plants and road runoff facilities. While advanced methods, e.g., microfiltration and ultrafiltration, have shown high removal efficiencies of small-sized microplastics (<150 μm), the low flux encountered in these systems implies high operation costs and makes them less effective in high-capacity wastewater facilities. The issue presents new opportunities for developing cheap high-flux membrane systems, deployable in low-to high-income economies, to remove small-sized microplastic and nanoplastics in wastewater. Here, we report on developing an ultra-high flux gravity-driven fabric membrane system, assessed through a laboratory-scale filtration and large-scale performance in an actual wastewater treatment plant (WWTP). The method followed a carefully designed water sampling, pre-treatment protocol, and analytical measurements involving Fourier transform infrared (FTIR) spectroscopy and laser direct infrared (LDIR) imaging. The result shows that the ultra-high flux (permeance = 550,000 L/m2h⋅bar) fabric membrane system can effectively remove small-sized microplastics (10–300 μm) in the secondary effluent of an actual WWTP at high efficiency greater than 96 %. The pilot system demonstrated a continuous treatment capacity of 300,000 L/day through a 1 m2 surface area disc, with steady removal rates of microplastics. These findings demonstrate the practical, cheap, and sustainable removal of small-sized microplastics in wastewater treatment plants, and their potential value for other large-scale point sources, e.g., stormwater treatment facilities.

Conjugated Microporous Polymers-Based Catalytic Membranes with Hierarchical Channels for High-Throughput Removal of Micropollutants.

Engineering a catalytic membrane capable of efficiently removing emerging organic microcontaminants under ultrahigh flux conditions is of significance for water purification. Herein, drawing inspiration from the functional attributes of lymphatic vessels involved in immunosurveillance and fluid transport with minimal energy consumption, a novel hierarchical porous catalytic membrane is engineered. This membrane, based on an innovative nitrogen-rich conjugated microporous polymer (polytripheneamine, PTPA), is synthesized using an electrospinning coupled in situ polymerization approach. The resulting bioinspired membrane with hierarchical channels comprises a thin layer (≈1.7µm) of crosslinked PTPA nanoparticles covering the interconnected electrospun nanofibers. This unique design creates an intrinsic microporous angstrom-confined system capable of activating peroxymonosulfate (PMS) to generate 98.7% singlet oxygen (1O2), enabling durable and highly efficient degradation of microcontaminants. Additionally, the presence of a thin layer of mesoporous structure between PTPA nanoparticles and macroporous channels within the interwoven nanofibers enhances mass transfer efficiency and facilitates high flux rates. Notably, the prepared hierarchical porous organic catalytic membrane demonstrates enduring high-efficiency degradation performance with a superior permeance (>95% and >2500 L m-2 h-1 bar-1) sustained over 100 h. This work introduces an innovative pathway for the design of high-performance catalytic membranes for the removal of emerging organic microcontaminants.

Superhydrophobic Bud Protrusion-Polypropylene Fiber Membrane with Ultrahigh Flux for Oil–Water Separation

Superhydrophobic Bud Protrusion-Polypropylene Fiber Membrane with Ultrahigh Flux for Oil–Water Separation

Ultra-efficient decontamination via functionalized reactive electrochemical membrane for peroxymonosulfate activation: High water flux with extremely low energy consumption

A perovskite LaCoO3 functionalized Ti4O7 reactive electrochemical membrane (REM) was developed for electro-enhanced peroxymonosulfate (PMS) activation (E-REM-PMS), addressing limitations in wastewater treatment efficiency, reusability, and interference resistance. It achieved 100% carbamazepine (CBZ) removal at a rate constant of 39.69 min−1, 233 and 23 times of electro-REM (E-REM) system without PMS and REM-PMS system without electricity. In-situ Fourier transform infrared spectroscopy (FTIR) highlighted the promotion of electro-activation on PMS, while density functional theory (DFT) calculations elucidated mechanism differences under three adsorption configurations. 1O2 (2.97×10−9 M), SO4•− (2.09×10−11 M) and •OH (7.36×10−12 M) dominated the E-REM-PMS system, consistent with sequence of reactive species by DFT results. Continuous treatment of pharmaceutical wastewater confirmed 100% CBZ removal and 60%-70% TOC mineralization at ultrahigh water flux (642.86 L/m2·h) with minimal energy consumption (0.01 kWh/m3·order). This work proposed a high-performance and anti-fouling REM, offering an efficient and economical solution for wastewater treatment.

Ion-Concentration-Hopping Heterolayer Gel for Ultrahigh Gradient Energy Conversion.

Conventional solid ion channel systems relying on single one- or two-dimensional confined nanochannels enabled selective and ultrafast convective ion transport. However, due to intrinsic solid channel stacking, these systems often face pore-pore polarization and ion concentration blockage, thereby restricting their efficiency in macroscale ion transport. Here, we constructed a soft heterolayer-gel system that integrated an ion-selective hydrogel layer with a water-barrier organogel layer, achieving ultrahigh cation selectivity and flux and effectively providing high-efficiency gradient energy conversion on a macroscale order of magnitude. Specifically, the hydrogel layer featured an unconfined 3D network, where the fluctuations of highly hydrated polyelectrolyte chains driven by thermal dynamics enhanced cation selectivity and mitigated transfer energy barriers. Such chain fluctuation mechanisms facilitated ion-cluster internal transmission, thereby enhancing ion concentration hopping for more efficient ion-selective transport. Compared to the existing rigid nanochannel-based gradient energy conversion systems, such a heterogel-based power generator exhibited a record power density of 192.90 and 1.07 W/m2 at the square micrometer scale and square centimeter scale, respectively (under a 500-fold artificial solution). We anticipate that such heterolayer gels would be a promising candidate for energy separation and storage applications.

In situ growth of ZIF-8 on nanofibrous membrane for long-term ultra-high flux coalescence separation of oil-in-water emulsion

The presence of oil-in-water (O/W) emulsions poses a serious threat to the equilibrium of aquatic ecosystems, contaminates potable water resources, and disrupts the structure of soil layers. Consequently, there is an urgent need for effective and economically viable methods for removing emulsified oil droplets from water. The coalescence method has been proposed as an effective means of separating O/W emulsions. In this study, we developed an in situ growth strategy to decorate zeolitic imidazolate framework-8 (ZIF-8) on electrospun polyacrylonitrile (PAN) nanofibers for coalescence separation. The in situ growth process commenced with pretreatment to activate the PAN membrane, creating anchor sites for zinc ions, which was followed by immersion in precursors of ZIF-8 particles. The incorporation of ZIF-8 enhanced amphiphilicity, and roughness, and imparted a positive charge to the membrane, which was anticipated to effectively demulsify and coalesce oil droplets with a negative charge. The ZIF-8/PAN nanofiber membrane obtained a separation ratio exceeding 99.9 % for surfactant-free emulsions and 97.1 % for surfactant-stabilized emulsions. It also demonstrated an ultra-high permeation flux of 21,177 L m−2 h−1 and 14,118 L m−2 h−1, respectively, in a long-term continuous separation process.

An efficient solution based on the synergistic effects of nickel foam in NiFe-LDH nanosheets for oil/water separation

Efficient oil-water separation has always been a research hotspot in the field of environmental studies. Employing a one-step hydrothermal approach, NiFe-layered double hydroxides (LDH) nanosheets were synthesized on nickel foam substrates. The resulting NiFe-LDH/NF membrane exhibited rejection rates exceeding 99% across six diverse oil-water mixtures, concurrently demonstrating a remarkable ultra-high flux of 1.4 × 106 L·m−2·h−1. This flux value significantly surpasses those documented in existing literature, maintaining stable performance over 1000 manual filtration cycles. These breakthroughs stem from the synergistic interplay among the three-dimensional channels of the nickel foam, the nanosheets, and the hydration layer. By leveraging the pore size of the foam to enhance the functionality of the hydration layer, the conventional trade-off between permeability and selectivity was transformed into a balanced force relationship between the hydration layer and the oil phase. The operational and failure mechanisms of the hydration layer were examined using the prepared NiFe-LDH/NF membrane, validating the correlation between oil phase viscosity and density with hydration layer rupture. Additionally, an extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was employed to investigate changes in interaction energy, further reinforcing the study's findings. This research contributes novel insights and assistance to the comprehension and application of hydration layers in other membrane studies dedicated to oil-water separation.

Alkaline-oxidized MXene composite membrane of ultra high flux and advanced rejection performance for water purification

MXene is a metal-carbon/nitrogen compound material with a two-dimensional layered structure. As a new form of two-dimensional material, it has great potential in the field of water purification because of its properties of high permeability and hydrophilicity. In this study, a MXene composite membrane was prepared by in-situ oxidation of titanium dioxide on the MXene surface by an alkaline oxidation method. A series of characterizations of the prepared MXene composite membrane was carried out. Scanning electron microscopy showed that with an increasing degree of oxidation, the extent of agglomeration of MXene nanosheets increased, thus generating more water channels that are conducive to the transport of water molecules, and an increasing water flux. The penetration performance, interception performance, and stability of the MXene composite membrane were tested. The effect of different concentrations of KOH on the properties of the composite membrane was investigated. It was found that the flux of the composite membrane increased with alkali concentration by 4.6–28.8 times the flux without exposure to alkali. It was found that the rejection rate of the composite membrane for pollutants (dyes, humic acid, bovine serum albumin protein) decreased only slightly with increasing alkali concentration, and was ≥94% of the pure MXene membrane rejection rate in all cases. The rejection performance of the composite membrane was related to the size and charge properties of the pollutant molecules. The results of the stability tests showed that the composite membranes had a high degree of physical and flux stability in a range of aqueous solutions.

A mild one-step method to fabricate graphene oxide cross-linked with dopamine/polyethyleneimine (GO@DA/PEI) composite membranes with an ultrahigh flux for heavy metal ion removal

Heavy metal ion contamination poses a significant threat to both our environment and human health. Consequently, there is a need for proficient and environmentally friendly remediation techniques to tackle this issue. Among various strategies, membrane-based separation using graphene oxide (GO) laminate membranes has emerged as a promising solution. However, traditional GO membranes have low water permeance, poor selectivity, structural instability, and inconsistent layer spacing. In this study, we cross-linked GO with polydopamine/polyethyleneimine (DA/PEI) using a mild one-step strategy to prepare a GO@DA/PEI membrane for heavy metal ion removal and evaluated the effect of cross-linking duration on the interlayer structure, membrane properties, and heavy metal ion removal performance. The successful formation of a cross-linked network between DA/PEI and GO was proven by various characterization methods. Compared with previously reported GO-based membranes, the prepared GO@DA/PEI40 membrane exhibited excellent performance, including a peak pure water flux of 326.7 L/m2h and ion rejection of 99.6 % for Cu2+, 93.5 % for Pb2+, and 96.6 % for Zn2+, thereby overcoming the conventional trade-off” effect. The mechanism for the high flux was discussed. The cross-linking reaction between the oxygen-containing functional groups at the edges and basal planes of the GO flakes and DA/PEI were crucial to the high flux. In addition, the GO@DA/PEI40 membrane had excellent anti-fouling performance in the presence of humic acid and long-term stability under different conditions. Overall, the GO@DA/PEI membrane has good potential for heavy metal ion removal.

Study on flow and heat transfer characteristics of liquid metal flow in narrow rectangular channels under high heat flux

In order to improve the core power density of liquid metal reactors, narrow rectangular fuel assemblies are typically used, which have obvious advantages in heat transfer capacity. However, the flow and heat transfer characteristics in coolant passage need to be studied. In this article, the numerical simulation analysis model obtained earlier was applied to calculate the Nusselt number, friction factor, with different Reynolds number, Prandtl number, or Peclet number of lead bismuth flow in a narrow rectangular channel under high heat flux. A heating correction factor was proposed and a flow resistance model was established for high heat flux. The influencing factors of ultra-high flux reactor core, such as gap size, flow direction, single and double sided heating conditions, on the flow and heat transfer in narrow rectangular channels were explored. The results showed that gap size and aspect ratio have a certain impact on the Nu and f of narrow rectangular channels, but the influence is relatively small within the narrow rectangular channel condition range. The influence of flow direction on flow and heat transfer is minimal, the single and double sided heating conditions will bring about a difference of about 20% in Nu and a difference of about 2.5% in f. In addition, the type of liquid metal will also affect the results. The research can provide reference for the thermal design and optimization of ultra-high flux reactor cores.

Ultra-high flux mesh membranes coated with tannic acid-ZIF-8@MXene composites for efficient oil-water separation

Oil/water separation has become a global concern due to the increasing discharge of multi-component harmful oily wastewater. Super wetting membranes have been shown to be an effective material for oil/water separation. Ultra-high flux stainless-steel meshes (SSM) with superhydrophilicity and underwater superoleophobicity were fabricated by tannic acid (TA) modified ZIF-8 nanoparticles (TZIF-8) and two-dimensional MXene materials for oil/water separation. The TZIF-8 increased the interlayer space of MXene, enhancing the flux permeation (69,093 L m−2h−1) and rejection of the composite membrane (TZIF-8@MXene/SSM). The TZIF-8@MXene/SSM membrane showed an underwater oil contact angle of 154.2°. The membrane maintained underwater superoleophobic after stability and durability tests, including various pH solutions, organic solvents, reusability, etc. In addition, the oil/water separation efficiency of TZIF-8@MXene/SSM membranes was higher than 99% after treatment in harsh conditions and recycling. The outstanding anti-fouling, stability, durability, and recyclability properties of TZIF-8@MXene/SSM membrane highlight the remarkable potential of membranes for complex oil/water separation process.

Alkadiyne-Pyrene Conjugated Frameworks with Surface Exclusion Effect for Ultrafast Seawater Desalination.

Billions of populations are suffering from the supply-demand imbalance of clean water, resulting in a global sustainability crisis. Membrane desalination is a promising method to produce fresh water from saline waters. However, conventional membranes often encounter challenges related to low water permeation, negatively impacting energy efficiency and water productivity. Herein, we achieve ultrafast desalination over the newly developed alkadiyne-pyrene conjugated frameworks membrane supported on a porous copper hollow fiber. With membrane distillation, the membrane exhibits nearly complete NaCl rejection (>99.9%) and ultrahigh fluxes (∼500 L m-2 h-1) from the seawater salinity-level NaCl solutions, which surpass the commercial polymeric membranes with at least 1 order of magnitude higher permeability. Experimental and theoretical investigations suggest that the large aspect ratio of membrane pores and the high evaporation area contribute to the high flux, and the graphene-like hydrophobic surface of conjugated frameworks exhibits complete salt exclusion. The simulations also confirm that the intraplanar pores of frameworks are impermeable for water and ions.