Cross-flow Mode Research Articles

Heterogeneous Covalent Organic Framework Membranes Mediated by Polycations for Efficient Ions Separation.

Precise ions sieving at angstrom-scale is gaining tremendous attention thanks to its significant impact at the water-energy nexus. Herein, a novel polycation-modulated interfacial polymerization (IP) strategy is developed to prepare a heterogeneously charged covalent organic frameworks (COFs) membrane. Cationic poly(diallyldimethylammonium chloride) (PDDA) regulates the growth and assembly of anionic COFs nanosheets, which thus provides a negative, smooth top surface and positive, rough bottom surface, indicating the presence of heterogeneously charged angstrom-scale channels through the membrane. Experiments and simulations are conducted to understand the facilitated ions transport behavior relative to specific interactions raised by heterogeneously charged channels and angstrom-scale steric hinderance as well, rendering the membrane with robust mono-/divalent cations sieving capabilities. The selectivity (61.6) of Li+ to Mg2+ in mixed saline under the continuous cross-flow filtration mode is superior to most of the reported nanofiltration membranes. This polycation-mediated interfacial polymerization strategy offers a compelling opportunity to develop versatile heterogeneously charged COF membranes for exquisite ion sieving.

Ultra-permeable silk-based polymeric membranes for vacuum-driven nanofiltration.

Nanofiltration (NF) membranes are commonly supplied in spiral-wound modules, resulting in numerous drawbacks for practical applications (e.g., high operating pressure/pressure drop/costs). Vacuum-driven NF could be a promising and low-cost alternative by utilizing simple components and operating under an ultra-low vacuum pressure (<1 bar). Nevertheless, existing commercial membranes are incapable of achieving practically relevant water flux in such a system. Herein, we fabricated a silk-based membrane with a crumpled and defect-free rejection layer, showing water permeance of 96.2 ± 10 L m-2 h-1 bar-1 and a Na2SO4 rejection of 96.0 ± 0.6% under cross-flow filtration mode. In a vacuum-driven system, the membrane demonstrates a water flux of 56.8 ± 7.1 L m-2 h-1 at a suction pressure of 0.9 bar and high removal rate against various contaminants. Through analysis, silk-based ultra-permeable membranes may offer close to 80% reduction in specific energy consumption and greenhouse gas emissions compared to a commercial benchmark, holding great promise for advancing a more energy-efficient and greener water treatment process and paving the avenue for practical application in real industrial settings.

Stabilization Mechanisms of Traveling Crossflow Mode in Hypersonic Swept Wing Flows

Momentum potential theory (MPT) is employed to establish a physics-based interpretation of the traveling crossflow mode and analyze the underlying stabilization mechanisms of associated control methods, such as wall cooling, wall suction, and grooves. The traveling crossflow mode over a swept wing with a Mach number of 6 is first solved using direct numerical simulations. The MPT decomposition illustrates the vortical nature of the traveling crossflow mode, with the vortical component having a higher magnitude than the acoustic and thermal components. The vortical source makes the greatest contribution to the mode instability, whereas the response of the source terms depends on the control method used. Wall cooling primarily impacts the thermal component, thus decreasing the thermal source and subsequently changing the vortical source. Wall suction influences the vortical component directly, and only the vortical source undergoes a small reduction. The acoustic and vortical components are sensitive to grooves. The compression waves induced by grooves are identified as the source of the stabilization effect.

Boundary layer stability on a rotating wind turbine blade section

Wall-resolved large eddy simulations of the flow on a rotating wind turbine blade section are conducted to study the rotation effects on laminar-turbulent transition on the suction surface. A chord Reynolds number of 1×105 and angles of attack (AoA) of 12.8°, 4.2°, and 1.2° are considered. Simulations with and without rotation are performed for each AoA. For AoA=12.8°, rotation increases the reverse flow from 7% of the free-stream velocity in the non-rotating case to 16% of it in the rotating case in the laminar separation bubble (LSB), triggering an oblique instability mechanism in the latter, leading to a faster breakdown to small-scale turbulence. However, rotation delays transition and reattachment in 3%–4% of the chord due to the acceleration of the boundary layer upstream of the LSB, which is subject to a strong adverse pressure gradient (APG), stabilizing Tollmien–Schlichting (TS) waves. Regarding AoA=4.2° and 1.2°, rotation slightly decelerates the attached boundary layer since the APG is very mild but accelerates the separated flow downstream, stabilizing Kelvin–Helmholtz (KH) modes. This mitigates the oblique instability mechanism and slows down the breakdown of KH vortices in the rotating case. In these cases, the transition location is little affected by rotation, possibly due to a rotation-independent absolute instability. Rotation also generates a spanwise tip-flow in the LSB for AoA=4.2° and 1.2°, which is highly unstable and triggers stationary and traveling crossflow modes. Nevertheless, the amplitudes of these modes remain too low to trigger transition.

Nonmodal linear stability analysis of hypersonic flow over an inclined cone

Nonmodal linear stability analysis results are presented for hypersonic flow over a cone at 6° angle of attack complementing earlier modal stability analysis. Based on the parallel flow assumption, singular value decomposition is applied to obtain the optimal linear combination of global crossflow modes. The optimal disturbance exhibits significant transient growth in the initial short distance and progressively follows the path of the most unstable mode downstream. The largest transient energy gain is observed for disturbances at around 40 kHz close to the most amplified modal frequency and tends to increase with the Reynolds number. The optimal disturbance initially exhibits two amplitude peaks in the azimuthal direction, one lying in the leeward region where the unstable crossflow modes reside and the other in the windward region where the adjoint modes exist. As the optimal disturbance travels downstream, the second amplitude peak rapidly shifts toward the leeward side and reaches the optimal energy gain when it eventually merges with the first amplitude peak. The evolution process of the optimal disturbance indicates that the optimal disturbance might have exploited the locally crossflow instability through traveling from the windward side to the leeward side.

A Trimode Self-Cleaning Composite Membrane with an Eco-friendly Substrate for Energy-Saving Wastewater Recycling

A separation membrane with low or clean energy costs is urgently required for energy-saving and long-term service since electric energy generated from burning non-renewable resources will gradually cause a burden to the environment. At present, the conventional membrane being used in one mode is critical for a variety of scenarios in real life, which suffers from a trade-off effect, short service life, being difficult to recycle after damage. Herein, we report a trimode purification membrane composed of an eco-friendly polycaprolactone (PCL) substrate and functional graphene dioxide/polyaniline (GO/PANI) particles. Due to the photothermal transfer and photocatalytic properties of GO/PANI blend, the composite membrane can absorb 97.44% solar energy to handle natural seawater or mixed wastewater, which achieves a high evaporation rate of 1.47 kg m−2 h−1 in solar-driven evaporation mode. For the photocatalytic adsorption–degradation mode, 93.22% of organic dyes can be adsorbed and degraded after 12 h irradiation under 1 kW m−2. Moreover, electric-driven cross-flow filtration mode as a supplement also shows effective rejection over 99% for organic dyes with a high flux over 40 L m−2 h−1 bar−1. The combination of solar-driven evaporation, photocatalytic adsorption–degradation, and electric-driven cross-flow filtration demonstrates a prospective and sustainable strategy to generating clean water from sewages.Graphical A trimode self-cleaning composite membrane of bio-degradable substrate PCL and functional particles GO/PANI were successfully fabricated, which can purify natural seawater or mixed wastewater stably in solar-driven evaporation mode, handle organic dyes by reduction–oxidation chemical transformation in photothermal adsorption–degradation mode, and be applied in cross-flow filtration mode driven by electric as a supplement for rainy, cloudy days, or at night.

La0·8Mn0·2FeO3 impregnated ceramic membrane for membrane fouling elimination via peroxymonosulfate activation

To endow SiC ceramic membranes a catalytic self-cleaning capability, a pore-functionalized SiC ceramic membrane with impregnated a perovskite-type catalyst La0·8Mn0·2FeO3 was fabricated by a urea-assisted one-step combustion method. Diffraction of X-ray (XRD), canning electronic microscopy (SEM) with an energy dispersion X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the effects of the impregnating of La0·8Mn0·2FeO3 on SiC membrane pore-structure (La0·8Mn0·2FeO3-CM). The catalytic self-cleaning performance of the as-prepared membranes was assessed through peroxymonosulfate (PMS) activation under a cross-flow filtration mode. Results indicate that La0·8Mn0·2FeO3 has been successfully impregnated into the macropores of SiC membranes without pore blocking, and 92.4 % of the flux recovery rate (FRR) was achieved when the PMS concentration was 70 mM and catalytic flushing time was 45 min. Therefore, the La0·8Mn0·2FeO3 impregnated SiC membrane exhibited excellent catalytic self-cleaning property, which can effectively avoid the environmental pollution and the deterioration of membrane materials caused by chemical cleaning for membrane fouling. In addition, the radical quenching experiment and electron spin resonance (EPR) tests were conducted in the catalytic self-cleaning process, and the results suggested that the hydroxyl radical (⋅OH) and sulfate radical (SO4•‾) are simultaneously captured and ⋅OH is the dominant active species. This study embarks on a novel and environmental friendly membrane cleaning approach for irreversible fouling eliminates in diverse membrane separation applications.

Crossflow Instability on a Swept Fin–Cone with Variable Nose Bluntness in Mach 6 Flow

Experiments and computational analysis have been conducted to study instabilities in the boundary layer over a swept fin–cone geometry in hypersonic flow. Experiments were carried out at the United States Air Force Academy’s Mach 6 Ludwieg Tube. Infrared thermography was employed to assess the surface temperature distribution, particularly the thermal striations on the fin that indicated a crossflow-dominated transition. Increasing the unit Reynolds number increased heating and moved the crossflow-transition front closer to the fin leading edge. Stability analysis based on the linear parabolized stability equations identified unstable stationary crossflow modes across the range of tested unit Reynolds numbers, and the most amplified disturbances were found to have wavelengths of 2–4 mm. The experimentally observed thermal striations were analyzed and found to have initial wavelengths of 2–5 mm but eventually formed higher-amplitude structures with a wavelength of approximately 10 mm. Discrete roughness elements of different diameters and spacings were implemented near the fin leading edge. Boundary-layer transition onset was found to be delayed with a subsequent lowering of the fin surface heating, with discrete roughness elements having a wavelength of 13.33 mm.

Cross-flow instability on a swept-fin cone at Mach 6: characteristics and control

Experiments were performed to document the complex flow field around and over a $70^{\circ }$ swept fin mounted on a $7^{\circ }$ half-angle right-circular cone in a Mach 6 free-stream. Of particular interest is the turbulent transition of the boundary layer over the swept fin, which is expected to be dominated by a cross-flow instability. Stationary features in the surface temperature distribution over the fin are documented using infrared thermal imaging. These were processed further to determine average spatial Stanton number distributions over the fin. Wavelet analysis of the Stanton number distributions revealed stationary patterns with wavelengths near the fin leading edge that were consistent with linear theory predictions of stationary cross-flow modes. Further from the leading edge, the wavelength of the stationary patterns was observed to increase prior to turbulence onset. Based on these observations, specially designed arrays of discrete roughness elements (DREs) were investigated as a means of delaying turbulence transition with the objective of reducing surface heat flux on the swept fin. The DRE designs followed our previous approach used for cross-flow transition control (Corke et al., J. Fluid Mech., vol. 856, issue 10, 2018, pp. 822–849; Arndt et al., J. Fluid Mech., vol. 887, 2020, A30). These focused on either the shorter wavelengths near the leading edge, or the longer wavelengths that developed near turbulence onset. With regard to delaying transition and reducing the surface heat flux, the DREs that focused on the larger wavelengths of stationary modes were most effective. The fin included an array of pressure sensors that were used to document travelling disturbances that could include those associated with travelling cross-flow modes. Phase analysis of the pressure fluctuation time series was used to determine the wavelength, wave angle and phase speed that were consistent with the travelling cross-flow modes. Cross-bicoherence analysis between the stationary and travelling disturbances indicates a nonlinear phase locking that can account for the development of the longer-wavelength stationary features in the surface heat flux, presumed to be due to stationary cross-flow modes, prior to turbulence onset.

Sustainable and Rapid Water Purification at the Confined Hydrogel Interface.

Emerging organic contaminants in water matrices have challenged ecosystems and human health safety. Persulfate-based advanced oxidation processes (PS-AOPs) have attracted much attention as they address potential water purification challenges. However, overcoming the mass transfer constraint and the catalyst's inherent site agglomeration in the heterogeneous system remains urgent. Herein, the abundant metal-anchored loading (≈6-8g m-2) of alginate hydrogel membranes coupled with cross-flow mode as an efficient strategy for water purification applications is proposed. The organic flux of the confined hydrogel interfaces sharply enlarges with the reduction of the thickness of the boundary layer via the pressure field. The normalized property of the system displays a remarkable organic (sulfonamides) elimination rate of 4.87 × 104mg min-1 mol-1. Furthermore, due to the fast reaction time (<1min), cross-flow mode only reaches a meager energy cost (≈2.21Wh m-3) under the pressure drive field. It is anticipated that this finding provides insight into the novel design with ultrafast organic removal performance and low techno-economic cost (i.e., energy operation cost, material, and reagent cost) for the field of water purification under various PS-AOPs challenging scenarios.

Real Gas Effects on Receptivity to Roughness in Hypersonic Swept Blunt Flat-Plate Boundary Layers

Temperatures within the boundary layers of high-enthalpy hypersonic flows can soar to thousands or even tens of thousands of degrees, leading to significant real gas phenomena. Although there has been significant research on real gas effects on hypersonic boundary layer stability, their impact on the boundary layer’s receptive stage is still poorly understood. Most aerodynamic boundary layers in flight vehicles are three-dimensional. Because of complex geometry and significant crossflow effects, the crossflow mode in three-dimensional boundary layers is crucial in hypersonic vehicle design. In this study, a linear stability analysis (LST) accounting for chemical nonequilibrium effects (CNE) and its adjoint form (ALST) is developed to investigate the real gas effects on the stability and receptivity of stationary crossflow modes. The results indicate that real gas effects significantly influence the receptivity of stationary crossflow modes. Specifically, chemical nonequilibrium effects destabilize the crossflow modes but reduce the receptivity coefficients of the stationary crossflow modes. The Mach number effect was also investigated. It was found that increasing the Mach number stabilizes the stationary crossflow modes, but the receptivity coefficients increase. As the Mach number progressively rises, these effects alternately dominate, leading to a non-monotonic shift in the transition position.

Measurement and analysis of crossflow instability modes on a 7-degree yawed cone at Mach 6

In this work, the crossflow instability modes on a 7° half-angle cone with 6° angle of attack at Mach 6 have been experimentally studied. To begin with, the complete laminar-to-turbulence transition process is acquired by infrared thermography, and the heat flux streaks caused by the stationary crossflow vortices are distinct over the areas of leeward side. Further wavelet analysis reveals a dominant wavenumber of the stationary crossflow vortices, which is centered at about k = 50. Subsequently, the spatial distribution characteristics of the traveling crossflow instability (f = 20–50 kHz) and high-frequency instabilities (f = 100–500 kHz) are acquired between the azimuthal angle Φ = 90°–150° (windside to leeside) through wall mounted pressure sensors. The results of spectral and wavelet analysis indicate that the two types of instability are the traveling crossflow instability and its secondary instability, respectively. Further bispectral analysis is used to show that these high-frequency waves undergo several quadratic phase-coupled interactions with themselves to produce harmonics, as well interact with low-frequency waves that results in spectral broadening.

Amino-functionalization of tungsten oxide nanoparticles for stable decoration in the active layer of alumina-supported inorganic-organic hybrid membrane with super-wettable and photocatalytic self-cleaning surfaces for crude oil-in-water emulsion separation

The ceramic membrane was hybridized with an amino-functionalized inorganic metal oxide and organic polymer to achieve the optimal oil and water surface wettability and photo-catalytic self-cleaning capability. The resulting membrane was used for the treatment of crude oil-contaminated wastewater under cross-flow filtration mode. The fundamental functional material, tungsten oxide nanoparticles (NH2-WO3 NPs) modified by aminopropyl triethoxysilane (APTES) was created and coated on the alumina ceramic support surface via interfacial polymerization, in which the material covalently cross-links on the membrane's active layer in the presence of terephthaloyl chloride (TPC) as a cross-linker and piperazine (PIP) as an external amine. Achieving a unique combination of oil and water surface wettability- superhydrophilicity (0° water-in-air contact angle) and underwater super-oleophobicity (160.25° under-water oil contact angle) was the key to creating the water-permeating NH2-WO3/PA@alumina ceramic membrane. The second advantageous feature of the membrane is its capacity for self-cleaning, which results from WO3 NP's innate photocatalytic activity that has been further enhanced by amino functionalization. A water permeate flux of up to 250 L m−2 h−1 and an oil/water separation efficiency of nearly 100 % were attained for an oil concentration of 50 ppm of crude oil-in-water emulsion when NH2-WO3/PA@alumina ceramic membrane was employed as a separation medium in a cross-flow filtration system for the separation of crude oil-in-water emulsion. Furthermore, the permeate flux decreased to ∼25 % of its initial flux after using NH2-WO3/PA@alumina ceramic for approximately 210 min. This was caused by organic pollutants in the oily water clogging the membrane pores. The permeate flux was recovered by exposing the membrane to UV light for photo-catalytic self-cleaning. Due to its water-passing nature, this membrane has high efficiency. Additionally, because the self-cleaning add-on removes the need for chemical cleaning, it is environmentally friendly.

Robust fabrication of sulfonated graphene oxide/poly (ether sulfone) catalytic membrane reactor for efficient cellulose hydrolysis and product separation

The efficient conversion of cellulose to high value-added products is important for the utilization of cellulose biomass. Achieving efficient cellulose hydrolysis and timely products separation is the essential target. Herein, a modified sulfonated graphene oxide/polydopamine deposited polyethersulfone (mGO(SO3H)-PDA/PES) membrane reactor, combining in the same unit a conversion effect and a separation effect, was prepared by suction filtration and subsequent polymerization and adhesion. The structure of PES membrane and deposition of PDA was regulated to sure that small molecules can pass through the membrane, while cellulose could not. As a result, the mGO(SO3H)-PDA/PES membrane realized the efficient cellulose hydrolysis and timely products separation under cross-flow circulation mode at 0.1 MPa, avoiding the further degradation of reducing sugar products. The yields of total reducing sugar (TRS) and glucose in separated hydrolysate reached 93.2 % and 85.5 %, respectively. This strategy provides potential guidance for efficient conversion of cellulose.

Performance and Thermal Stress Evaluation of Full-Scale SOEC Stack Using Multi-Physics Modeling Method

A three-dimensional computational fluid dynamics (CFD) method coupled with multi-physics phenomena is developed and applied for a 10-cell full-scale SOEC stack in this study. Effects of gas flow patterns, operating temperature, and manifold configurations are simulated and analyzed for stack performance and thermal stress. It is demonstrated the hydrogen production and thermal stress obtained in cross-flow mode stack are about 8% and 36 MPa higher compared to that in other flow cases. Furthermore, it is found the temperature gradient is the predominant factor affecting the thermal stress distribution and failure probability. Lastly, a stack arrangement with 2-inlet and 1-outlet is proposed and analyzed to enhance gas distribution uniformity within the cell channels. The findings of this study hold significance as a reference for investigating the impact on the SOEC stack performance and thermal stress distribution.

Zwitterionic material for construction of an antifouling polyamide thin film composite membrane

Zwitterionic materials containing equal proportions of positively and negatively charged groups have been used to provide membranes with antifouling capabilities. This study focuses on the modification of a commercially available polyamide thin-film composite membrane with a zwitterionic material and investigates its effectiveness in fouling mitigation. The zwitterionic material, sulfobetaine vinylimidazole (SBVI), was synthesized by reacting 1,3-propane sulfone with 1-vinyl imidazole. A NF90 polyamide membrane functionalized with propagyl bromide was modified by the polymerization of SBVI on its surface. Various techniques were used to verify the successful modification of membranes. The water flux and salt rejection of the pristine and modified membranes were measured under comparable stabilization conditions, and showed an increase in salt rejection and a decrease in permeability for the modified membrane because of additional membrane resistance. However, fouling tests conducted with a wide range of foulants in cross-flow filtration mode showed a lower fouling ratio and higher recovery ratio for the modified membrane than for the pristine membrane. The enhancement in the antifouling characteristics of the modified membrane was mainly attributed to the improvement in hydrophilicity resulting from the zwitterionic brushes. Our results demonstrated the fouling resistance is further reinforced in an ionic environment through the “salting-in” effect.

Tailored ethylenediamine-functionalized graphene oxide membrane on kaolin hollow fibers for pectin concentration

Pectin is a valuable product that can be extracted from waste fruit peels. Here we propose the use of graphene oxide (GO)-based membranes for pectin concentration. The synthesized GO was functionalized with ethylenediamine (EDA) to molecularly design the GO framework. Kaolin hollow fibers with asymmetric pore distribution were used as a porous substrate for GO/EDA deposition. A GO/EDA layer with a thickness of 2.86 ± 0.24 μm was assembled on the substrate by the simple vacuum-assisted deposition method. After GO/EDA depositions, the water permeance of the pristine kaolin hollow fibers reduced from 8.46 ± 0.17 to 0.52 ± 0.03 L h−1·m−2·kPa−1. A pectin aqueous extract from orange peels was filtered at cross-flow mode through the prepared membranes and the steady-state fluxes through pristine and GO/EDA-coated hollow fibers were 56 ± 2 and 20 ± 3 L h−1 m−2, respectively. The GO/EDA-coated membrane presented greater pectin selectivity than the pristine hollow fiber. The GO/EDA-coated hollow fiber concentrated the galacturonic acid, phenolic, and methoxyl contents in 19.5, 17.4, and 29.2 %, respectively. Thus, filtration through the GO/EDA-based membrane is a suitable alternative for pectin concentration.

Functionalized graphene-based ultrafiltration and thin-film composite nanofiltration membranes for arsenic, chromium, and fluoride removal from simulated groundwater: Mechanism and effect of pH

Groundwater contaminant removal using ultrafiltration (UF) and nanofiltration (NF) membranes is complex due to limitations such as low selectivity-permeability and membrane fouling tendency. In this study, we fabricated a thin film composite (TFC) membrane over a highly permeable mixed matrix support UF membrane using sulfonic acid functionalized graphene oxide (SGO) and polyethersulfone (PES) for groundwater remediation application. The pure water permeability of the PES-SGO-TFC membrane was threefold (3.09 LMH bar−1) compared to the pristine PES-TFC membrane. The membrane showed excellent organic fouling resistance with more than 95% flux recovery. The salts and contaminant removal were checked in a cross-flow mode to understand a more practical approach to the applicability of the developed PES-SGO-TFC membrane. The membrane rejected Cr(VI), As(V), and fluoride to the extent of ∼89%, ⁓99%, and ∼77%, respectively, at pH ⁓7. The membrane separation performance varied as a function of pH, with more than 90% removal for monovalent fluoride at higher pH values. In a simulated groundwater matrix, the membrane demonstrated promising results for rejecting these ions. However, the simultaneous rejection of As(V) and fluoride may be impacted by interfering co-ions. This study offers a novel approach for developing highly permeable support UF-modified TFC membranes for better separation for groundwater remediation.

Coexistence of stationary Görtler and crossflow instabilities in boundary layers

The coexistence of stationary Görtler and crossflow instabilities in boundary layers covering incompressible to hypersonic regimes is investigated by varying the local sweep angle, pressure gradient, wall curvature, and wall temperature using linear stability analysis. The results show that increasing the local sweep angle under a fixed concave curvature in incompressible boundary layers leads to the appearance of two unstable modes at certain sweep angles, which is conventionally known as the “changeover” regime between the crossflow and Görtler modes. This study identifies a synchronization between the two modes under this condition, which is similar to multiple Görtler modes and thus referred to as Görtler–crossflow modes. Three scenarios are presented to describe the possible development of these modal instabilities. In addition, increasing the concave curvature destabilizes the instability, while introducing a pressure gradient stabilizes the instability and results in a shrinkage of the unstable band of the spanwise wavenumber, as reported in the literature. In supersonic and hypersonic boundary layers, synchronization can occur near specific sweep angles and under cold wall conditions in supersonic boundary layers. As Mach number increases, the synchronization regime shifts toward lower sweep angles and wall temperature, in which the former reflects a decline in crossflow strength relative to Görtler instability, while the latter indicates the influence of thermal effects on synchronization. In hypersonic boundary layers, the crossflow instability is insignificant compared with the Görtler instability. No synchronization is identified under various parameter changes, and the first Görtler–crossflow mode dominates across the entire spanwise wavenumber ranges.

Janus membranes with opposite wettability prompting the synchronous synthesis and separation of hydrophobic ionic liquids

Traditional production of ionic liquids (ILs) includes isolated processes of synthesis followed by extraction purification with organic solvents. A remained challenge is to produce these green solvents by a simultaneous synthesis and separation procedure disusing volatile organic solvents. Herein, we describe a framework for the synchronous synthesis and separation of hydrophobic ILs based on an environmentally benign membrane reactor system. A Janus hollow fiber membrane reactor (JHFMR) with a thin and charged inner surface (IL-phobic) and an IL-philic outer surface is prepared by mussel-inspired co-deposition technique. The hydrophilic lumen surface supplies a reaction zone for anion metathesis. The inner surface charge destabilizes the emulsified target ILs dispersed in water. The deemulsified ILs actively pass through the JHFMR from IL-phobic side to IL-philic side driven by the gradient of surface energy. Multiple JHFMRs are ultimately assembled to prepare a JHFMR module for achieving a continuous and large-scale production of hydrophobic ILs in a cross-flow mode. The final ILs yield under a low reactant concentration (l.0 mol/L) is enhanced to reach 96% after 30 h by doubling the packing density of module. The residual water content in IL products is below 1.0 wt%. Other ion impurity is negligible (Li+ < 10 ppm, and Br- is below the detectable limit). Such enormously low impurity level is attributable to the synchronous separation of ILs once they are synthesized within the JHFMR module. Moreover, the module maintains a stable performance after repeated cycles. The proposed all-in-one strategy has a potential for continuous preparation of hydrophobic ILs at a large scale, with high yield and low impurity under “greener” operating conditions, e.g., at room temperature and avoidance of using volatile organic solvents.