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Acetic acid is an essential intermediate chemical in industry. Traditional inorganic membrane cannot meet the demand of high‐efficient dehydration and polymeric membrane is restricted by its low organic solution resistance. In this work, a novel aciduric pervaporation composite membrane was successfully generated by fabricating an ultrathin polysulfonamide (PSA) layer on the polyacrylonitrile (PAN) nanofibrous substrate via interfacial polymerization (IP) method. Through the optimization of fabrication process including selecting the suitable structure of diamine (taking three types aliphatic amines as candidates), optimizing the concentration of two phase solutions, the resultant thin‐film nanofibrous composite (TFNC) membrane was fabricated by using aliphatic amine triethylenetetramine (TETA: 3.0 wt%) and 1, 3‐benzenedisulfonyl chloride (BDSC: 1.0 wt%) as IP monomers and the network structure with suitable sieving size was constructed. The ultrathin aciduric PSA selective layer (thickness: 104 ± 15 nm) endowed the TFNC membrane with excellent separation efficiency. For dehydrating 70 wt% acetic acid aqueous solution at 60°C, PSA‐3.0‐1.0/PAN TFNC membrane exhibited competitive separation efficiency and great acid stability. It possessed extremely high permeate flux (15,321 g/m2 h) with stable separation factor (109). For long‐term acid dehydration evaluation, PSA/PAN membrane showed great stability during 7 days pervaporation. This work took advantage of traditional IP method for designing a novel pervaporation membrane with aciduric chemical structure, suggested an effective and facile approach to develop novel pervaporation membranes for harsh environment separation. [ABSTRACT FROM AUTHOR]

Solar-driven membrane distillation (SDMD) had shown greater potential for desalination due to low energy consumption and convenient energy source compared to traditional membrane distillation. In this study, an innovative photothermal dual-layer hydrophilic/hydrophobic composite nanofibrous membrane consisting of polyacrylonitrile (PAN) nanofibrous membrane embedded with silver nanoparticles (Ag NPs) as hydrophilic layer and polyvinylidene fluoride (PVDF) nanofibrous membrane modified by polydimethylsiloxane (PDMS) as hydrophobic layer was constructed to be applied for efficient SDMD in desalination field. The photothermal particles loaded in the hydrophilic layer not only avoided clogging of the pores of the hydrophobic layer but also could be wetted completely to fully heat the feed fluid for achieving great photothermal conversion efficiency while the porous hydrophobic layer could prevent leakage of salt solute to attain high retention and vapor flux. Hence, the optimized composite nanofibrous membrane exhibited a high flux of 1.2 kg/m2/h with energy conversion efficiency of 75.2% and stable permeate conductivity (2.5 μs/cm) during 10 h SDMD test period (3.5 wt% NaCl salt feed) under 1 kw/m2 solar irradiation. Therefore, the photothermal dual-layer hydrophilic/hydrophobic composite nanofibrous membrane had promising application for desalination and provide a valuable inspiration in the development of membranes for membrane distillation. [Display omitted] • The composite nanofibrous membrane possessed unique dual-layer hydrophilic/hydrophobic structure. • The hydrophilic layer could be wetted completely to fully heat the feed solution with excellent photothermal effect. • The optimized composite nanofibrous membrane exhibited high flux and energy conversion efficiency for SDMD. [ABSTRACT FROM AUTHOR]

• Highly permeable LNF membrane was fabricated by filtration-assisted interfacial polymerization. • The GNs barrier layer endowed the LNF membrane with long-term stability and sustainability. • The GNs barrier layer enables the LNF membrane superior dye degradation ability. To effectively separate salt/dye mixtures from textile wastewater, the development of nanofiltration (NF) membranes with stable and loose structure for high permeability is getting an urgent task. In this study, a novel loose thin film nanofibrous composite NF membrane was fabricated by filtration-assisted interfacial polymerization for dye/salt separation, in which two-dimensional g-C 3 N 4 nanosheets (GNs) modified with polyethylenimine (PEI) were sturdily integrated together via reaction with organic phase trimesoyl chloride (TMC) to form a polyamide (PA) soldered GNs barrier layer onto polyacrylonitrile (PAN) nanofibrous substrate. Benefiting from the inimitable photocatalytic activity of GNs, the organic dyes adhered and accumulated on the membrane surface could be easily cleared up under visible light irradiation for the great recyclability of the composite membrane. The optimized robust GNs composite membrane possessed high water permeability (40.9 L m−2 h−1 bar−1), superior dyes rejections (>94%) for Congo Red, Methyl Blue and Reactive Black 5 and low salt rejections (<7%) for NaCl and Na 2 SO 4 for excellent salt/dye separation performance (the dye/NaCl separation factor was up to 236). The resultant GNs barrier layer endowed the composite membrane with long-term stability and sustainability, the dye permeability could still recover to 93% of the initial membrane during three cycles of visible light irradiation. Therefore, this work provided a new solution for the design and development of loose NF membrane for the sustainable separation of salt/dye wastewater. [ABSTRACT FROM AUTHOR]

Rapid and thorough removal of heavy metal ions in wastewater is critical for the urgent need of clean water. Herein, we prepared a high-performance thin film nanofibrous composite (TFNC) membrane consisting of a polyacrylonitrile (PAN)-UiO-66-(COOH) 2 composite nanofibrous substrate (CPAN) and a calcium alginate (CaAlg) skin layer. Owing to abundant adsorption sites of UiO-66-(COOH) 2 MOF, the optimal CPAN-2 nanofibrous substrate showed excellent adsorption capacity for lead ions. The maximum Pb2+ adsorption capacity of CPAN-2 substrate calculated by Langmuir isotherm model was 254.5 mg/g. Meanwhile, due to the relatively loose structure of CaAlg skin layer, this TFNC membrane showed high water permeate flux about 50 L m−2h−1 at 0.1 MPa, and the rejection for dyes was higher than 95%. Therefore, CaAlg/CPAN TFNC membranes were appropriate for dynamic adsorption/filtration to remove Pb2+. Compared with original CaAlg/PAN membrane, the optimal CaAlg/CPAN TFNC membrane showed much better ability to treat Pb(II)-containing wastewater and had good recyclability. Most importantly, the CaAlg/CPAN TFNC membrane could treat 7659 L m−2 wastewater containing single lead ions under WHO drinking water standard, and effectively deal with more simulated lead-containing wastewater. This work could provide a substitutable solution for effective removal of heavy metal ions and other various contaminants in wastewater. [Display omitted] • A new TFNC membrane strategy was proposed to treat heavy metal ions wastewater. • The PAN-UiO-66-(COOH) 2 nanofibrous substrate showed excellent adsorption capacity for Pb(II). • The CaAlg skin layer of TFNC membrane possessed high organic rejection with high permeation flux. • The TFNC membrane could quickly and efficiently handle abundant Pb(II)-containing wastewater. [ABSTRACT FROM AUTHOR]

• A TpPa layer with nanorods was prepared as an auxiliary interlayer. • TpPa interlayer played a decisive role for the formation of PA skin layer. • The PA/TpPa-12/PAN membrane showed excellent nanofiltration performance and NaCl/dyes selectivity. Nanofiltration (NF) membrane with high permeability and selectivity is extremely crucial for water purification. Herein, we prepared a high permeability thin-film nanofibrous composite (TFNC) membrane via interfacial polymerization (IP) technique assisted by introducing TpPa covalent organic frameworks (COFs) interlayer with nanorods on the polyacrylonitrile (PAN) nanofibrous substrate for NF. TpPa COFs interlayer with nanorods played a decisive role in adjusting the structure and performance of polyamide (PA) skin layer. On the one hand, TpPa COFs interlayer could regulate the diffusion and transfer rate of piperazine in the aqueous phase solution during IP process, which would modulate the mophology and reduce the thickness of the PA skin layer. Meanwhile, the TpPa COFs nanorods could create massive voids under PA layer to enhance the flux of TFNC membrane. Additionally, the TpPa COFs with nanoporous structure themselves also provided additional nanochannels for water transport. The structure of COFs interlayer could be tuned by altering the Pa contents of aqueous phase solution, which further optimized the overall performance. The permeation water flux of optimal TFNC membrane could reach to 104.8 L m−2 h−1 with a relatively high rejection of 98.4% for Na 2 SO 4 under 0.5 MPa, which was about 2.3 times than that of the unmodified PA membrane prepared without TpPa COFs interlayer. Besides, the optimal membrane exhibited good selectivity to NaCl/dye solution (NaCl/Acid Fuchsin was 402.5 and NaCl/Congo Red was 398.0) and long-term test stability. This work showed a new avenue to prepare high-performance NF membrane for the potential applications in water desalination and dye wastewater recovery. [ABSTRACT FROM AUTHOR]

In this work, a novel Co 3 O 4 @CeO 2 nanofibrous membrane was prepared by the combination of interfacial defect engineering strategy and coaxial electrospinning for unusual levofloxacin degradation. Implanting active Co 3 O 4 into CeO 2 derived from Ce-UiO-66 created more oxygen vacancies and improved the interfacial interaction (electron transfer and specific surface area). In addition, accelerated redox recycling occurred on the catalyst surface because of the cooperation of Co sites and Ce sites. As a result, the optimal Co 3 O 4 @CeO 2 nanocomposite showed an unexpectedly improved degradation efficiency of levofloxacin with a rate constant higher than 6.9 times (CeO 2) and 2.6 times (Co 3 O 4), superior elimination (>98%) of antibiotic (norfloxacin, tetracycline and doxycycline hydrochloride) and dyes (methylene blue, rhodamine b, methyl orange and crystal violet). Moreover, C-type hollow structure nanofibers with increased reaction area were prepared by coaxial electrospinning to support nanoparticles for consecutive wastewater treatment. The prepared nanofibrous membrane with loading 50 wt% Co 3 O 4 @CeO 2 (PC50 NFMs) exhibited loose structure, resulting in 168.2 ± 12 L m−2 h−1 of permeability driven by gravity, while 164.2 L m−2 of levofloxacin was efficiently treated. Besides, the PC50 NFMs had satisfactory reusability and stability in real water bodies. This work paved a new avenue to control water pollution through the design of membranous catalysts. [Display omitted] • Active Co 3 O 4 was implanted into CeO 2 derived from Ce-UiO-66 via interfacial defect engineering strategy. • CC2 with improved electron transfer rate and specific surface area showed an enhanced degradation efficiency of levofloxacin. • PC50 NFMs with loose structure and hydrophilicity were prepared for the consecutive wastewater treatment. • PC50 NFMs showed considerable dynamic degradation efficiency, reusability and stability. [ABSTRACT FROM AUTHOR]

High performance thin-film nanofibrous composite (TFNC) membranes with Turing structures were constructed by interfacial polymerization (IP) of trimesoyl chloride (TMC) and piperazine (PIP) tuned with high content salt (NaCl) in aqueous phase onto a polyacrylonitrile (PAN) nanofibrous mat for nanofiltration (NF). The concentration of salt in aqueous phase played a key role in the structural transition of polyamide (PA) membrane surfaces with two type Turing structures from the crossed ridge networks to crowed nodular arrays. The introduction of NaCl induced the uneven distribution of the IP reaction and could fine-tune the hydrophilicity and compactness of the formed ultrathin PA layer. The skillful manipulation of IP by regulating the NaCl content in aqueous phase enabled a great improvement in NF performance. Under 0.5 MPa, the flux of the optimized TFNC membrane (20.0 wt% NaCl in aqueous phase) reached 129.0 L m-2 h-1 (Na 2 SO 4 rejection was 99.1%) which was approximately 2.5 times greater than that of the original membrane fabricated without salt addition. Moreover, the resultant membrane exhibited excellent stability and anti-fouling properties for long-term use. This approach is easy to be connected with commercialized IP technology to prepare high-performance NF membranes. • NaCl was used as an additive in aqueous phase during interfacial polymerization. • Two type Turing structures of PA separating skin layer were formed. • The membrane exhibited high and stable nanofiltration performance. [ABSTRACT FROM AUTHOR]

Hemodialysis membranes are critical components for hemodialysis process. Herein, we demonstrate a new kind of hemodialysis membrane based on polyacrylonitrile (PAN) electrospun scaffold and heparin-poly(vinyl alcohol) (heparin-PVA) hydrogel coating. Manipulation of coating solution rheology by control of heparin content enabled the creation of membranes with sub-micron ridged surface topography. The results of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra confirmed that heparin was covalently incorporated in the hydrogel layer; meanwhile, the scanning electron microscopy (SEM) and atomic force microscopy (AFM) images gave clear evidence that the fabricated membranes had typical sub-micron ridge structure. The results revealed that the sub-micron ridged surface topography and heparin chemical modification synergistically endowed the membranes with excellent permeability, protein antifouling properties, anticoagulant activity, cytocompatibility, and dialysis performances. Especially, when the heparin/PVA weight ratio was 20%, the water flux of the membrane was 371.8 L/m2h. Its urea clearance was 86 mL/min, lysozyme clearance was 60 mL/min, and bovine serum albumin clearance was as less as 5.5 mL/min. Image 1 • Novel heparin-PVA/PAN TFNC hemodialysis membranes were obtained. • Sub-micron ridge structure was constructed on the TFNC membranes. • The TFNC membranes were modified by the combined physical and chemical modification. • Both biocompatibility and dialysis performance of the modified membrane was improved. [ABSTRACT FROM AUTHOR]

Polymeric hemodialysis (HD) membranes with limited porosities, tortuous pores, and broad pore size distributions suffer from a trade-off between permeability-i.e., how fast toxins pass through the membranes-and selectivity-i.e., to what extent necessary proteins are retained. Here, a novel thin-film nanofibrous composite (TFNC) membrane, composed of an electrospun polyacrylonitrile (PAN) nanofibrous support layer and a chemically cross-linked polyvinyl alcohol (PVA) separation layer filled with heparin functionalized multi-walled carbon nanotubes (Hep-g-pMWCNTs), was demonstrated for efficient and safe HD application. Combining dialysis simulation experiments and pore-flow model, we demonstrated that the formation of free nanogaps at the interface between Hep-g-pMWCNTs and PVA matrix provided additional directional nanochannels for toxins to transport. The membranes showed efficient toxins removal without sacrificing selectivity (with the urea clearance of 88.2%, lysozyme clearance of 58.6%, and bovine serum albumin retention of 98.4% in a 4 h simulating dialysis). Especially, the efficiency in removing middle molecule toxins increased obviously compared with the values reported to date. Besides, the membranes exhibited excellent hemocompatibility: high resistance to protein adsorption, suppressed platelet adhesion, favorable anticoagulant activity, limited hemolysis ratio, and low complement activation. These facts suggested that the Hep-g-pMWCNTs/PVA/PAN TFNC membranes with superior comprehensive performances presented great potential for HD application. Image 1 • Novel TFNC membranes containing toxin transport nanochannels were obtained. • Heparin functionalized MWCNTs were synthesized via a biomimetic approach. • The membranes exhibited efficient toxins removal without sacrificing selectivity. • The membranes showed low protein adsorption and good blood compatibility. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The wide application of composite nanofiltration membrane is greatly restricted by the "trade-off effect" between selectivity and permeability. In this work the trade-off effect was broken by an eco-friendly construction of loose chitosan (CS) coating layer on highly porous polyacrylonitrile (PAN) electrospun nanofibrous scaffold. The loose CS layer was accomplished by stabilizing CS with anionic dyes fouling to enhance the membrane permeability, because their electrostatic interaction was much weaker than CS membrane crosslinked by traditional chemical crosslinkers. To the best of our knowledge, few researches were reported on the dye-fouled CS nanofiltration membrane. The optimized membranes demonstrated excellent filtration performance for anionic dyes separation with superior permeate flux (˜139.1 L m−2 h−1 at 0.1 MPa) and high rejection (˜99.8%) to direct red 80 (DR80) solution of 100 mg/L, as well as cationic dyes separation (like alcian blue 8GX (AB8GX) with rejection of 99.7%). Besides, the CS-DR80/PAN membranes exhibited excellent long-term durability and antifouling nature due to low surface roughness and high surface hydrophilicity. The superior nanofiltration performance was chiefly attributed to the coordinated effect of two-tier structure: the hydrophilic loose negatively-charged barrier layer and the highly porous PAN nanofibrous scaffold. The loose barrier layer and electrospun PAN nanofibrous substrate can guarantee the high permeability, and the negatively charged membrane surface can assure the high rejection due to Donnan repulsion. This strategy not only abridges the complicated process, but also eliminates use of poisonous and expensive ingredients, which provides an eco-friendly and practical feasibility for textile wastewater treatment. [ABSTRACT FROM AUTHOR]