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In this work, polyacrylonitrile/aminated polymeric nanosphere (PAN/APN) nanofibers were prepared by electrospinning of monodispersed aminated polymeric nanospheres (APNs) for removal of Cr(VI) from aqueous solution. Characterization results showed that obtained PAN/APNs possessed nitrogen functionalization. Furthermore, the adsorption application results indicated that PAN/APN nanofibers exhibited a high adsorption capacity of 556 mg/g at 298 K for Cr(VI) removal. The kinetic data showed that the adsorption process fits the pseudo-second order. A thermodynamic study revealed that the adsorption of Cr(VI) was spontaneous and endothermic. The coexisting ions Na + , Ca 2+ , K + , Cl - , NO 3 - and PO 4 in solution dramatically decreased the removal performance. In the investigation of the removal mechanism, relative results indicated that the adsorption behavior possibly involved electrostatic adsorption, redox reaction and chelation. PAN/APN nanofibers can detoxify Cr(VI) to Cr(III) and subsequently chelate Cr(III) on its surface. The unique structure and nitrogen functionalization of PAN/APN nanofibers make them novel and prospective candidates in heavy metal removal.3- had little influence on Cr(VI) adsorption, while SO 4 2- in solution dramatically decreased the removal performance. In the investigation of the removal mechanism, relative results indicated that the adsorption behavior possibly involved electrostatic adsorption, redox reaction and chelation. PAN/APN nanofibers can detoxify Cr(VI) to Cr(III) and subsequently chelate Cr(III) on its surface. The unique structure and nitrogen functionalization of PAN/APN nanofibers make them novel and prospective candidates in heavy metal removal.

Membrane distillation (MD) is a promising technology for treating the concentrated seawater discharged from the desalination process. Interconnected porous membranes, fabricated by additive manufacturing, have received significant attention for MD technology because of their excellent permeability. However, their poor hydrophobic durability induced by the deformation of pores constrains their water desalination performance. Herein, an in situ three-dimensional (3D) welding approach involving emulsion electrospinning is reported for fabricating robust nanofibrous membranes. The reported method is simple and effective for welding nanofibers at their intersections, and the reinforced membrane pores are uniform in the 3D space. The results show that the in situ 3D welded nanofibrous membrane, with a stability of 170 h and water recovery of 76.9%, exhibits better desalination performance than the nonwelded (superhydrophobic) nanofibrous membrane and the postwelded (superhydrophobic) nanofibrous membrane. Furthermore, the stability mechanism of the in situ 3D welded nanofibrous membrane and the two different wetting mechanisms of the nonwelded and postwelded nanofibrous membranes were investigated in the current work. More significantly, the in situ 3D welded nanofibrous membrane can further concentrate the actual concentrated seawater (121°E, 37°N) to crystallization, demonstrating its potential applications for the desalination of challenging concentrated seawater.

The worldwide demands are rising for an energy-efficient and cost-effective approach that can provide advanced nanofibrous membranes with high filtration performance and superior antifouling properties. Here we report a novel synthesized fluorinated polyurethane (FPU) modified nanofibrous membrane optimized to achieve oil and non-oil aerosol particle filtration. By employing the FPU incorporation, the polyacrylonitrile/polyurethane (PAN/PU) composite membranes were endowed with superhydrophobicity with a water contact angle of 154° and superoleophobicity with an oil contact angle of 151°. Morphology, surface wettability, porous structure, and filtration performance could be manipulated by tuning the solution composition as well as the hierarchical structure. Furthermore, the as-prepared membranes can capture, for the first time, a range of different oil aerosol particles in a single-unit operation, with >99.9% filtration efficiency, by using the combined contribution of fiber diameter and surface roughness acting on the objective particles. Exemplified here by the construction of superamphiphobic nanofibrous membrane, numerous applications of this medium includes high efficiency particulate air filters, ultra-low penetration air filters, and respiratory protection equipment., (Copyright © 2014 Elsevier Inc. All rights reserved.)

In the adsorption treatment of colored water, it’s equally important to recover clean water and well separated dyes as well as reuse sorbent. Therefore, it is desired to develop adsorbents with prominent adsorption capacity, excellent selective adsorption for different dyes and robust chemical/mechanical stability. Herein, core-shell structured PDA/PEI@PVA/PEI nanofibrous membranes (NFMs), comprising uniform nanofibrous substrates and ultrathin PDA/PEI functional coating layer, were developed by a combination of PVA/PEI co-electrospinning and ultrathin PDA/PEI coating. The prepared NFMs exhibited excellent adsorption capacity for the anionic dyes and totally non-inductive to the cationic dyes on account of the strong electrostatic attraction/repulsion, which derived separation factor of anionic to cationic dyes as high as 970. The maximum adsorption capacity of PDA/PEI@PVA/PEI NFMs toward ponceau s and methyl blue were 1180 and 1290 mg/g, respectively, which is superior to the most results of current sorbents. Moreover, the hybrid NFMs demonstrated excellent chemical stability in the harsh environments and the frequent ad-/de-sorption cycling. [ABSTRACT FROM AUTHOR]

Electrospun nanofibrous membrane with ultrafine nanofibers, high porosity, and interconnected pores has attracted significant attention in high-flux membrane distillation (MD). However, the comparatively large pore size and low liquid entry pressure (LEP) of nanofibrous membranes often result in severe membrane scaling and wetting. In this work, superhydrophobic nanofibrous membranes with tailored membrane pore size and interface were successfully fabricated via sequential electrospinning and electrospraying approaches. Results revealed that the decreased membrane pore size and increased interface evaporation area could synchronously mitigate membrane scaling and improve water flux. Besides, the water recovery of the membrane could be further increased with the aid of antiscalant, e.g., polymer polyacrylic acid, toward treating a nearly saturated gypsum solution. The excellent concentration performance was attributed to the cooperation of the antiscalant that inhibits the nuclei formation and the engineered surface that reduced the adhesion between the membrane interface and gypsum crystals. Notably, the resultant membrane also showed a high initial flux of ∼40 L m−2 h−1 and high salts rejection efficiency of ∼100% in a continuous concentration process for over 100 h. Our study provides a promising methodology for preparing novel membrane surfaces to treat hypersaline wastewaters meeting the minimal/zero liquid charge target. [Display omitted] • Electrospraying was used to create roughened nanofibers for flux enhancement and stability. • Carbon black was added to the spraying solution to decrease nanofibrous membrane pore size. • The resultant membrane that cooperated with the antiscalant showed robust scaling resistance. • The scale resistance mechanism influenced by membrane pore size and antiscalant was also unveiled. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A superwetting nanofibrous membrane with strong corrosive resistance was prepared via co-electrospinning. • A highly charged polyethyleneimine was successfully grafted onto the hydrolyzed PAN/SPES nanofibrous membrane surface. • An electrostatic assembly method was used to construct the hierarchically structured nanofibrous membrane. • The composite nanofibrous membrane shows robust superwetting performance with a WCA of 0° and an UOCA of 161°. Abstract Creating a lotus-leaf-structured membrane surface with nano/microstructures plays a key role in the development of functional membranes for oil/water separation; however, fabrication of such membranes with uniform and compact nano/microstructures via an efficient and facile method have demonstrated to be challenging. Herein, a superwetting nanofibrous membrane with strong corrosive resistance was prepared via co-electrospinning of polyacrylonitrile/sulfonated polyethersulfone nanofibrous membrane (PAN/SPES NFM), amination of PAN and subsequent electrostatic assembly of lotus-leaf-structure by binding the negatively charged silica nanoparticles (SiO 2 NPs). Benefiting from the changes in pore size distribution and surface structure of nanofibrous membrane, the optimal membrane is endowed with an intriguing superhydrophilicity of 0°, an underwater superoleophobicity of 161°, and an outstanding oil proof pressure of 95.5 kPa. These fantastic features inspired the membrane to effectively separate the surfactant-stabilized oil-in-water microemulsion with a high water flux of 1852 ± 158 L m−2 h−1 and a high separation efficiency of 99.6% when a vacuum driven pressure of 10 kPa was applied. The layer-by-layer assembly method utilized in the construction of membrane roughness is expected to be applicable to a wide range of other selective wetting separation fields. [ABSTRACT FROM AUTHOR]