•Highly dispersed Pd-Cu/TiO2 was in situ fabricated by electrospinning to reduce NO3−.•In situ Pd-Cu/TiO2 showed high NO3− removal, superior selectivity and fast kinetics.•Well-dispersed and intimate connected Pd-Cu can improve catalytic performance.•Remarkable recyclability was obtained by preventing bimetals aggregation and leakage.The present development gives an insight into the effect of the distribution of bimetallic sites in denitrification. A highly-dispersed Pd-Cu bimetallic catalyst supported by titanium dioxide nanofibers (Pd-Cu/TiO2) was in situ fabricated by electrospinning and subsequent calcination and chemical reduction, and then applied in the catalytic reduction of water phase nitrate (NO3−) to nitrogen gas (N2). Compared with ex situ Pd-Cu impregnated catalyst, the in situ Pd-Cu/TiO2 nanofibers exhibited the high nitrate removal efficiency, selectivity and fast kinetics (about twice that of impregnated ones). These good catalytic performances are mainly benefited from increased active sites and raised ratio of nitrogen to hydrogen on them, which are brought about by the well-dispersed and closely connected Pd-Cu bimetallic nanoparticles in TiO2 nanofiber matrix. Moreover, the in situ nanofiber matrix provides a physical barrier to inhibit bimetallic nanoparticles movement, aggregation and leakage from the support into water, and hence significantly enhances the recyclability for nitrate reduction.Download high-res image (155KB)Download full-size image

•High cationic charge was achieved through co-electrospun nanofiberous membrane.•The maximum adsorption capacity toward PS and MB were 1180 and 1290 mg/g.•The separation factor of anionic to cationic dyes was as high as 970.•The membrane demonstrated excellent chemical stability in harsh environments.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.Download high-res image (283KB)Download full-size image

Porous carbonaceous materials are widely used as catalyst carriers to activate peroxymonosulfate (PMS) for catalytic oxidative degradation of organic pollutants. Herein, hierarchical structured ferro-cobalt alloyed crystals supported on nitrogen doped activated porous carbon fibers (FeCo2@APCFs) were prepared by a combination of multicomponent electrospinning, activation, and carbonization. Benefiting from the precursor design and activation process, the carbon fibers derived from a PAN/PBZ (polyacrylonitrile/polybenzoxazine) precursor exhibited a tunable porous structure with an ultrahigh specific surface area (SSA) and pore volume of 2085 m2 g−1 and 1.12 cm3 g−1, respectively. Most importantly, the FeCo2 crystals can be directly synthesized by carbonization at high temperature in a N2 flow with no other reducing gases. The as-prepared FeCo2@APCFs exhibited robust activation of PMS with reactive oxygen radicals (SO4˙−, ˙OH, and 1O2) for ultrafast removal of organic pollutants, as well as good stability and recyclability with high total organic carbon (TOC) removal. The catalyst suspended in aqueous solution after catalysis can be easily separated with an external magnet without tedious separation processes. This study is meaningful for the development of novel catalyst carriers or a fascinating strategy for wastewater treatment.

Herein, flexible and hierarchical porous catalytic carbon nanofibrous membranes (MnO/Co@SiO2-CNFMs) driven by gravity were prepared using a co-electrospinning technique and self-reduced pyrolysis. Benefiting from the active metals and precursor carrier design, the composite active MnO/Co crystals can be directly produced without any reducing gases and easily migrate to the carbon nanofiber surface during the carbonization process. Meanwhile, the silica nanoparticles (SiO2 NPs) doped in the carbon nanofibers (CNFs) can maintain the carbon nanofiber structure without obvious shrinkage as well as transmit and scatter the outer stress, which endowed the membrane with robust flexibility and mechanical strength. The as-prepared MnO/Co@SiO2-CNFMs exhibited a superhydrophilic surface with a water contact angle of 0°, fast water flux of 752 ± 28 L m−2 h−1, and prominent catalytic performance with a high degradation efficiency over 99.5% toward methylene blue (MeB). Furthermore, four typical refractory pollutants (phenol, bisphenol-S, chlorophenol and sulfamethoxazole) can also be efficiently degraded by the gravity driven MnO/Co@SiO2-CNFMs/PMS system. This study is meaningful for the development of novel catalytic membranes with high efficiency and low energy consumption for wastewater treatment.

Uniform α-Fe nanoparticle anchored hierarchical carbon nanofibres were prepared by PAN/FeCl3 co-electrospinning and self-reduced pyrolysis. Profiting from active zero-valent iron and high adsorption capacity, the composite nanofibres exhibited excellent activity, high stability and easy magnetic separation in the PMS activation for organic pollutant oxidative degradation.

ABSTRACTMixed matrix membranes (MMMs) were made by incorporating vinyltrimethoxysilane (VTMS)-modified Silicalite-1 zeolite nanoparticles (V-Silicalite-1 NPs) into fluorinated polybenzoxazine (F-PBZ) modified polydimethylsiloxane (PDMS) polymer through in situ polymerization method. The membrane morphology, surface wettability, and pervaporation performance were systematically investigated. The addition of F-PBZ into PDMS membranes resulted in substantially improved flux and marginal increase of separation factor, which is the result of higher free volume and higher hydrophobicity caused by the addition of F-PBZ. The modification of Silicalite-1 NPs improved the interfacial contact between zeolite crystals and polymer phase. The incorporation of hydrophobic V-Silicalite-1 zeolite NPs into the PDMS membranes led to much higher separation factor but reduced flux, which is the result of increased hydrophobicity and reduced free volume. The three-component MMMs with V-Silicalite-1 zeolite NPs in the F-PBZ fluorinated PDMS exhibited separation factor of 28.7 and flux of 0.207 kg m−2 h−1 for 5 wt % ethanol aqueous solution at 50 °C, while the pure PDMS membranes only had separation factor of 4.8 and flux of 0.088 kg m−2 h−1. The substantial increase of both flux and separation factor were attributed to the higher hydrophobicity and free volume caused by the incorporation of both hydrophobic zeolite crystals and F-PBZ polymer into the PDMS membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44753.

•A superior phosphate scavenger was designed deriving from La-MOF.•The adsorbent has a hierarchical structure of microsphere-nanorod-nanoparticle.•A high adsorption capacity and a high P/La ratio were obtained concurrently.•The adsorbent exhibits a much higher adsorption capacity of over 170 mg P/g.Excessive phosphate in water can cause severe water quality problems owing to its somatotrophic effect on microorganisms. Herein, a superstructural phosphate scavenger, La-MOF-500, composed of La2O2CO3, is rationally designed by derivation from lanthanum metal organic frameworks (La(1,3,5-BTC)(H2O)6) by calcination. La-MOF-500 has a hierarchical micro/nano structure of microsphere-nanorod-nanoparticle: urchin-like microsphere is comprised of many nanorods and the individual nanorod was formed by piling up plentiful thin nanoparticles. The hierarchical micro/nano structure provides La-MOF-500 with an intriguing phosphate capture capacity of 173.8 mg P/g and a high utilization of lanthanum active sites, simultaneously, which was a challenge in previous research. Moreover, La-MOF-500 exhibits a good tolerance of foreign species. Even in the water from Songhua River (China), La-MOF-500 can remove phosphate to be less than 10 μg P/L. This development is expected to be meaningful for practical water purification.Download high-res image (79KB)Download full-size image

•Nanostructured Pd/PPy composite paper is fabricated for hydrogen generation.•Broad pores constructed by rough fibers extend the paths for reactant diffusion.•Higher catalytic activity than most other Pd based film catalysts is achieved.•Ace stability and reproducibility are realized by immobilization of Pd by PPy.“Mass transfer in catalyst supports”and “reactive sites”are two critical factors for supported thin film catalysts. Based on such considerations, paper composed of cellulose fibers (CFs) is chosen as a competent nano-catalyst carrier because its broad porous structure is conducive to mass transfer. Then a facile aquatic synergistic synthesis is developed to decorate polypyrrole (PPy) encapsulated palladium nano-composites onto the CF paper structures. The pyrrole monomers (Py) reduce Pd2+ to Pd nanoparticles in aqueous solution, and meanwhile the Pd2+ initiates the polymerization of Py to PPy. In the as-prepared composite paper catalysts, the broad pores constructed by the microfibers facilitate the reactant diffusion and the Pd/PPy nanoparticles supported on the fibers provide more reactive sites for catalysis. As a result, the catalytic activity for hydrolysis of ammonia borane is improved. The H2 turnover frequency is 21.1 mol H2 mol Pd−1 min−1, surpassed most other Pd based film catalysts. Importantly, excellent stability and reproducibility are also realized by the immobilization of Pd NPs by PPy layers onto fibers.

A high-performance, cost-effective and spongeous adsorbent was rationally designed for Cr(VI) removal from aqueous solution based on PPy modified natural quasi two-dimensional (2D) structures. Core of corncobs, a kind of agricultural waste composed of quasi 2D sub-micro sheets, has a unique macroporous spongeous microstructure. In consideration of the unique chemical structure of polypyrrole (PPy) and microstructure of the natural sponge, we constructed the microstructured spongeous adsorbents. The PPy active layer provided reactive sizes to detoxifies Cr(VI) ions by ion-exchange. While the spongeous microstructure provided by the microsheets could enhance the adsorption performance by increasing active areas and facilitating the access of pollutants inside the adsorbents. Compared with artificial nano-powder adsorbents, CC–PPy displayed larger advantage in separation process and fabrication/operation cost. Compared with other bulk-style PPy composites, the adsorption capacity of CC–PPy was several times higher. In addition, the regeneration and stability of CC–PPy was outstanding with no loss in the adsorption to Cr(VI) even after 3 adsorption–desorption cycles. The present development provides a solution to design highly efficient and cost-effective water treatment agents.

La(OH)3 nanorods immobilized in polyacrylonitrile (PAN) nanofibers (PLNFs) were fabricated for the first time by electrospinning and a subsequent in situ surfactant-free precipitation method and then applied as a highly efficient phosphate scavenger to realize nutrient-starvation antibacteria for drinking water security. The immobilization by PAN nanofibers effectively facilitated the in situ formation of the aeolotropic and well-dispersed La(OH)3 nanostructures and, thus, rendered higher phosphate removal efficiency due to more exposed active sites for binding phosphate. The maximum phosphate capture capacity of La(OH)3 nanorods in PAN nanofibers was around 8 times that of the La(OH)3 nanocrystal fabricated by precipitation without PAN protection. Moreover, remarkably fast adsorption kinetics and high removal rate were observed toward low concentration phosphate due to the high activity of our materials, which can result in a stringent phosphate-deficient condition to kill microorganisms in water effectively. The present material is also capable of preventing sanitized water from recontamination by bacteria and keeping water biologically stable for drinking. Impressively, stabilized by PAN nanofibers, the La(OH)3 nanorods can be easily separated out after reactions and avoid leaking into water. The present development has great potential as a promising antimicrobial solution for practical drinking water security and treatment with a negligible environmental footprint.Keywords: antibacteria; drinking water security; electrospinning; La(OH)3; phosphate removal;

Conducting polymers-based gas sensors have attracted increasing research attention these years. The introduction of inorganic sensitizers (noble metals or inorganic semiconductors) within the conducting polymers-based gas sensors has been regarded as the generally effective route for further enhanced sensors. Here we demonstrate a novel route for highly-efficient conducting polymers-based gas sensors by introduction of polymeric sensitizers (polymeric adsorbent) within the conducting polymeric nanostructures to form one-dimensional polymeric adsorbent/conducting polymer core–shell nanocomposites, via electrospinning and solution-phase polymerization. The adsorption effect of the SPEEK toward NH3 can facilitate the mass diffusion of NH3 through the PPy layers, resulting in the enhanced sensing signals. On the basis of the SPEEK/PPy nanofibers, the sensors exhibit large gas responses, even when exposed to very low concentration of NH3 (20 ppb) at room temperature.Keywords: electrospinning; gas sensor; one-dimensional core−shell structure; polymeric sensitizer; polypyrrole; sulfonated poly(ether ether ketone);

Uniform α-Fe nanoparticle anchored hierarchical carbon nanofibres were prepared by PAN/FeCl3 co-electrospinning and self-reduced pyrolysis. Profiting from active zero-valent iron and high adsorption capacity, the composite nanofibres exhibited excellent activity, high stability and easy magnetic separation in the PMS activation for organic pollutant oxidative degradation.