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Zhang Y.,Tianjin Polytechnic University | Zhang Y.,State Key Laboratory of Separation Membranes and Membrane Processes | Wang L.,State Key Laboratory of Separation Membranes and Membrane Processes | Wang L.,Tianjin Polytechnic University | And 2 more authors.
Nano-Structures and Nano-Objects | Year: 2016

Well-defined three-dimensional (3D) hierarchical flowerlike calcium molybdate (CaMoO4) microspheres were successfully synthesized via a facile ultrasound-assisted ethylenediaminetetraacetic acid (EDTA) chelation process. The structure and morphology were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). Time-dependent experiments with appropriate intervals have clearly disclosed that the self-assembly process of 3D flowerlike CaMoO4 microspheres is governed by a nucleation-dissolution-recrystallization growth mechanism. Moreover, the nitrogen adsorption-desorption isotherm indicated the presence of mesoporosity in the product. The room temperature photoluminescence (PL) properties of the products were then studied using a spectrophotometer and the samples exhibited green emission peaks centered around 470 nm, 485 nm and 493 nm with 280 nm excitation wavelength. © 2016 Elsevier B.V. All rights reserved. Source


Kang W.,Tianjin Polytechnic University | Li F.,Tianjin Polytechnic University | Zhao Y.,State Key Laboratory of Separation Membranes and Membrane Processes | Qiao C.,Tianjin Polytechnic University | And 2 more authors.
RSC Advances | Year: 2016

Novel porous polytetrafluoroethylene (PTFE) nanofiber membranes containing Fe2O3 (Fe2O3/PTFE), used as a heterogeneous catalyst, were prepared via a three-step method by electrospinning, immersion and calcination. The morphology and structure of porous Fe2O3/PTFE were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer (XRD). The effects of the thickness of the as-spun nanofiber membrane, the immersion time and impregnating solution concentration on the content of Fe2O3 which was the active component were discussed. The degradation of Acid Red with hydrogen peroxide catalyzed by the porous Fe2O3/PTFE under UV irradiation was investigated. UV-vis and ESR techniques provided an insight into the nature of the degradation products and the formed active species. The results showed that Fe2O3 was successfully supported on the surface of porous PTFE nanofibers. The porous Fe2O3/PTFE nanofiber membrane prepared under the optimized parameters possessed high photocatalytic activity without any dye adsorption and could be recycled by simple filtration. © The Royal Society of Chemistry 2016. Source


Wang W.,Tianjin Polytechnic University | Wang W.,State Key Laboratory of Separation Membranes and Membrane Processes | Zhang J.,Tianjin Polytechnic University | Zhang Y.-F.,Tianjin Polytechnic University | Zhang Y.-F.,State Key Laboratory of Separation Membranes and Membrane Processes
Acta Polymerica Sinica | Year: 2016

With hydroxyl multi-walled carbon nanotubes (MWCNTs-OH) as carbonous fillers the high performance PVDF hollow fiber ultrafiltration membranes modified by MWCNTs-OH were prepared by the nonsolvent induced phase inversion process. Adding MWCNTs-OH into N, N-dimethyl acetamide (DMAC) solvent with ultrasonic treatment could strengthen their dispersion, and produce uniform casting membrane solution. The morphology and performances of modified membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic contact angle (DCA) and mechanical properties tests. The effects of MWCNTs-OH on the water flux and rejection as well as mechanical properties of the resulted hollow fiber membranes were investigated. The results showed that the water flux increased from 376. 4 L/m2h to 510. 9 L/m2h, while the rejection stabilized around 95. 0% as the MWCNTs-OH loading increased from 0 to 0. 09 wt%. The tensile strength and elongation at break increased from 1. 68 to 2. 42 MPa and 44. 18% to 79. 18%, respectively. The SEM and TEM images indicated that MWCNTs-OH were easy to reunite in the matrix along with the increase of contents of MWCNTs over 0. 09 wt%, resulting in the decrease of the membrane tensile strength and water flux. The crystal form of the hollow fiber membranes changed little with the addition of MWCNTs-OH which was evidenced by the analysis of Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. Source


Hu M.,Tianjin Polytechnic University | Kang W.,Tianjin Polytechnic University | Kang W.,State Key Laboratory of Separation Membranes and Membrane Processes | Cheng B.,Tianjin Polytechnic University | And 4 more authors.
Microchimica Acta | Year: 2016

A highly sensitive and fast sensor for gaseous hydrogen chloride (HCl) is described. It is based on the use of the optical probe 5,10,15,20-tetraphenylporphyrin contained in a poly(lactic acid) nanoporous fiber membrane that was fabricated via electrospinning. With its porous structure, the sensor overcomes the slow gas absorption and diffusion of other sensing materials. Field emission SEM was employed to characterize the morphology of the sensing membrane. The exposure to HCl gas causes a color change from pink to green that is due to the protonation of the central nitrogen atoms of the porphyrin, and fluorescence is quenched. The largest increase in absorbance occurs at 442 nm. HCl gas can be detected in this way even at sub-ppm levels. The detection limit is 34 ppb, and the response time is as short as 5 s. The sensor is highly stable after ten cycles of tracing HCl gas and recovery, and response is fully reversible. [Figure not available: see fulltext.] © 2016, Springer-Verlag Wien. Source


Li F.,Tianjin Polytechnic University | Kang W.,Tianjin Polytechnic University | Kang W.,State Key Laboratory of Separation Membranes and Membrane Processes | Cheng B.,Tianjin Polytechnic University | And 2 more authors.
Catalysis Communications | Year: 2015

A novel carbon nanofiber containing silver nanoparticles (NPs) with hollow structure was fabricated via co-electrospinning and in situ reduction. The hollow structure avoided the waste of silver NPs embedded in the nanofibers while ensuring high specific surface area. The formation of silver NPs was confirmed by Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalytic behavior of the nanofibers obtained to the reduction of methylene blue with NaBH4 was tracked by UV-visible spectroscopy. The results showed that carbon nanofibers containing silver NPs with hollow structure possessed significant catalytic properties. © 2015 Elsevier B.V. All rights reserved. Source

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