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Ruan Y.,State Key Laboratory of Separation Membranes and Membrane Processes | Ruan Y.,Tianjin Polytechnic University | Ruan Y.,Lawrence Berkeley National Laboratory | Song S.,Tianjin Polytechnic University | And 6 more authors.
Ceramics International | Year: 2017

Sodium zirconium silicon phosphorus with the composition of Na3Zr2Si2PO12 (NZSP) was prepared by a facile solid state reaction method. The effects of the calcination temperature and rare earth element substitution on the structure and ionic conductivity of the NZSP material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and AC impedance measurement. The results show that the microstructure and ionic inductivity of the NZSP was strongly affected by the aliovalent substitution of Zr4+ ions in NZSP with rare earth metal of La3+, Nd3+ and Y3+. At room temperature, the optimum bulk and total ionic conductivity of the pure NZSP solid electrolyte sintered under different conditions were 6.77×10−4 and 4.56×10−4 S cm−1, respectively. Substitution of La3+, Nd3+ and Y3+ in place of Zr4+ exhibited higher bulk conductivity compared with that of pure NZSP. Maximum bulk and ionic conductivity value of 1.43×10−3 and 1.10×10−3 S cm−1 at room temperature were obtained by Na3+xZr1.9La0.1Si2PO12 sample. The charge imbalance created by aliovalent substitution improves the mobility of Na+ ions in the lattice, which leads to increase in the conductivity. AC impedance results indicated that the total ionic conductivity strongly depends on the substitution element and the feature of the grain boundary. © 2017 Elsevier Ltd and Techna Group S.r.l.


Zhang Z.,State Key Laboratory of Separation Membranes and Membrane Processes | Zhang Z.,Tianjin Polytechnic University | Wu X.,Tianjin University | Wang L.,State Key Laboratory of Separation Membranes and Membrane Processes | And 6 more authors.
RSC Advances | Year: 2017

As an emerging technology, membrane gas absorption (MGA) contactors for carbon dioxide (CO2) capture exhibit great advantages compared to conventional chemical CO2 absorption processes. However, the decline in membrane flux, caused by the membrane's wetting, is a serious technical problem. In this study, to better understand the wetting mechanism of a polyvinylidene fluoride (PVDF) hollow fiber membrane in an immersed membrane contactor for CO2 capture, a 30 day operation of CO2 absorption was conducted, in which, 2 M monoethanolamine (MEA) solution and deionized water were used as the absorbents. The results showed that the presence of MEA in the absorbent solution aggravated the wetting phenomenon, thus significantly decreasing the membrane flux and membrane hydrophobicity. X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-infrared spectroscopy (ATR-IR) analyses for the wetted membranes proved that no chemical reactions occurred between the MEA and the membrane. Furthermore, no hydrophobic components of the wetted membrane dissolved in the MEA solution. Instead, the presence of MEA was observed in the cross-linked network of the membrane wetted by the MEA absorbent. Field emission scanning electron microscope (FE-SEM) images of the outer surfaces of the wetted membranes suggested that the membrane morphologies changed and the membrane walls thickened, especially for the membrane wetted by the MEA absorbent. Both the presence of MEA molecules in the cross-linked network of the wetted membrane and the thickening of the membrane wall were important characteristics of membrane swelling. The changes in mechanical strengths of the wetted membranes also testified that membrane swelling occurred. Based on the above results, it was concluded that the membrane swelling caused the membrane wetting in the immersed PVDF membrane contactor for CO2 capture, and the presence of MEA in the absorbent further aggravated the process of membrane swelling. © The Royal Society of Chemistry.


Lu Y.,State Key Laboratory of Separation Membranes and Membrane Processes | Xu N.,State Key Laboratory of Separation Membranes and Membrane Processes | Lv Y.,State Key Laboratory of Separation Membranes and Membrane Processes | Feng Y.,State Key Laboratory of Separation Membranes and Membrane Processes
Journal of Applied Polymer Science | Year: 2017

The Fenton method has been used to remedy dye wastewater because hydroxyl radicals generated from the Fenton reaction can oxidize the dye into small molecules. In comparison with a homogeneous reaction, a heterogeneous reaction with a solid material as a catalyst is a more appropriate alternative for dye wastewater treatment. Because of the large specific surface area and excellent applicability, a novel fibrous material based on a combination of functional polymer with iron ions was designed in this study and used as a heterogeneous catalyst for dye wastewater treatment by the Fenton method. The fibrous material was found to have good catalytic activity for the oxidative decomposition of a variety of dyes and good reusability; additionally, the fibrous material could remove the dye to a greater extent and leave fewer iron ions in the treated wastewater than a homogeneous Fenton catalyst such as iron(II) chloride (FeCl2). What is more, the fibrous material could adsorb the residual iron ions from the treated wastewater and make these iron ions take part in the next catalyzation. The previous results make us believe that the prepared fibrous material might be used to create a green approach for dye wastewater treatment. © 2017 Wiley Periodicals, Inc.


Wang M.,State Key Laboratory of Separation Membranes and Membrane Processes | Song J.,State Key Laboratory of Separation Membranes and Membrane Processes | Li Y.,State Key Laboratory of Separation Membranes and Membrane Processes | Chu Y.,Tianjin Key Laboratory of Advanced Fibers and Energy StorageTianjin Polytechnic UniversityTianjin300387 China
AIChE Journal | Year: 2017

Nickel is a cheaper metallic material compared to palladium membranes for H2 separation. In this work, metallic Ni hollow fiber membranes were fabricated by a combined phase inversion and atmospheric sintering method. The morphology and membrane thickness of the hollow fibers was tuned by varying the spinning parameters like bore liquid flow rate and air gap distance. H2 permeation through the Ni hollow fibers with N2 as the sweep gas was measured under various operating conditions. A rigorous model considering temperature profiles was developed to fit the experimental data. The results show that the hydrogen permeation flux can be well described by using the Sieverts' equation, implying that the membrane bulk diffusion is still the rate-limiting step. The hydrogen separation rate in the Ni hollow fiber module can be improved by 4-8% when switching the co-current flow to the countercurrent flow operation. © 2017 American Institute of Chemical Engineers.


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.


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.


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.


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.


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.


Tao L.,State Key Laboratory of Separation Membranes and Membrane Processes | Zhao Y.,State Key Laboratory of Separation Membranes and Membrane Processes | Kang W.,State Key Laboratory of Separation Membranes and Membrane Processes | Cheng B.,State Key Laboratory of Separation Membranes and Membrane Processes | Qiao C.,State Key Laboratory of Separation Membranes and Membrane Processes
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2016

Polytetrafluoroethylene (PTFE) nanofibers were prepared by an electrostatic spinning technology. Titanium dioxide (TiO2) particles were loaded on the PTFE nanofibers via dipping and sintering. The morphology and structure of the photocatalyst film were characterized. Effects of reacting conditions of the TiO2/PTFE superfine-fiber film on the photocatalytic degradation of methylene blue under UV-Vis light irradiation were investigated. In addition, the recycling utilization of load type TiO2 light catalyst was also discussed. The result show that the TiO2(as anatase)/PTFE nanofiber photocatalyst film was obtained after calcination at 450℃. Under the violet light (300 W, 365 nm) irradiation, when irradiation distance is 30 cm and after irradiation for 55 min, the TiO2/PTFE superfine-fiber film is prepared by dipping for 5 h. Its degradation rate for methylene blue with initial concentration of 5 mg/L and volume of 100 mL is 99%. The degradation efficiency of methylene blue is still 46% after recycling for 5 times, indicating that the recycling utilization rate is greater. © 2016, Editorial Department of Journal of the Chinese Ceramic Society. All right reserved.

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