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Zhao B.,Tianjin Polytechnic University | Zhao B.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | Zhao B.,Peking University | Zhao B.,Key Laboratory of Water and Sediment science | And 5 more authors.
Journal of Hazardous Materials | Year: 2012

A simple point of use (POU) device based on the theory of Donnan dialysis was developed for the removal of arsenate (As(V)) in the present study. A commercial anion exchange membrane was used as a semipermeable barrier between the feed and stripping solution (As(V)-spiked groundwater and a 12gL -1 table salt solution, respectively). The proposed POU device could be operated 26 times before replacing the stripping solution. In each batch, approximately 80% of the arsenate anions were transported across the membrane within 24h, and the arsenic concentration of the stripping solution was finally more than 180 times greater than that of the treated water. Cations were well preserved in treated water; however, a slight increase in the sodium ion concentration was observed due to electrolyte leakage. Alternatively, the chloride ion concentration significantly increased at the expense of a loss of sulfate and bicarbonate. The quality of treated water was in compliance with drinking water standards. Membrane fouling was investigated, and a reduction in the As(V) removal rates was not observed when the membrane was used repeatedly. Our results showed that the proposed Donnan dialysis POU device could effectively remove arsenic from drinking water in rural areas in a sustainable manner. © 2012 Elsevier B.V.

Xue A.,Peking University | Xue A.,Key Laboratory of Water and Sediment science | Shen Z.-Z.,Peking University | Shen Z.-Z.,Key Laboratory of Water and Sediment science | And 4 more authors.
Journal of Hazardous Materials | Year: 2013

Conventional zerovalent iron (ZVI) technology has low arsenic removal efficiency because of the slow ZVI corrosion rate. In this study, microbial fuel cell (MFC)-zerovalent iron (MFC-ZVI) hybrid process has been constructed and used to remove arsenite (As(III)) from aqueous solutions. Our results indicate that the ZVI corrosion directly utilizes the low-voltage electricity generated by MFC in the hybrid process and both the ZVI corrosion rate and arsenic removal efficiency are therefore substantially increased. The resultant water qualities are compliant with the recommended standards of EPA and WHO. Compared to the ZVI process alone, the H2O2 generation rate and output are dramatically improved in MFC-ZVI hybrid process. Strong oxidants derived from H2O2 can rapidly oxidize As(III) into arsenate (As(V)), which helps to improve the As(III) removal efficiency. The distribution analysis of As and Fe indicates that the As/Fe molar ratio of the flocs in solution is much higher in the MFC-ZVI hybrid process. This phenomenon results from the different arsenic species and hydrous ferric oxides species in these two processes. In addition, the electrosorption effect in the MFC-ZVI hybrid process also contributed to the arsenic removal by concentrating As(V) in the vicinity of the iron electrode. © 2013.

Zhao H.,Peking University | Zhao H.,Key Laboratory of Water and Sediment science | Zhang Y.,Peking University | Zhang Y.,Key Laboratory of Water and Sediment science | And 6 more authors.
Environmental Science and Technology | Year: 2012

Electrochemical reduction of carbon dioxide (CO2) to useful chemical materials is of great significance to the virtuous cycle of CO 2. However, some problems such as high overpotential, high applied voltage, and high energy consumption exist in the course of the conventional electrochemical reduction process. This study presents a new CO2 reduction technique for targeted production of formic acid in a microbial electrolysis cell (MEC) driven by a microbial fuel cell (MFC). The multiwalled carbon nanotubes (MWCNT) and cobalt tetra-amino phthalocyanine (CoTAPc) composite modified electrode was fabricated by the layer-by-layer (LBL) self-assembly technique. The new electrodes significantly decreased the overpotential of CO2 reduction, and as cathode successfully reduced CO2 to formic acid (production rate of up to 21.0 ± 0.2 mg·L-1·h-1) in an MEC driven by a single MFC. Compared with the electrode modified by CoTAPc alone, the MWCNT/CoTAPc composite modified electrode could increase the current and formic acid production rate by approximately 20% and 100%, respectively. The Faraday efficiency for formic acid production depended on the cathode potential. The MWCNT/CoTAPc composite electrode reached the maximum Faraday efficiency at the cathode potential of ca. -0.5 V vs Ag/AgCl. Increasing the number of electrode modification layers favored the current and formic acid production rate. The production of formic acid was stable in the MFC-MEC system after multiple batches of CO2 electrolysis, and no significant change was observed on the performances of the modified electrode. The coupling of the catalytic electrode and the bioelectrochemical system realized the targeted reduction of CO2 in the absence of external energy input, providing a new way for CO2 capture and conversion. © 2012 American Chemical Society.

Wang L.,Tianjin Polytechnic University | Wang L.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | Zhang Z.,Tianjin Polytechnic University | Zhang Z.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | And 6 more authors.
Separation and Purification Technology | Year: 2013

The reduction of CO2 emission to the atmosphere is necessary with regard to the global warming mitigation. Gas absorption membrane (GAM) contactor for CO2 capture is an emerging technology and exhibits great advantages compared to conventional chemical CO2 absorption processes. In this study, to better understand the GAM process, especially its long-term performance for CO2 absorption, both polypropylene (PP) and polyvinylidene fluoride (PVDF) hollow fiber membrane contactors were investigated for a 30-day operation period. The CO2 flux and recovery declined with time for both PP and PVDF membrane systems and the situation was worse for PVDF membrane. Analysis of mass transfer resistance based on Wilson plot method suggested that after long-term operation the resistance for CO 2 intramembrane transport increased by 160% and 290% for PP and PVDF membrane systems, respectively. The significant increase in the membrane mass transfer resistance means the membrane has been wetted. The contact angle measurements indicated that the membrane hydrophobicity declined significantly for PP and PVDF after 30 days of operation. Scanning electron microscope and the overall membrane porosity analysis proved that the change of the membrane pore structure were responsible for the deterioration. After long-term contacting with MEA solution, physical or chemical dissolving of membrane surface occurred for both PP and PVDF. Some pinholes appeared on the outer surface of the PVDF membrane after use for 3 days, and both their number and size significantly increased after 30 days; however, in the case of PP membrane, the pores changed from originally a long and narrow shape to oval, and the pore size also became uneven. Therefore, the variation in physical and chemical membrane properties during the long-term run should be paid attention to in order to comprehensively evaluate the GAM contactor for CO2 absorption. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Guo J.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | Zhang J.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | Lv X.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes
Advanced Materials Research | Year: 2011

Hemodialysis is the main treatment of acute and chronic renal failure, and the selection of hemodialysis membrane materials is the key factor that determines the curative possibilities. By changing the membrane forming conditions, we have spun polyvinylidene fluoride(PVDF) hollow fiber membranes with the same inner diameters but different wall thicknesses. Via centrifugal moulding, we have also made membranes into dialyzers to study the mechanical performance of the membranes and the dialysis performance of the dialyzers. The results show that the mechanical performance meets the demand of dialysis. For the dialyzers with 30μm fiber walls, the clearance rates of urea and lysozyme are 90% and 75% respectively, and the rejection rate of bovine serum albumin(BSA)comes to 90% plus. The increase of the mass content of the dope solution polyethylene glycol (PEG) from 19% to 22% decreases the rejection rate of BSA.

Zhijiang C.,Tianjin Polytechnic University | Zhijiang C.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | Jianru J.,Tianjin Polytechnic University | Qing Z.,Tianjin Polytechnic University | Haizheng Y.,Tianjin Polytechnic University
RSC Advances | Year: 2015

Amidoxime surface-functionalized polyindole (ASFPI) nanofibers were prepared by electrospinning of chemically synthesized poly(5-cyanoindole) followed by surface modification. The as-prepared ASFPI nanofibers were characterized with FTIR, SEM, BET surface areas and water contact angle measurement. Meanwhile, the adsorption properties and mechanism of ASFPI nanofibers towards Pb(II) and Cd(II) in aqueous solution were mainly investigated by a batch method. It was found that ASFPI nanofibers showed a high affinity towards Pb(ii) and Cd(ii). The maximum adsorption capacities were found to be 307.44 and 108.49 mg g-1 for Pb(ii) and Cd(II), which are markedly high values compared to other fiber adsorbents reported. The adsorption isotherms were better fitted with the Langmuir model rather than Freundlich and Temkin models. The kinetics data analysis showed that the adsorption process could be described by a pseudo-second order kinetic model, suggesting a chemisorption process as the rate limiting step. Thermodynamic parameters revealed the spontaneity of the adsorption process and higher temperature favored adsorption. Regeneration tests showed that ASFPI nanofibers could be reused repetitively for 10 times with 80% of the initial adsorption capacity. © The Royal Society of Chemistry 2015.

Fu Z.,Tianjin Polytechnic University | Wang X.-Q.,Tianjin Polytechnic University | Wang J.,Tianjin Polytechnic University | Cheng B.-W.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes
Gongneng Cailiao/Journal of Functional Materials | Year: 2014

Li-rich layered cathode material, LiNi0.5Mn0.5O2 and Li1.2Ni0.3Mn0.5O2 were synthesized via a solution method. The structure and morphology of the prepared materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM). Galvanostatic charge/discharge studies demonstrated the electrochemical performance of two materials. It was found that the material LiNi0.5Mn0.5O2 delivers initial discharge capacity of 125.6 mAh/g and retains a reversible capacity of 111.2 mAh/g after 30 cycles with a capacity retention of 96.2%. While the sample Li1.2Ni0.3Mn0.5O2 exhibited not only a higher discharge capacity of 187.2 mAh/g, but also excellent cycling performance with a capacity retention of over 98.6% after 30 cycles. In addition, the Li-rich Li1.2Ni0.3Mn0.5O2 shows better rate capability.

Zang H.,Tianjin Polytechnic University | Su Q.,Tianjin Polytechnic University | Guo S.,Tianjin Polytechnic University | Mo Y.,Tianjin Polytechnic University | Cheng B.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes
Chinese Journal of Chemistry | Year: 2011

A new class of pyrazolone derivatives has been isolated in good to excellent yields from the 2 : 1 condensation reaction between 3-methyl-1-phenyl-5-pyrazolone and arylaldehydes in the presence of ionic liquid [HMIM]HSO 4. The compounds were characterised by their IR, NMR spectra, MS and elemental analyses. The important features of the methodology are a wide application range of substrates, higher yields and shorter reaction time. © 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang X.,Tianjin Polytechnic University | Wang J.,Tianjin Polytechnic University | Wu J.,Harbin Institute of Technology | Cheng B.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | And 2 more authors.
Ionics | Year: 2015

Mg-doped spinel LiMg0.05Mn1.95O4 was synthesized and coated with three types of Li-containing manganese oxides (Li2Mn4O9, Li4Mn5O12, and LiNi0.5Mn1.5O4) to improve the cycling properties at room temperature and at 50 °C via a coprecipitation method. The as-prepared spinels were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma (ICP), and electrochemical tests. The results indicate that all the coated samples show enhanced electrochemical performance including higher initial charge-discharge capacities and more stable cycling properties as well as improved coulombic efficiency. Especially, the LiNi0.5Mn1.5O4-coated sample delivers the highest initial discharge capacity of 129 mAh/g with capacity retention of 82.5 % as well as the best coulombic efficiency of 92.1 %. This improved performance could be attributed to the enhanced electrochemical kinetics by successful surface modification of spinels with Li-containing manganese oxides via coprecipitation method. © 2015, Springer-Verlag Berlin Heidelberg.

Cai Z.,Tianjin Polytechnic University | Cai Z.,State Key Laboratory of Hollow Fiber Membrane Materials and Processes | Guo J.,Tianjin Polytechnic University | Yang H.,Tianjin Polytechnic University | Xu Y.,Tianjin Polytechnic University
Journal of Power Sources | Year: 2015

(Chemical Equation Presented). This study aims to develop an aqueous zinc/electrospun poly(5-cyanoindole) fibers secondary battery system. Zn foil and ZnCl2 are used as anode active materials and the electrolytic solution, respectively. Poly(5-cyanoindole) synthesized by chemical oxidation is electrospun into fibers and used as cathode active materials. FTIR and NMR test are carried out to investigate the chemical structure of poly(5-cyanoindole). Surface properties of electrospun poly(5-cyanoindole) fi bers are studied by SEM, TEM, and BET. The performance of zinc/electrospun poly(5-cyanoindole) fibers battery system is evaluated in term of electrical conductivity, cyclic voltammogram, electrochemical impedance spectroscopy, discharge capacity and durability test. The cell achieves 2.0 V electromotive force with about 107-61 Ah Kg-1 discharge capacity at 0.2C-10C rate. At 800th cycle, the discharge capacity remains 80-57 Ah Kg-1 at 0.2C-2C rate, which is about 75-63% of the maximum discharge capacity. These results indicate that the cell has very excellent cyclic properties as well as fast charge/discharge properties. Electrospun poly(5-cyanoindole) fibers have been proved to be a better candidate than polyindole powder as cathode material in zinc/polymer battery. © 2014 Elsevier B.V. All rights reserved.

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