Huai Ying Zhou

Preparation of Persimmon Tannins Immobilized on Collagen Adsorbent and Research on its Adsorption to Cr(VI)

Persimmon tannins (PT) were immobilized on a matrix of collagen fiber by cross-linking of glutaraldehyde. The adsorption behaviours to Cr (VI) on PT were investigated including the effects of initial pH, initial concentration of Cr (VI), temperature, adsorbent dosage, adsorption kinetics and the recycling performance of PT adsorbents. The results showed that pH value had a major influence in adsorption. PT showed a strong adsorbability to Cr (VI) in the pH range of 1.0 to 3.0, whereas the effect of temperature on the adsorption was comparatively weaker. The adsorption equilibrium could be well described by Freundlich equation. PT adsorption efficiency of Cr (VI) reached 98.04% and the maximum equilibrium adsorption capacity of Cr (VI) was up to 49.01 mg/g at 303 K with a pH value of 2.0, 100 mg/L of initial concentration of Cr (VI) and 0.1g of adsorbent dosage. The adsorption data could be well fitted by pseudo-second-order rate model. PT adsorbents were characterized by FTIR and EDS. The analysis indicated that the adsorption mechanism was mainly contributed by redox adsorption.

Synthesis and Activity of Ag-Doped Bi2WO6 Photocatalysts

Ag-doped Bi2WO6 photocatalysts were synthesized by hydrothermal method using from Bi (NO)3·5H2O, NH4VO3, and AgNO3 and further characterized by X-ray diffraction, Scanning electron microscopy, Energy dispersive X-ray detector (EDS) and UV-Vis diffusion reflectance spectra techniques. The photocatalytic activity of Ag-doped Bi2WO6 photocatalysts was evaluated by degrading RhB (10 mg/L) under visible light irradiation (λ > 420 nm). The results showed that in comparison with pure Bi2WO6 the photocatalytic activity of Ag-doped composite photocatalysts was improved significantly, and the degradation rate of RhB was increased about 26% when the Ag+ dopant concentration was 15%.

Microstructure and Magnetic Properties of RE2.28Fe13.58B1.14 Alloys

The rare-earth (RE) permanent magnets based on Nd2Fe14B with excellent magnetic properties have been widely used in industrial applications. In this work, the crystal structure, microstructure and magnetic properties of Nd2.28Fe13.58B1.14, Ce2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys prepared by arc-melting were investigated. The results show that all alloys are single phase with tetragonal Nd2Fe14B-type (space group P42/mnm). The Curie temperatures (Tc) of RE2.28Fe13.58B1.14 (RE=Nd, Ce, Pr) alloys are 583 K, 423 K and 557 K, respectively. On the other hand, the coercivities of Nd2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys are about 1.05 T and 1.23 T, respectively, while that of Ce2.28Fe13.58B1.14 alloy is only about 0.25 T due to the poor squareness of hysteresis loop. Meanwhile, the saturation magnetizations of Nd2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys are about 135 emu/g and 113 emu/g, respectively, while that of Ce2.28Fe13.58B1.14 alloy is about 97 emu/g. It was indicated that the Curie temperatures and magnetic properties of RE2.28Fe13.58B1.14 alloys with the same crystal structure are dependent on light rare earth elements.

Improved Dehydriding Properties of NaMgH3 Perovskite Hydride by Addition of Graphitic Carbon Nitride

NaMgH3 perovskite hydride and graphitic carbon nitride (g-C3N4) powder with multi-layer structure have been synthesized by high-energy ball-milling and heating-decomposition method respectively. In comparison with pristine NaMgH3 hydride, the as–milled NaMgH3+5wt.% g-C3N4 (NMH-5CN) composite presents better dehydriding kinetic properties and lower onset decomposition temperature. The onset decomposition temperature of NMH-5CN composite can be decreased about 87K, the hydrogen-desorbed amount is about 3.2 wt. % within 40min, and 1.4 wt. % within 10min at 638K, and the Kissinger analysis demonstrated that the activation energy (ΔE) of the first and second dehydrogenation step for NMH-5CN can be reduced about 40 kJ mol-1 and 22.4 kJ mol-1, respectively. The results suggest that g-C3N4 is an effective catalyst for the improvement of dehydriding properties of NaMgH3 perovskite hydride.

Electrochemical Performance of Spherical Li3V2(PO4)3/C Synthesized by Spray Drying Method

Spherical Li3V2(PO4)3/C cathode materials have been successfully synthesized by a spray drying method. The structure and morphology of the cathode materials are characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric (TG) analysis. The results show that synthesized monoclinic Li3V2(PO4)3 with high purities exhibits spherical morphology, in favor of enhancing the capacities and cycling stability of Li3V2(PO4)3/C cathode materials for lithium-ion battery. The Li3V2(PO4)3/C cathode materials sintered at 750 °C present best electrochemical performance among all the samples. It exhibits high initial discharge capacities of 99.2 mAhg-1 and capacity retention of 93.6% after 200 cycles at a rate of 1C within a voltage range of 3.0–4.3 V.

Thermodynamic Calculations of the Rare Earth Permanent Magnets: Fe-RE Binary Systems

As the key sub-binary systems in the rare-earth (RE) permanent magnetic materials with excellent magnetic properties (e.g. Nd-Fe-B, Sm-Fe-N magnets), the Fe-RE binary systems were investigated widely due to the industrial applications of permanent magnets. In this work, the experimental data of phase equilibria and thermodynamic properties of the Fe-RE binary systems (RE=La, Ce, Pr, Nd) in the published literature are reviewed firstly. Based on available phase equilibria data and thermodynamic data, the Fe-RE binary systems are assessed thermodynamically using the CALPHAD method. As a result, further experimental information and thermodynamic calculations will be both required in order to develop thermodynamic database of the RE-Fe-B ternary systems, which is very useful to study the relations between alloy composition, microstructure and magnetic properties of novel Nd-Fe-B-based permanent magnets.

Evaluation of Pulsed Laser Deposited Li4Ti5O12 Thin Film Anodes by CV and EIS

Li4Ti5O12 thin film anodes were prepared successfully using pulsed laser deposition technique. The thin films were characterized by X-ray diffraction and environmental scanning electron microscopy. The effects of thickness and scan rate on the electrochemical properties of Li4Ti5O12 thin film electrodes were discussed in detail. The thin film anodes deliver favorable capacity and excellent cycling performance. The discharge capacity maintains at 141 mAhg-1 after 20 cycles at 1C charge-discharge rate for the thin film anodes deposited for 20 minutes. The charge-transfer resistances were also investigated by electrochemical impedance spectroscopy.

Adsorption for Au3+ by Persimmon Tannins Immobilized on Collagen Fiber

A novel adsorbent which is effective to adsorb Au3+ was prepared using immobilized persimmon tannin (PT) on collagen fiber by glutaraldehyde crosslinking. The adsorption behaviour of this new adsorbent to Au3+ in aqueous solution was investigated. The effects of various factors such as initial solution pH, temperature, ionic strength and initial concentration of Au3+ on the influence of the adsorption process were studied. The equilibrium adsorption capacity reached 2347 mg/g at 323 K and pH value 2.0 when the initial concentration of Au3+ in aqueous solution was 500 mg/L. The immobilized PT was characterized by FT-IR, XRD and SEM. The results indicated that Au3+ changed to gold by oxidation adjacent phenol hydroxyl groups of persimmon tannin. Experiments also showed that adsorption isotherms of immobilized tannin for Au3+ could be described by Langmuir models. Immobilized PT adsorption provided a new way for the separation of the precious metal ions

Adsorption of In3+ from Aqueous Solutions by Persimmon Tannins-Immobilized Collagen Fiber

In the present work, a novel adsorbent to effectively adsorbed In3+ from an aqueous solution has been prepared by immobilizing persimmon tannin (PT) on collagen fiber. The adsorption capacities of In3+ on the immobilized PT were evaluated under various treatment conditions including the initial solution pH, solid-liquid ratio and temperature. The results showed that the effect of initial solution pH and solid-liquid ratio on the adsorption capacity were remarkable, while the influence of temperature was insignificant. The adsorption capacity reached 420 mg/g at 303 K and pH 5.0 when the initial concentration of In3+ was 100 mg/L and solid-liquid ratio was 0.2. The adsorption isothermal and kinetic data fitted best to the Freundlich model and the pseudo-second-order model, respectively.All these results indicated that adsorbent adsorbed efficiently and could be used as a low-cost alternative for the adsorption of In3+ in wastewater treatment.

Synthesis and Photocatalytic Activity of Ag-Doped BiVO4

Ag-doped BiVO4 semiconductor photocatalysts were synthesized via the one-step hydrothermal method. The microstructure and morphology of catalysts were characterized by using X-ray diffraction, Scanning electron microscopy, and Energy dispersive X-ray detector (EDS) and photocatalytic activities of BiVO4 catalysts with and without Ag doping were evaluated by degrading methylene blue (MB) under visible-light irradiation. UV-Vis absorption spectra were measured to evaulate the photocatalytic activity of the as-synthesized catalysts. The results suggested that Ag-doped BiVO4 with larger rod-like particle size but better crystallnity has the stronger UV absorption. In comparison with pure BiVO4, degradation rate of MB was increased about 18% in Ag-doped BiVO4 with the Ag+ dopant concentration of 15 mol%.