Zhong Min Wang

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.

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.

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.

Influence of Temperature on Self-Discharge and High-Rate Discharge Characteristics of La-Rich AB5-Based MH Alloy Electrode

The influence of temperature on self-discharge and high-rate discharge characteristics of MmNi3.65(CoAlMn)1.35 alloy electrode has been investigated by way of simulated battery tests. Self-discharge behaviors of the MH electrode were measured using two methods: continuous mode self-discharge and step mode self-discharge. The results indicate that both reversible and irreversible capacity loss of MH electrode are mainly affected by temperature and storage time. When tested at 323K, the gross capacity loss after storage for 4 days is 30.88%, 15.02% at 273K and 20.09% at 303K, respectively. SEM analysis has shown that some needle corrosion products are formed on the surface of MH electrode, especially following storage at high temperature. The efficiency of high-rate discharge process is related closely to its discharge current density (DCD) adopted in tests, discharged capacities decreased with increasing DCD, and the electrode performed good high-rate discharge behavior at 303 K. Cyclic voltammetry (CV) analysis has indicated that near linear relationships between Ip and Scan rate (v) have been observed in the three temperature cases. The calculated values of hydrogen diffusion coefficient (D) within the electrode, are 1.479×10-8 cm2 / s at 273K, 2.437×10-8 cm2 / s at 303K, and 3.156×10-8 cm2 / s at 323K, respectively.

Synthesis and Electrochemical Performance of Tin-Copper Nanocomposites as a Superior Anode for Lithium-Ion Batteries

The Sn–Cu nanocomposites composing of Sn, Cu6Sn5, Cu3Sn and SnO2 are synthesized by a facile precipitation method. Their morphologies and structures are characterized using X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution TEM. The electrochemical properties are investigated by charge–discharge testing, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The sample with a Sn/Cu ratio of 5:3 delivers good cycling stability. The discharge specific capacity is 447.5 mAhg-1 after 70 cycles at a current density of 100 mAg-1 and the coulombic efficiency is beyond 95%. The superior rate and cycling performance of Sn–Cu nanocomposites are also demonstrated, which may be rooted in their nanostructure and phase composition.

Microstructure and Hydrogen Storage Properties of Ti-V-Fe Alloys

Microstructure, hydrogen storage properties and thermal stabilities of V-Ti-Fe alloys prepared by arc-melting were studied in this work. It was confirmed that V60Ti30Fe10, V70Ti20Fe10 and V80Ti10Fe10 alloys are a body-centered cubic (bcc) single phase, while V75Ti10Fe15 alloy consists of the bcc main phase and C14-typed Laves secondary phase. Experimental results show that the V80Ti10Fe10 alloy reached the largest hydrogen absorption capacities which were about 1.9 wt.% and 1.62 wt.% at 423 K and 473 K, while V75Ti10Fe15 alloy with C14-typed Laves phase showed better hydrogen desorption capacities with 1.31 wt.% at 423 K and 1.35 wt.% at 473 K, respectively. In addition, the DSC measurements indicate that the thermal stability of V75Ti10Fe15 alloy with C14-typed Laves phase decreased, which is very beneficial to the improvement of dehydrogenation rate in the alloy.

Effect of Surfactants on Morphology and Luminescent Properties of YAG:Ce Phosphors

Using anionic surfactant sodium dodecylsulfate (SDS), cationic surfactant cetyltrimethylammonium bromide (CTAB) and nonionic surfactant polyethylene glycol 20000 (PEG20000) and glyceryl monostearate (monostearin) respectively, Ce-doped Y3Al5O12 (YAG:Ce3+(6%)) yellow phosphors were prepared by a combination method of high energy ball milling and solid state reaction. The effects of surfactant type on structure, morphology and luminescence properties were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and fluorescence spectrometer. The results showed that the crystal structure of YAG:Ce3+ phosphors were not changed with the introduction of surfactants,but their morphology was greatly influenced. The maximum PL intensity was obtained for the nonionic surfactant PEG20000 due to the more uniform morphology and size as well as more homogeneous distribution of particles. Also, the results demonstrated that surfactant concentration had a vital effect on morphology and fluorescent properties of the phosphors,and the optimum amount of surfactant is 10 wt%.