Advanced Materials Research Vols. 391-392

Abstract: Flake silver powder has attracted tremendous interesting due to its specially electrical and optical properties. Chemical reduction method with the advantages of reaction conditions easily controlled and mass production is widely used to prepare flake silver particles. In order to more easily prepare flake silver particles, the generation mechanism of flake silver particles is studied by analyzing the impacts of reaction conditions, such as pH value, kinds of silver seeds, kind of surfactant and concentration of raw material. The results show that flake silver particles can be prepared through controlling reaction conditions. Some problems existing in the preparation of flake silver particles are put forward, and future research directions are also proposed.

Abstract: The doped and undoped LiFePO₄/C samples are prepared by two-step solid-state reaction. The X Ray Diffraction (XRD) results indicate that metal ions are successfully doped in LiFePO4 without any unexpected phase. The Scanning Electron Microscope (SEM) shows that the particle morphologies of samples are near-spherical with about 200-300nm size which can be observed in all samples. The electrochemical tests indicate that doping oversize ions will increase electrode polarization. The limitation of the Li+ migration is intensified by doping metal ions with high valence. LiFePO₄/C samples doped with Mn2+ and Ti⁴⁺ behave better at low temperature, especially the one doped with Ti⁴⁺. Battery with this Ti⁴⁺ doped material can yield 77mAhg-1 when discharge at -20°C and 0.5C, about 26mAhg-1 higher than the undoped one.

Abstract: This study used distillation residue obtained from bio-refinery process of corn starch and glycerol as a plasticizer to prepare thermoplastic starch (TPS). Various weight ratios of distillation residue and glycerol was investigated, HPLC method was used to analysis the components of the distillation residue. The composition and structure of TPS were evaluated by FTIR, XRD and TGA. The results indicated that with the addition of mixed plasticizers, the structure of TPS was changed obviously from a crystal state to an amorphous one with an increasing thermal stability of TPS. The better TPS structure can be obtained when the weight ratio of distillation and glycerol is 3:7.

Abstract: Adsorptions of organic sulfur compounds thiophene was carried out using metal ion-exchanged Y-zeolites. Na-Yzeolites exchanged with Ag⁺, La³⁺, Cu²⁺, Ni²⁺, Bi³⁺ ions were prepared by liquid ion exchange method. Ag⁺ and La³⁺ ions modified Yzeolites showed markedly high adsorptive capacities for Thiophene. The sulfur uptake increased in the order of Bi-Yzeolite < Ni-Yzeolite < CuY-zeolite < AgY-zeolite < LaY-zeolite for thiophene. The mole ratios of TP/Ag and TP/La were 0.098 and 0.071, respectively.

Abstract: Xylan-rich Hemicelluloses (XH) isolated from wheat straw were converted to functional biopolymers by modification using succinic anhydride (SA) as reactant without catalyst in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid. The reaction was performed under various conditions such as different temperatures, different times, and the different amounts of SA, and the effect of reaction factors on the degree substitution (DS) of products were discussed. The product had the maximum DS of 1.80. The structure of modified hemicellulosic derivatives (MD) was actually confirmed by ¹³C NMR spectroscopy. The thermal behavior of MD was monitored by means of thermogravimetry (TG) and differential thermal analysis (DTA), and the thermal stability of MD was lower than XH.

Abstract: The electrodeoxidation of Dy₂O₃ for preparing metal Dy in CaCl₂ melt was studied by cyclic voltammetry, constant potential electrolysis techniques and thermodynamics analysis. Two electrodes system was employed during measuring cyclic voltammetry. Only one cathodic current peak(at about -1.75V ) was discovered before the decomposition of CaCl₂ which corresponded to the electrodeoxidation of Dy₂O₃ in the cyclic voltammograms in molten CaCl₂ at 850°C. The validity of the cyclic voltammograms was further confirmed by thermodynamics analysis and the CO₂、CO anodic gas detected. In constant potential electrolysis products there were no other intermediates except Dy₂O₃ and Dy observed by XRD. And the results confirmed the following electrodeoxidation sequence: Dy₂O₃→Dy.

Abstract: La_0.85K_0.15CoO₃ perovskite-tpye catalyst was prepared by a sol-gel method and characterized by catalytic activity analysis to study the effect of NO and O₂ on the combustion of soot. The catalytic activity of La_0.85K_0.15CoO₃ Catalyst was promoted with NO. No matter lean or rich oxygen conditions, the La_0.85K_0.15CoO₃catalyst could ignite soot at low temperature. The results of XRD and FT-IR showed that La_0.85K_0.15CoO₃ catalyst has the desired perovskite-type structure, ABO₃.

Abstract: AC/TiO₂ composite particles were prepared by sol-gel method in normal temperature. Three kinds of particles were obtained by adding Phytic Acid (ab. PA), Benzoyltrifluoroacetone (ab. BTA) and SnCl4 during the preparation. The photo catalytic activity and adsorptive capability of different particles were compared. Raman analysis showed TiO₂ grain on the surface of the AC carrier was anatase. FE-SEM photos showed particles with PA were homogeneously coated by TiO₂, but more fine TiO₂ particles were formed with BTA. The results showed that the adding of PA and BTA helped to get fine grains. The degradation ratio of the TNT solution showed that the photo catalyses activity and adsorptive capability of all composite particles were higher than that of single AC, and the accumulated degradation ratio of TNT solution reached 99.3 % (repeated by 20 times). The degradation of single AC to TNT solution is thought mainly by physical adsorption, but for other composite particles the degradation is by both of the adsorption and photo catalysis. The interface between AC carrier and TiO₂ crystal may be affected by PA or BTA, and helping to form synergic effect of AC and TiO₂.

Abstract: The adsorbent was prepared from Grapefruit peel by activation with ZnCl2. Grapefruit peel adsorbent (GPA) was employed to be as adsorbent to remove Pb(Ⅱ) in wastewater. The affecting factors on the adsorption of Pb(Ⅱ)from aqueous solution with GPA, such as solution pH, contact time, GPA dosage, initial Pb(Ⅱ) concentration, and reaction temperature were investigated. Adsorption kinetics and adsorption mechanism were investigated also. The results showed that the factors mentioned above have remarkably influence on adsorption of Pb(Ⅱ) ions onto GPA. The suitable conditions for the adsorption conditions were as following: solution pH, 5.3~6.5; contact time, 1.5 hours; GPA dosage, 10 g/L; initial Pb(Ⅱ) ion concentration, 100 mg/L; temperature, 30°C. Under the suitable conditions, the removal rate of Pb(Ⅱ) was more than 90% and the sorption capacities of the GPA for Pb(Ⅱ) were 12.73mg/g. Adsorption kinetics of Pb(Ⅱ) ions onto GPA obeyed pseudo-second-order equation. The isothermal adsorption can be described well by Langmuir, Freundlich and Temkin models, and the Freundlich model was the best.

Abstract: Li(Ni_1/3Co_1/3Mn_1/3)O₂ material with high rate capability was synthesized by a novel gel-combustion method using polyvinylpyrrolidone as a polymer chelating agent and a fuel. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to study the structure, morphology and element distribution of the Li(Ni_1/3Co_1/3Mn_1/3)O₂ material. XRD analysis showed that all samples were α-NaFeO₂ structure and Li(Ni_1/3Co_1/3Mn_1/3)O₂ prepared at 900 °C had the highest c/a of 4.977 indicating the highest layered-ness. EDS scan demonstrated that the precursor was homogeneous. SEM images indicated all samples were well crystallized. Charge and discharge tests showed all samples had good rate capability. Among them, Li(Ni_1/3Co_1/3Mn_1/3)O₂ prepared at 900 °C had the highest capacity and the best rate capability. It delivered 162.1 mAh•g⁻¹ at 0.25 C between 2.5 and 4.3 V and the capacity retention was about 81% compared to that of 0.25C rate.