Ammonium Metavanadate Fabricated by Selective Precipitation of Impurity Chemicals on Inorganic Flocculants

High purity ammonium metavanadate(NH_(4)VO_(3))is the most vital chemical to produce V2O5,VO2,VN alloy,VFe alloy and VOSO4,which have some prospective applications for high strength steel,smart window,infrared detector and imaging,large scale energy storage system.NH_(4)VO_(3)is usually produced by spontaneous crystallization from the aqueous solution due to its sharp dependence of solubility on the temperature.However,hazardous chemicals in industrial effluent,include phosphorate,silicate and arsenate,causing severe damage to the environment.In this work,these impurities are selectively precipitated onto inorganic flocculants,while the vanadate dissolved in an aqueous solution keeps almost undisturbed.Therefore,high purity NH_(4)VO_(3)is produced by the crystallization from the purified solution.By screening various flocculants and precipitating parameters,polyaluminum sulfate with an optimal amount of 50 g/L,is demonstrated to selectively remove phosphorate,silicate and arsenate,corresponding to the removing efficiency of 93.39%,97.11%and 88.31%,respectively.NH_(4)VO_(3)from the purified solution holds a purity of 99.21%,in comparison with 98.33%in the product from the crude solution.This purifying technology cannot only produce NH_(4)VO_(3)with high added value,but also reduce the environmental pollution of waste liquid.

Optimization of preparing V_2O_5 by calcination from ammonium metavanadate using response surface methodology

Parameters of technique to prepare vanadium pentoxide by calcination from ammonium metavanadate were optimized using central composite design of response surface methodology. A quadratic equation model for decomposition rate was built and effects of main factors and their corresponding relationships were obtained. The results of the statistical analysis show that the decomposition rate of ammonium metavanadate is significantly affected by calcination temperature and calcination time. The optimized calcination conditions are as follows： calcination temperature 669.71 K, calcination time 35.9 min and sample mass 4.25 g. The decomposition rate of ammonium metavanadate is 99.71%,which coincides well with experimental value of 99.27% under the optimized conditions, suggesting that regressive equation fits the decomposition rates perfectly. XRD reveals that it is feasible to prepare the V2O5 by calcination from ammonium metavanadate using response surface methodology.

Ammonium metavanadate:A novel catalyst for synthesis of 2-substituted benzimidazole derivatives

Ammonium metavanadate （10 mol%） was found to be a useful catalyst for the synthesis of various 2-substituted aryl benzimidazoles. It was used as an oxidizing agent for the condensation of o-phenylenediamine with different substituted aryl aldehydes at room temperature in ethanol. The method was proved to be simple, convenient and the product was isolated with good yields （79-91%）.

Role of reactive oxygen species in the antiproliferative effects of metavanadate on human prostate cancer DU145 cells

In the present study, the effects of metavanadate on the human prostate cancer cell line DU145 and the underlying mechanism were investigated. The results showed that metavanadate can cause cell cycle arrest at G2/M phase which was evidenced by cell cycle analysis and the increased phosphorylation of Cdc2 at its inactive Tyr-15 site. In addition, the results showed that metavanadate can induce reactive oxygen species （ROS） elevation and decrease the level of Cdc25C. This process can be rescued by an antioxidant, N-acetyl cysteine. In conclusion, the results demonstrate that metavanadate can inhibit cell proliferation via cell cycle arrest at G2/M phase in DU145 ceils. Metavanadate-induced ROS formation may play an important role in this process by mediating the degradation of Cdc25C.

Effects of vanadate on the activities of mice glucokinase and hexokinase

This study aimed at acquiring knowledge on the hypoglycemic mechanisms of sodium metavanadate (SMV) showed that the liver glucokinase and muscle hexokinase activities increased rapidly after oral SMV was given, and that the blood glucose level was correlated closely with the activities of the two enzymes but not with the insulin level; which indicated that SMV could improve the altered glucose phosphorylation in diabetic mice independently of stimulating insulin secretion. This was probably one of the mechanisms of hypoglycemic effects of SMV.

Preparation of narrow band gap V_2O_5/TiO_2 composite films by micro-arc oxidation

V2Os/TiO2 composite films were prepared on pure titanium substmtes via micro-arc oxidation （MAO） in electrolytes consisting of NaVO3. Their morphology and dements were characterized by scanning electron microscopy （SEM） and energy-dispersive X-ray （EDX） analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction （XRD） and X-ray photoelec- tron spectroscopy （XPS）. Ultraviolet-visible diffuse reflectance spectra （UV-Vis DRS） were also employed to evaluate the photophysical property of the films. The VEOs/TiO2 composite films show a sheet-like morphology. Not only V205 phase appears in the films when the NaVO3 concentration of the electrolyte is higher than 6,10 g/L and is loaded at the surface of anatase, but also V4＋ is incorporated into the crystal lattice of anatase. In comparison with pure TiO2 films the V2Os/TiO2 composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V2Os/TiO2 composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation.

STUDY ON SPECTROPHOTOMETRIC DETERMINATION OF CHLORPROMAZINE

The method is based on the oxidation of chlorpromazine with ammonium metavanadate in pH 2.4 solution, the absorbance of coloured compound was measured at 530 nm. Calibration graphs are linear over the concentration range 0 to approximately 250 mu g/mL. The apparent molar absorptivity was 1.28 multiplied by 10**3 L center dot mol** minus **1 center dot cm** minus **1. The proposed method was applied to the determination of chlorpromazine tablets with satisfactory results. (Author abstract) 4 Refs.

溶胶-凝胶法制备新型锂离子负极材料MnV2O6

偏钒酸锰MnV2O6具有特殊的钛铀矿结构,被认为是最有希望成为锂离子电池的负极材料之一.采用溶胶-凝胶法制备出的MnV2O6,对其结构和形貌进行表征,结果表明所制得的样品结晶度高,无杂相,颗粒粒径较均匀.