Ti_(1-x)V_xO_2薄膜的制备及光电性能

用溶胶凝胶法制备了Ｔｉ１－ｘＶｘＯ２薄膜．用Ｘ射线衍射分析了Ｔｉ１－ｘＶＸＯ２的结晶性能，用Ｌａｍｂｄａ紫外－可见光光度计测量了吸收光谱，用ＺＣ３６高阻仪测量了Ｔｉ１－ｘＶｘＯ２薄膜样品的电性能，结果表明：钒含量的增加导致Ｔｉ１－ｘＶｘＯ２薄膜光学吸收限红移，在形成固溶体后薄膜的电阻率随钒含量增加而下降，在ｘ＝０．１５时，Ｖ２Ｏ５相的出现使Ｔｉ１－ｘＶｘＯ２薄膜的电阻率出现一峰值，Ｔｉ１－ｘＶｘＯ２薄膜电阻率的这种变比规律是由于Ｖ的３ｄ电子的引入和薄膜结晶性的变化．

φ-pH diagram of V-Ti-H_2O system during pressure acid leaching of converter slag containing vanadium and titanium

To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 ℃ was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH2, stable regions of V3＋, VO2＋ and VO2＋ exist in the stable region of TiO2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 ℃ of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15：1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.

Novel visible-light-responding InVO_4-Cu_2O-TiO_2 ternary nanoheterostructure: Preparation and photocatalytic characteristics

A novel visible-light-responding InVO4-Cu2O-TiO2 ternary nanoheterostructure was designed on the basis of the strategy of energy gap engineering and prepared through ordinary wet chemistry methods. The as-prepared nanoheterostructure was characterized by X-ray powder diffraction（XRD）, transmission electron microscopy（TEM）, high-resolution transmission electron microscopy（HRTEM） and diffuse reflectance ultraviolet-visible spectroscopy（UV-vis/DRS）. The TEM and HRTEM images of 10%InVO4-40%Cu2O-50%TiO2 confirm the formation of nanoheterostructures resulting from contact of the nanosized TiO2, Cu2O and InVO4 in the size of 5–20 nm in diameter. The InVO4-Cu2O-TiO2 nanoheterostructure, when compared with TiO2, Cu2O, InVO4, InVO4-TiO2 and Cu2O-TiO2, shows significant enhancement in the photocatalytic performance for the degradation of methyl orange（MO） under visible-light irradiation. With a 9 W energy-saving fluorescent lamp as the visible-light source, the MO degradation rate of 10%InVO4-40%Cu2O-50%TiO2 reaches close to 90% during 5 h, and the photocatalytic efficiency is maintained at over 90% after six cycles. This may be mainly ascribed to the matched bandgap configurations of TiO2, Cu2O and InVO4, and the formations of two p-n junctions by the p-type semiconductor Cu2O with the n-type semiconductors TiO2 and InVO4, all of which favor spatial photogenerated charge carrier separation. The X-ray photoelectron spectroscopy（XPS） characterization for the used 10%InVO4-40%Cu2O-50%TiO2 reveals that only a small shakeup satellite peak appears for Cu（II） species, implying bearable photocorrosion of Cu2O. This work could provide new insight into the design and preparation of novel visible-light-responding semiconductor composites.

Preparation of titanium mineral from vanadium titanomagnetite concentrates by hydrogen reduction and acid leaching

Titanium mineral was prepared from vanadium titanomagnetite concentrates by hydrogen reduction and acid leaching.The leaching behaviors of elements like Fe,V,Mn,Al,Mg,Ca,and Si were highly related to the reduction degree.The phase compositions of the reduced materials and the leached residues were analyzed by XRD to identify the effect of reduction degree on the leaching mechanisms.The results showed that the concentrates were reduced to iron metal and titanomagnetite at 800-1000°C for 0.5 h,and the above elements of Fe and impurities were easily leached.Deeper reduction led to the formation of ilmenite and Mg-Al spinel,which hindered leaching.Mg-bearing anosovite appeared in the further reduced materials,and the leaching rates of impurities became much lower.An upgraded titanium mineral with a normalized TiO_(2) grade of 70.3%was achieved by H_(2) reduction at 850°C for 0.5 h and acid leaching,which is a satisfactory Ti resource for the preparation of titanium oxide by sulfate process.

Vanadium recovery from Na_(2)SO_(4)-added V-Ti magnetite concentrate via grate-kiln process

Pilot experiments on Na;SO;-roasting of V-Ti magnetite(VTM) concentrate pellets were performed to activate vanadium with simulated grate-kiln machines. Combined with thermodynamic calculation, X-ray diffraction(XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy(SEM-EDS), and inductively coupled plasma-atomic emission spectrometry(ICP-AES) analyses, process parameters of pellet making were optimized, and the enhancement of vanadium oxidation and conversion was realized. The results show that, in balling stage, adding Na;SO;can promote the thermal decrepitation resistance of green pellets;in the drying stage, higher wind temperature can improve the dispersion of sodium salt in pellets;in preheating stage, using O;-rich hot gas can promote more thorough oxidation of vanadium;in roasting stage, the effect of vanadium conversion to sodium vanadate is better when the liquid amount is 15.5%-22.5%. Based on the above measures, the vanadium conversion rate achieved in the roasted pellets is 85.6%, proving the feasibility of vanadium recovery using an existing pellet production line.