Preparation,vanadium Doping And Photocatalytic Performance Of Bismuthate Nanoscale Materials

Bismuthate nanoscale materials exhibit great application potential in the field of the photocatalytic treatment of organic pollutant owing to narrow band gap,large specific surface area,good chemical stability and optical performance.La bismuthate nanorods and Ca bismuthate nanoflakes have been prepared by the hydrothermal process using sodium dodecyl benzene sulfonate(SDBS)and cetyltrimethylammonium bromide(CTAB)as the surfactant,respectively.The composition,structure,morphology,size and optical performance of the obtained products were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution TEM(HRTEM)and solid UV-vis diffuse reflectance spectrum.The roles of the preparation parameters on the formation of the La bismuthate nanorods and Ca bismuthate nanoflakes were also analyzed.V doped La bismuthate nanorods and V doped Ca bismuthate nanoflakes have been prepared by the hydrothermal route using sodium vanadate as the V source.The photocatalytic performance of the bismuthate nanoscale materials for the photocatalytic degradation of methylene orange(MO)and gentian violet(GV)were researched in detail.The roles of the light irradiation time and dosage of the bismuthate nanoscale materials on the photocatalytic performance for the degradation of MO and GV were analyzed in detail.The research provides important experimental and theory basis for the photocatalytic application of the bismuthate nanoscale materials by the controlled preparation of bismuthate nanoscale materials and V doping.It is of theory and practical research significance in the effluent treatment field.La bismuthate nanorods have been prepared by the hydrothermal route using sodium bismuthate and La acetate as the source materials,SDBS as the surfactant.The obtained La bismuthate nanorods are composed of single crystalline orthorhombic La_1.08Bi_0.92O_3.03 phase.The La bismuthate nanorods have the length of longer than 10?m and diameter of 20-100 nm,respectively.SDBS concentration,hydrothermal temperature and reaction time have key roles on the formation of La bismuthate nanorods.5wt.%SDBS,180?for 24 h are the optimal preparation parameters for the preparation of the La bismuthate nanorods.Solid UV-vis diffuse reflectance spectrum shows that the band gap of the La bismuthate nanorods is 2.37e V.Photocatalytic analysis result shows that the MO degradation ratio increases obviously with increasing the light irradiation time and dosage of the La bismuthate nanorods under sunlight irradiation.The reaction rate constant for the photocatalytic degradation of MO using La bismuthate nanorods is 0.568 h^-1.MO solution with the concentration of 10 mg·L^-1 can be totally removed by the La bismuthate nanorods with the dosage of more than 10 mg in 10 m L 10 mg·L^-1MO solution.Ca bismuthate nanoflakes have been prepared via a hydrothermal route using sodium bismuthate and calcium chloride as the source materials,CTAB as the surfactant.The obtained Ca bismuthate nanoflakes possess single crystalline monoclinic Ca Bi₂O₄ phase.The size of the whole nanoflakes is about 10?m and thickness of the nanoflakes is about 40 nm.CTAB concentration,hydrothermal temperature and reaction time play key roles in the formation of the Ca bismuthate nanoflakes.5wt.%CTAB,180?for 24 h are the optimal preparation parameters for the preparation of Ca bismuthate nanoflakes.Solid UV-vis diffuse reflectance spectrum shows that the band gap of the Ca bismuthate nanoflakes is 2.21 e V.Photocatalytic analysis result shows that the GV degradation ratio increases obviously with increasing the light irradiation time and dosage of the Ca bismuthate nanoflakes under sunlight irradiation.The reaction rate constant for the photocatalytic degradation of GV using Ca bismuthate nanoflakes is 0.443 h^-1.GV solution with the concentration of 10 mg·L^-1 can be totally removed by the Ca bismuthate nanoflakes with the dosage of more than 10 mg in 10 m L 10 mg·L^-1 GV solution.Vanadium doped lanthanum bismuthate nanorods with the vanadium doping ratio of 1 wt.%,3 wt.%,5 wt.%and 10 wt.%have been prepared by the hydrothermal process using sodium vanadate as the vanadium source,sodium bismuthate and La acetate as the source materials.XRD patterns show that the vanadium in 1 wt.%vanadium doped La bismuthate nanorods exists as triclinic Bi₂₃V₄O_44.5 pahse.Vanadium in the vanadium doped La bismuthate nanorods with the V doping ratio of more than 3 wt.%exists as the triclinic Bi₂₃V₄O_44.5 and monoclinic La VO₄ phases.SEM observations show that the morphology and size of the products depend on the vanadium mass ratio.The length of the nanorods decreases to less than 1?m and irregular particales are formed with increasing the V doping ratio.Solid UV-vis diffuse reflectance spectra show that the band gap of the vanadium doped lanthanum bismuthate nanorods is narrowed to 2.25 e V with increasing the V doping ratio.Photocatalytic analysis result shows that the MO can be totally degraded by 1 wt.%and 3 wt.%V doped La bismuthate nanorods under light irradiation for 6 h.MO can be totally degraded by 5 wt.%and 10 wt.%V doped La bismuthate nanorods under light irradiation for 5 h.The reaction ratio constant for the photocatalytic degradation of MO using La bismuthate nanorods with the doping ratio of 1 wt.%,3 wt.%,5 wt.%and 10 wt.%is 0.543 h^-1,0.573 h^-1,0.653 h^-1 and 0.738 h^-1.10 wt.%vanadium doped lanthanum bismuthate nanorods have the best photocatalytic performance for the degradation of MO.Vanadium doped Ca bismuthate nanoflakes with the vanadium doping ratio of 1wt.%,3 wt.%,5 wt.%and 10 wt.%have been prepared by the hydrothermal process using sodium vanadate as the vanadium source,sodium bismuthate and Ca chloride as the source materials.XRD patterns show that the vanadium in 1 wt.%and 3 wt.%vanadium doped Ca bismuthate nanoflakes exists as triclinic Bi_3.5V_1.2O_8.25 pahse.Vanadium in the vanadium doped La bismuthate nanorods with the V doping ratio of more than 5 wt.%exists as the triclinic Bi_3.5V_1.2O_8.25 and monoclinic Ca_0.17V₂O₅phases.SEM analysis shows that the nanoscale particles are formed with increasing the V doping ratio.The size of the whole nanoflakes increases to larger than 10?m and the thickness of the nanoflakes increases to 70 nm.Solid UV-vis diffuse reflectance spectra show that the band gap of the vanadium doped Ca bismuthate nanoflakes narrowed to 1.46 e V and 1.05 e V,respectively with increasing the V doping ratio to 5 wt.%and 10 wt.%,respectively.Photocatalytic analysis result shows that the GV can be totally degraded by 5 wt.%and 10 wt.%V doped Ca bismuthate nanoflakes under light irradiation for 5 h and 4 h,respectively.The reaction ratio constant for the photocatalytic degradation of GV using Ca bismuthate nanoflakes with the doping ratio of 1 wt.%,3 wt.%,5 wt.%and 10 wt.%is 0.335 h^-1,0.351 h^-1,0.675 h^-1 and 0.839 h^-1.10 wt.%vanadium doped Ca bismuthate nanoflakes have the best photocatalytic performance for the degradation of GV.