Preparation And Photocatalytic Performance Of Transition Metal Oxides（Fe₂O₃, NiO, ZnO） Pillared Layered HMWO₆（M= Nb,Ta） For Degradation Of Rhodamine B

(1) Preparation and photocatalytic performance of iron oxide-pillared layered HMWO6(M = Nb,Ta) for degradation of rhodamine B(Rh B)Using layered niobium-tungsten acid(or tantalum-tungsten acid) as host, iron oxide as guest, iron oxide-pillared layered niobium-tungsten acid(or tantalumtungsten acid) were prepared by ion-exchange method at room temperature. A series of iron oxide-pillared layered niobium-tungsten acid(Fe2O3-HNb WO6) and tantalum-tungsten acid(Fe2O3-HTa WO6) were prepared by using different amount of Fe(Ⅲ)-pillaring agent. It was found that Fe content of the Fe2O3-pillared layered product increased with increasing dosage of Fe( Ⅲ)-pillaring agent. The photocatalytic performance of the Fe2O3-pillared layered product for degradation of Rh B was greatly improved, compared with un-pillared layered niobium-tungsten acid(or tantalum-tungsten acid). For Fe2O3-pillared layered niobium-tungsten acid, the one showed the best photocatalytic activity contained 3.6 wt% irons. And for Fe2O3-pillared layered tantalum-tungsten acid, the best one contained 5.8 wt% iron.The Fe2O3-pillared layered niobium-tungsten acid and tantalum-tungsten acid were doped with nitrogen by using urea as nitrogen source. It was found that for the Fe2O3-pillared layered product with relatively-high Fe content, nitrogen doping could improve its photocatalytic performance, and for that with low Fe content, nitrogen doping would lower its catalytic activity.(2) Preparation and photocatalytic performance of the nickel oxide-pillared layered HNb WO6 for degradation of Rh BThe Ni(Ⅱ)-complex was produced by using nickel nitrate, and ethylenediamine, which was a complexing agent. The Ni(Ⅱ)-complex cations were intercalated into the interlayers of HNb WO6 through ion-exchange way. Then nickel oxide-pillared layered niobium-tungsten was obtained by calcining the layered intermediate at a high temperature(673 K). The complex ions concentration played an important role for the intercalation. With increasing the Ni(Ⅱ)-complex concentration, the extent of the intercalation increased. Due to limitation of nickel nitrate solubility, it was difficult to finish the reaction completely. Compared with the pure layered niobium-tungsten acid, photocatalytic performance of nickel oxide-pillared layered niobium-tungsten for photodegradation of Rh B was improved obviously, and the layered product with 7.2 wt% nickel was the best one.(3)Preparation and photocatalytic performance of zinc oxide-pillared layered tantalum-tungsten acid, zinc oxide and silica copillared layered tantalum-tungsten acid for degradation of Rh BBy using ethylenediamine(En) and 3-(2-aminoethylamino) propyltrimethoxysiane(AAPTS) as the complexing agent, Zn( Ⅱ) complexes ions were obtained from the reaction between each complexing agent and zinc nitrate, respectively. Then, intercalations were carried out by mixing the Zn(Ⅱ) complexes ions and n-propylamine-pre-expanded layered tantalum-tungsten acid(C3-HTa WO6). Zinc oxide pillared layered tantalum-tungsten acid, zinc oxide and silica copillared layered tantalum-tungsten acid were obtained upon calcination. For zinc oxide-pillared tantalum-tungsten acid catalysts, the sample with 5.0 wt% of zinc showed the best catalytic performance for photocatalytic degradation of rhodamine B. For the zinc oxide and silica copillared layered tantalum-tungsten acid catalysts,the one prepared under condition of n(Zn(NO3)2):n(AAPTS) = 1:2 showed the best catalytic effect.Zinc oxide-pillared layered HTa WO6(Zn O-HTa WO6) were doped with nitrogen and the N-doped Zn O-HTa WO6 were used for photodegradation of Rh B. We found that only the photocatalytic performance of the zinc oxide-pillared layered HTa WO6 with relatively-high Zn content(for example ≥5.9 wt%) could be improved by means of nitrogen doping.