| In this paper,the layered K4Nb6O17 was synthesized by a solid state reaction method.Then,the niobate sheets was obtained by proton-exchange,exfoliation,the exfolited nanosheets(Nb6O17-NS)were deposited into niobate nanotube(Nb6O17-NT)by an effective method of control drop acid.Composites were constructed by compositing niobate nanotube with nanoparticles,which can degrade organic pollutants in visible light.The structure,morphology and optical characteristic of samples were characterized by XRD,HRTEM,N2 adsorption desorption measurements,LRS and UV-Vis-DRS,etc.The gas chromatography(GC)analysis was used to evaluate adsorption and photodegradation activity for ethyl mercaptan(EM)under the visible light.The results indicating that the layer K4Nb6O17 was modified by ion exchange,exfoliation-restacking and deposition by the different rate to drop acid,it can be formed nanotube with difference of specific surface area and pore volumes.The optimal rate was at 0.02 mL·min-1,its specific surface area was about 196 m2·g-1,the pore volume was about 0.54 cm3·g-1 and the length was about 200～500 nm.In the range of 0.02～0.50 mL·min-1,the curl degree of the nanostroll was deepened with the rate of drop acid(R)increased,the specific surface area of the material decreased,the pore volume decreased,and the tube diameter decreased;In the range of 0.60～1.00 mL·min-1,several layers of nanosheets only can be formed half-curled nanoscroll with the rate of R increased,and more nanosheets were deposited into aggregates in the form of multilayer accumulation;When R was at 2.00 mL·min-1,there is no nanotubes can be formed,the nanosheets were deposited with multilayer,the specific surface area was gradually decreased to 53 m2·g-1 the pore volume was decreased to 0.10 cm3·g-1.The α-MnO2@Nb6O17-NT composites was prepared by modified Nb6O17-NT with α-MnO2 nanoparticles,α-MnO2@Nb6O17-NS composites were deposited to nanotube by control dropping acid with 0.02 mL·min-1.Compared with Nb6O17-NT,the specific surface area of the composites are slightly decreased(183 m2·g-1),the distribution of pore diameter are more concentration,and the pore volume decreased(0.35 cm·3·g-1).The experiment of photocatalytic degradation EM showing that theα-MnO2@Nb6O17-NT composites with better adsorption ability,stronger oxidation ability and photocatalytic degradation ability than Nb6O17-NT.This is due to the porous adsorption performance of the host nanotube,strong oxidizing with nanoparticles,and the Nb-OH bonds in support are used as the reaction active sites to link support and α-MnO2 nanoparticles,the composites own stronger interaction between the host and the guest.ZnO@Nb6O17-NT composites were also have a regular tubular structure,which has a larger specific surface area(200 m2·g-1)and a uniform pore diameter distribution,and the greater pore volume compared with Nb6O17-NT.The experiment of photocatalytic degradation EM showing that the ZnO@Nb6O17-NT composites with better adsorption ability,stronger oxidation ability and photocatalytic degradation ability.This is due to the fact that the composites have larger the surface area,the pore diameter is more uniform,the pore volume increased,and due to the interaction between the host and the guest,a strong chemical bonds are formed,may be the Zn-O-Nb bonds.The modified composites still possess the tubular structure,it shows superior adsorption and desulfuration activity under the visible light.Due to the particle size effect,the adsorption oxidation performance and the synergistic effect between the nanotubes and nanoparticles,the material has a better ability for removal ethyl mercaptan in the visible light.The construction of metal organic catalysts between metal oxide and nanotubes provides a feasible method for the synthesis of new photocatalytic materials. |
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