Synergetic Treatment Of Heavy Metals And Organic Compounds On Bi₂WO₆/Mesoporous TiO₂ Nanotube Composite Photocatalysts

Based on the phenomenon of combined pollutions of heavy metals and organic compounds widely existed in industrial waste water and natural river,the development of efficient synergistic technology for combined pollutions treatment plays a significant role for solving the present environmental problems.Semiconductor photocatalytic technology is a potential environment remediation method for the treatment of environmental pollutions.The architecture of photocatalysts is very important for material's physical properties.We designed mesoporous TiO₂ nanotubes to fundamentally modify the photocatalytic properties of TiO₂ nanoparticles.Meanwhile,the narrow band semiconductor Bi₂WO₆ was used to combine with mesoporous TiO₂ nanotubes,which could be achieved in visible light to study the treatment performance of heavy metals and organic compounds combined pollutions.Heavy metals and organic compounds could trap photo-generated electronics and holes,resulting in the separation of holes-electronic pairs,which could achieve the application of semiconductor technology for efficient synergistic treatment of heavy metals and organic compounds combined pollutions.Mesoporous TiO₂ nanotube photocatalyst was prepared by double template technology which achieved by the hydrolytic polymerization self-assembly process of organic titanium source in the solution containing hard template and organic template.The structure of samples was characterized by XRD,SEM,TEM,XPS and N₂ adsorption/desorption.The photocatalytic activity was estimated for the degradation of rhodamine B?RhB?wastewater.The results showed that the mesoporous TiO₂ nanotubes were anatase TiO₂ and the tube diameter was about 100 nm.Meanwhile,mesoporous TiO₂ nanotubes possessed a high specific surface area?219.56 m2/g?and favorable distribution of mesoporous structure.The photocatalytic performance was enhanced 9.8 times compared with TiO₂ nanoparticles,which was ascribed to the improvement of adsorption mass transfer performance and utilization rate of light with the presence of multiple channel structure of nanotubes.Bi₂WO₆-TiO₂ composite catalyst was prepared by sol-gel and solvothermal process.The structure of samples was characterized by XRD,UV-vis,SEM,EDS and photocurrent analysis.The photocatalytic activity was estimated for the degradation of Cu???-EDTA and Cu???-DBP combined pollutions.Bi₂WO₆ was combined with mesoporous TiO₂ nanotubes to design the best photocatalyst for the treatment of combined pollutions.Compared with single Cu???and EDTA,Bi₂WO₆-TiO₂ composite catalyst exhibited better treatment efficiency for Cu???-EDTA combined pollution.The optimal Bi₂WO₆ content and pH value are 5%and 4,respectively.Bi₂WO₆-TiO₂ deposited by Cu and CuO performed higher photodegradation efficiency for organic pollutions.Bi₂WO₆-TiO₂ composite catalyst exhibited same better treatment efficiency for Cu???-DBP.The deposition of heavy metal appeared optimal content.Bi₂WO₆/mesoporous TiO₂ nanotube composite photocatalyst exhibited best photocatalytic activity than other photocatalysts,which presented a new method and though for efficient synergistic treatment of combined pollutions.