The Influence Of Titanium Oxide Morphology And Facet For U(?) Removal

The radionuclides and organic matter in radioactive wastewater pose a great potential threat to the ecological environment.It is an urgent problem to effectively treat radioactive pollution for the development of nuclear industry.Metal oxides are widely concerned in environment management based on their non-toxic property,easy preparation and low price,etc.But the limitation of metal oxides'application is that their low efficiency for pollutants removal.Fortunately,recent studies have shown that the properties of metal oxides are highly depended on their morphology,size and facet.Therefore,we mainly focus on these properties to research the relationship for U(VI)removal.By combining experiments and theoretical calculations,we investigate the interaction mechanism between titanium oxide and U(VI).Our researches provide some guidance for metal oxide synthesis.The content of this article is mainly listed below:(1)Three kinds of TiO2 with {001},{100} and {101} facets are successfully synthesized,respectively.Firstly,we study the adsorption capacity of U(?)by three TiO2,the result follows the order {001} Tio2>{100} Tio2>{101} TiO2.Density functional theory(DFT)calculations indicate that the monodentate structure is favored for U(VI)adsorption on the{001}TiO2,whereas the bidentate structures are preferred for{100}TiO2 and{101}TiO2.The U(VI)can be photoreduced to U(IV),and the U(?)removal rate follows the order {001} TiO2>{100} TiO2>{101} TiO2.The steady fluorescence emission spectra(PL),time-resolved photoluminescence spectra,I-T curve,EIS and Mott-Schottky plots suggest that the difference performance for U(?)photoreduction can be ascribed to the different photogenerated carrier separation and recombination ability of three TiO2.The results indicate that TiO2 with different exposed crystal facet has a significant influence on U(?)removal.(2)We explore a new method to synthesize three kinds of N-doped TiO2(TiO2(N))with different morphology and surface area.The morphology of three kinds of TiO2(N)are micro-flower structure with {100} and {101} facet,solid spherical structure with{101} facet,and hollow spherical structure with {100} facet,respectively,denoted as F-TiO2(N),S,S-TiO2(N)and H,S-TiO2(N).The U(?)removal rate of three samples follows the order H,S-TiO2(N)>F-TiO2(N)>S,S-TiO2(N),the organic matter degradation results are in consistent with U(?)removal.The specific surface area of three kinds of samples follows the order F-TiO2(N)<S,S-TiO2(N)<H,S-TiO2(N),from which it can be found that the crystal facets are important for pollutant removal.The characterization of PL,I-T curve and EIS show that the different photogenerated carrier separation and recombination ability of three samples results in different efficiency for pollutant removal.The results indicate that the TiO2(N)with different morphology and size has a great influence on U(?)and organic removal.