Preparation,Characterization And Photocatalytic Properties Of Bismuth Vanadate And Its Composites

Dye wastewater has been widely concerned on account of its large discharge,complex composition,high organic content,strong toxicity and so on.Photocatalytic technology can use light as energy to treat dye wastewater at room temperature.Bi based materials have significant absorption capacity in the vis-light region,strong catalytic activity and no selectivity for dye degradation.It is considered as a green technology with significant application prospects in the treatment of dye wastewater.In this thesis,BiVO₄（BVO）,Bi₂₄Fe₂O₃₉/BiVO₄（FV）and Bi₂₄Fe₂O₃₉/BiVO₄/Ag₃PO₄（FVAP）photocatalytic materials were prepared,and the material structure,morphological characteristics,element composition,functional groups,absorption spectra and magnetic properties were characterized.The photocatalytic performance was evaluated with aniline and RhB as substrates.The effects of various reaction conditions on the photocatalytic performance were investigated,and the photocatalytic mechanism was discussed.The main conclusions were as follows:1.BVO nano-photocatalyst was prepared by hydrothermal method,and the effect of different conditions on the degradation of aniline cooperate with persulfate was studied.The two crystal forms of BVO cooperate with persulfate degraded aniline.Under the conditions of 30℃,1.0g/L persulfate,the degradation rate of 10 mg/L aniline were 54.4%and 84.4%by 1.00 g/L BVO（s-t）and BVO（s-m）after 2h vis-light treatment.Trapping experiments showed that·OH and h⁺were essential active free radicals in the process of degrade aniline by BVO（s-m）cooperate with persulfate,while SO₄^·-and·O₂^-played an auxiliary role.2.FV magnetic nano-photocatalyst was prepared by hydrothermal method and high temperature calcination method.The effect of different conditions on the degradation of aniline cooperate with persulfate was studied.Under the conditions of35℃,2.00 g/L FV,1.0g/L persulfate,the degradation rate of 10 mg/L aniline was 97.4%after 2h vis-light treatment.The TOC removal rate was 59.8%.Trapping experiments showed that h⁺and SO₄^·-were essential active free radicals in photocatalytic reaction,while·OH and·O₂^-played an auxiliary role.3.FVAP magnetic nano-photocatalyst was prepared by hydrothermal method and ion exchange method,and the effect of different conditions on the degradation of RhB was studied.Under the conditions of 35℃,pH=6,1.00 g/L FVAP,the degradation rate of 10 mg/L RhB was 97.5%after 2h vis-light treatment.The TOC removal rate was43.4%.After 5 runs of FVAP,the degradation rate of RhB still reached 61.7%meant good stability of FVAP.Trapping experiments showed that·OH and h⁺were the main free radicals in the photocatalytic reaction process,while·O₂^-played an auxiliary role.In summary,bismuth vanadate and its composites prepared in this paper show excellent photocatalytic performance,which can be used for vis-light photocatalytic degradation of dye wastewater;FV and FVAP can be recycled by magnet,which avoids secondary pollution.