Catalytic Properties Of Visible Light Responsive Bi₂₀TiO₃₂ Preparated By Solvent Thermal Method

Bi and Ti,as environmentally friendly elements,are widely used in the field of photocatalysis.Bi₂₀TiO₃₂,as one of the bismuth titanate materials with the narrowest band gap energy,has the best visible light response.The research content of this paper is as follows:1.Taking Bi?NO₃?₃·5H₂O and C₁₆H₃₆O₄Ti as raw materials,Glycol and propylene glycol are mixed solvents,Bi₂₀TiO₃₂ photocatalyst with visible light response was prepared by solvent thermal method.The best preparation conditions were determined as the reaction temperature 140?,16h reaction time,calcination temperature 300?.The volume ratio of glycol to propylene glycol is 4:1.RhB dye was treated with single phase Bi₂₀TiO₃₂,and the best chrominance removal rate was 77.87%.The samples obtained by SEM analysis showed a combination of nanowire and circular shape.2.The metastable Bi₂₀TiO₃₂ catalytic material prepared under the optimal conditions was loaded on the silica gel material to improve the photocatalytic performance,and more conducive to the recovery of catalyst.The optimum silica gel content was determined to be 30%and the optimum preparation time was 16h.SEM spectra show that the whole body is an irregular flaky group or a spherical group with small particle size.The UV-vis spectrograph showed that the visible light absorption capacity of Bi₂₀TiO₃₂ catalyst was much higher than that of the first-generation photocatalyst TiO₂.However,the catalyst loaded with silica gel slightly increased the wavelength of light absorption,and the position of the catalyst absorption sideband moved from 570nm to 630nm.3.Through single factor condition optimization experiment and orthogonal experiment,it is concluded that:The best treatment conditions for rhodanine B dye solution treated with silica gel-Bi₂₀TiO₃₂ catalyst:RhB initial concentration of 8mg/L,RhB initial pH=3,the optimal dosage of catalyst is 1g/L,under visible light irradiation,RhB chromaticity removal rate within 3h is up to 94.53%.COD removal rate reached 69.21%.The optimal conditions for the treatment of malachite green dye solution with silicon-Bi₂₀TiO₃₂ catalyst were as follows:the initial concentration of MG was10mg/L,the initial pH of MG was 1,the optimal dosage of the catalyst was 2g/L,the visible light irradiation for 3h,and the removal rate of MG chromaticity was up to96.08%.COD removal rate was 71.30%.4.The recovery experiment showed that,with the increase of recovery times,the efficiency of silica gel-Bi₂₀TiO₃₂ catalyst in the treatment of rhodemine B decreased.After three times of recovery,RhB's chromaticity removal rate was 89.57%,81.23%and 73.53%,respectively.This indicates that the stability of the loading material is not good and needs to be improved.