Study On Improvement Of Optical Absorption Properties Of BiOX（X=Cl,Br） And Photodegradation Of EE2

EE2 is one of the most active estrogens in EDCs.It widely exists in a variety of aquatic environment.It is persistent and bioaccumulative in the environment and has had adverse effects on organisms and even their offspring.Photocatalytic technology can mineralize organic pollutants into small harmless molecules such as CO₂ under illumination,which is an ideal choice for the removal of EE2.The semiconductor BiOX（X=Cl,Br）have unique layered structure and excellent photoelectric properties,but their low utilization of visible light limits their application as high-efficiency photocatalysts.In this paper,we have expanded the absorption range of BiOX（X=Cl,Br）to visible light region by two methods,and the modified materials were applied to the photocatalytic degradation of EE2.In this paper,the visible light response range of BiOX（X=Cl,Br）was broadened by I^-doping,and RhB was further used as a photosensitizer to participate in the reaction,which improved the utilization of solar energy by I-BiOBr.The microstructure and physicochemical properties of the materials were characterized by XRD,SEM,TEM,XPS,FT-IR,EDS,UV-Vis DRS,PL and BET.The effects of two different modification methods on the removal of EE2 under visible light were investigated,and the mechanisms were described.The main contents are as follows:1.BiOX（X=Cl,Br）and I-BiOX were synthesized by precipitation at room temperature.The optimal molar ratio of X/I was 3:1,and the optimal stirring time was2 h.After I^-doping,it is found that the lattice spacing of both BiOBr（1 1 0）and Bi OCl（1 0 2）facets become narrower,and the absorption ranges of visible light become wider.Under visible light irradiation,the optimal I-Bi OCl and I-BiOBr could degrade 10 m L3.0 mg/L EE2 to 95.49%and 94.46%in 20 min and 40 min,respectively.The photocatalytic degradation rates were 150.67 and 15.14 times higher than those of Bi OCl and BiOBr,respectively.2.The photocatalyst I-BiOBr with weaker activity in the prepared I-BiOX was further improved and used for the photocatalytic degradation of EE2 in the presence of RhB to achieve rapid and efficient degradation and removal of EE2.When 1 mg/L RhB was added into the reaction process,the removal rate of 10 m L 3.0 mg/L EE2 by I-BiOBr was95.1%in 4 min under visible light.The photocatalytic degradation rate was 6.82 times higher than that without RhB,and the RhB in the solution was also removed at the same time.After the addition of RhB,the phase composition of I-BiOBr did not change significantly before and after the reaction,and the specific surface area increased slightly.The characteristic functional groups of RhB appeared in FT-IR characterization,indicating that RhB was firmly adsorbed on the surface of I-BiOBr mainly by physical adsorption.After the reaction,the absorption range of I-BiOBr to visible light becomes wider.In the presence of RhB,·O₂^-is the main active species in the degradation of EE2by I-BiOBr,and the concentration of·O₂^-in the system increases significantly with the presence of RhB,indicating that the photogenerated e^-excited by RhB as a photosensitizer involve in the production of·O₂^-and increase the photocatalytic property.In the presence of RhB,the degradation rate of EE2 by P25 and commercial Bi₂O₃increased by 1.85 and 3.50 times,respectively.