Synthesis Of Bismuth Silicate-Based Photocatalysts And It's Application For Removal Of Environmental Endocrine Disruptors

Endocrine disrupting compounds?EDCs?not only have adverse health effects on animals or humans,but disorder the endocrine system,causing abnormal carcinogenesis.Among removal method of EDCs,photocatalytic technology as a green and efficient removal method,it stands out from many technologies.In this paper,the photocatalysts of Pt/Bi₂SiO₅ and Bi₂SiO₅/Bi₄Si₃O₁₂2 were obtained by load precious metal of Pt and construction of composite materials.The photocatalyst were characterized by XRD,SEM,TEM,XPS,UV-vis DRS,EIS and so on.The activity of the prepared photocatalyst were investigated to remove the environment endocrine disruptor?EDCs?.The details are as follows:1.The Bi₂SiO₅ nanosheets was prepared by hydrothermal method?BSO?,then,Pt/BSO was synthesized with H₂PtCl₆ as the platinum source via photoreduction method.The Pt/Bi₂SiO₅ photocatalyst was successfully synthesized and applied for removing 17?-ethynylestradiol?EE2?.In the process of photoreduction,H₂PtCl₆ was not only used as Pt resources,but also cause the BSO nanosheets assembled into flower-like structures.When the dosage of H₂PtCl₆ solution is 0.2 mL,the photoreduction time is 30min,which is the optimal material,marked as 0.2 Pt/BSO.In the optimal photocatalytic degradation condition?pH=5.8,the photocatalyst dosage is 0.5g/L?,the total degradation efficiency of EE2 reached 95.6%after only 8 min of UV-light irradiation over 0.2 Pt/BSO,and the reaction rate constant were 46.16,8.0 and 5.82 times higher than EE2 photolysis,P25 and BSO nanosheets,respectively.According to the active species capture experiment,the h⁺and·O₂^-were the main active species in photocatalytic reaction?as an electron capture center,Pt can induce the production of·O₂^-,which improves the efficiency of electron hole separation of BSO,thus improving photocatalytic activity?.0.2 Pt/BSO photocatalyst also depicted high stability and durability during three successive cycles.2.Bi₂SiO₅/Bi₄Si₃O₁₂ binary composite material was prepared by a one-step hydrothermal method.In the same hydrothermal condition,the pure Bi₂SiO₅ and Bi₄Si₃O₁₂ were prepared by change solvent,respectively.The photocatalysts were used to remove the 17?-ethynyl estradiol?EE2?,17?-estradiol?E2?and bisphenol compounds such as BPA,BPB and BPAP in water.The experimental result show that Bi₂SiO₅/Bi₄Si₃O₁₂ not only has a strong adsorption effect on EE2 and E2,but also has good photocatalytic activity.Nevertheless,Bi₂SiO₅/Bi₄Si₃O₁₂ only has photocatalytic activity for bisphenol compounds.After stirring in the dark for 30 min,the adsorption removal rate of 10mg/L EE2 and 10mg/L E2 were 60.3%and 33.8%,respectively.The total removal rate of 10mg/L EE2 reached 99.4%under UV light irradiation in 12 min and10mg/L E2 reached 98.0%under UV light irradiation in 18 min.However,when Bi₂SiO₅/Bi₄Si₃O₁₂ was applied to degrade 10mg/L BPA,10mg/L BPB and 10mg/L BPAP,the adsorption capacity are very weak and the photocatalytic removal rate were 78.5%,81.7%and88.56%under UV light irradiation in 48 min,respectively.The different adsorption performance was due to the EE2 has stronger hydrophobicity than BPA,which makes EE2 and E2 easier to dissociate from the aqueous phase and adsorbed in Bi₂SiO₅/Bi₄Si₃O₁₂.The catalytic kinetic simulation results shows that the reaction rate constant were124.96,9.69,26.41 and27.29 times higher than EE2 photolysis,Bi₂SiO₅,Bi₄Si₃O₁₂ and P25,respectively.According to the active species capture experiment,the photocatalytic degradation process was performed by h⁺,·O₂^-and·OH.Combined with relevant experimental data analysis,the E_VB is better than Bi₄Si₃O₁₂,and the E_CB of Bi₂SiO₅ is smaller than Bi₄Si₃O₁₂,which is conducive to the diffusion of photogenic electron and holes to conduction band and valence band of Bi₄Si₃O₁₂,respectively,which can reduce the recombination efficiency of electron and hole,promote the degradation of EE2.