Photocatalytic Environmental Purification And Medical Antibacterial Properties Of Bi₂O₂CO₃ And TiO₂

Increasing environmental pollution problems are a serious threat to human life.On one hand,Nitric oxide?NO?,as one of the typical gas pollutants produced by fossil fuel combustion and automobile exhaust emissions,is extremely harmful to human organs such as the respiratory tract.On the other hand,dyes and their degradation products in dyeing wastewater discharged from various manufacturing industries are toxic and bioaccumulative,which will seriously damage the ecosystem.In addition,a large number of harmful bacteria,such as Staphylococcus aureus,are present in the polluted environment,posing a serious threat to human health.Semiconductor photocatalytic technology can use solar energy for deep pollution control under mild conditions.It has been widely studied in the fields of air purification,water pollutant degradation and medical antibacterial,and has great application prospects.In this paper,two typical semiconductor materials,bismuth carbonate?Bi₂O₂CO₃?and titanium dioxide?TiO₂?,were modified to enhance their performance in NO oxidation,dye degradation and medical antibacterial.The details are as follows:Firstly,in order to broaden the photoresponse range of Bi2O2CO3,amorphous Bi₂S₃ was deposited on the surface of Bi₂O₂CO₃ by ion exchange reaction between Bi₂O₂CO₃ and Na₂S in aqueous solution.The effects of the amount of Na₂S on the structure and properties of Bi₂S₃-Bi₂O₂CO₃ composites in photocatalytic NO oxidation were systematically investigated.The prepared Bi₂S₃-Bi₂O₂CO₃ composite nanosheets had a strong absorption in the whole visible-light region.When the content of Bi2S3 in the composite was 5%,the photocatalyst exhibited the best photoactivity,and the NO removal efficiency under visible-light irradiation was 44%higher than that of pure Bi₂O₂CO₃.Such enhancement was mainly attributed to the broadening of spectral response range and the effective separation and migration of photogenerated charge carriers on the interface of Bi₂S₃ and Bi₂O₂CO₃.Secondly,the hierarchical porous TiO₂ nanosheets were prepared by hydrothermal treatment of bulk TiO₂ in NaOH solution,and the specific surface area and pore size of the sample were controlled by adjusting the time of hydrothermal reaction.The activity of the prepared catalyst was evaluated by the decomposition of the dye reactive brilliant red X₃B and the oxidation of NO.The results show that the specific surface area of the sample increased with the prolonged alkali heating time,and the pore volume increased first and then decreased.The prepared hierarchical porous TiO₂ nanosheets exhibited excellent photocatalytic activity for X₃B degradation and NO oxidation.Among them,when the alkali heat time was 1.5 h,the X₃B removal efficiency of the hierarchical porous TiO₂ was the highest,which was8.08 times of the bulk TiO₂.When the alkali heat time was 3 h,the NO removal rate of the hierarchical porous TiO₂ reached the highest,which was 45%higher than that of the bulk TiO₂.The enhanced performance of hierarchical porous TiO₂ nanosheets was ascribed to the improved light scattering ability,enlarged surface area and pore volume,and thus promoted separation efficiency of charge carriers.Thirdly,TiO₂ semiconductor based biomaterials with magnetic separation function were synthesized by loading TiO₂ on the surface of spherical Ca₃?PO₄?₂-Fe₃O₄ composites via a sol-gel method.The cellular behavior of the prepared sample as a bone repair material and its UV-light sterilizing ability against Staphylococcus aureus were preliminarily explored.The results showed that the prepared TiO₂/Ca₃?PO₄?₂-Fe₃O₄ composites were mesoporous microspheres with a uniform size,and a complete cell membrane-encapsulated material could be successfully obtained under the action of macrophages.The TiO₂/Ca₃?PO₄?₂-Fe₃O₄composite materials exhibited a good UV antibacterial ability before and after the membrane enclose.