Preparation Of Metal-Organic Framework/Inorganic Semiconductor Composites And Its Catalytic Degradation Of Diclofenac Sodium Under Visible Light

In the past decade,Metal-Organic Frameworks（MOFs）due to their excellent physical and chemical properties such as high specific surface area,large porosity,adjustable pore size and excellent crystallinity,thermal stability and a series of optical properties are widely used in gas storage,separation,catalysis,energy,sensing and biomedicine and have made great progress.Inorganic semiconductor material photocatalysis technology uses solar energy through photocatalysts for carbon dioxide reduction,pollutant degradation,solar cells and other fields.It has bright prospects in solving the environmental problems and energy crisis facing the world.In the research,it was found that the construction of MOFs and inorganic semiconductor materials into composite materials for photocatalytic systems can not only inherit the porosity and large specific surface area of MOFs materials and the good optical properties of inorganic semiconductor materials,It can also affect the performance of composite materials by adjusting MOF and inorganic semiconductor materials,showing the unique properties different from that of a single material,which can improve the defects of traditional semiconductor catalysis from photo-generated electron-hole pair recombination.This paper mainly designs and synthesizes visible light catalytic materials constructed with Cr-based metal-organic framework and Bi-based semiconductor materials for the degradation of diclofenac sodium（DCF）,a typical aromatic PPCPs（Pharmaceutical and Personal Care Products）pollutant.（1）A series of metal-organic framework/Bi-based semiconductor composite materials were prepared,and the materials that can respond to visible light were determined through Rh B degradation experiments,indicating that the Cr-based metal-organic framework/Bi-based semiconductor composite materials have visible light catalytic activity.（2）MIL-101（Cr）and NH₂-MIL-101（Cr）are synthesized by solvothermal method,and then MIL-101（Cr）@Bi OBr and NH₂-MIL-101（Cr）@Bi OBr compound are prepared by co-precipitation method material.It was characterized by XRD,SEM,XPS,FTIR and other characterization methods.The results showed that the two components in the prepared sample successfully compounded to form a heterojunction.Based on the UV-vis DRS test results,the band gaps of the two composite catalysts were calculated to be 2.50 and 2.35 e V,respectively.Different composition ratios will affect the catalytic performance of the catalyst.The prepared catalyst can effectively degrade DCF under visible light.Under the given conditions(DCF concentration is 10mg·L^-1,catalyst concentration is 0.6g·L^-1),the degradation rate of DCF can reach 98%within 120min.The results of free radical trapping experiments show that the main active species in the degradation process are photogenerated holes（h⁺）,as well as a small amount of hydroxyl radicals（·OH）and superoxide radicals(O^2-).（3）MIL-101（Cr）and NH₂-MIL-101（Cr）are synthesized by solvothermal method,and MIL-101（Cr）@Bi₂Mo O₆ and NH₂-MIL-101（Cr）@are prepared by secondary solvothermal method Bi₂Mo O₆ composite material.It was characterized by XRD,SEM,XPS,FTIR and other characterization methods.The results showed that the two components in the prepared sample successfully compounded to form a heterojunction.Based on the UV-vis DRS test results,the band gaps of the two composite catalysts were calculated to be 2.20 and 1.80 e V,respectively.Different composition ratios will affect the catalytic performance of the catalyst.The prepared catalyst can effectively degrade DCF under visible light.Under the given conditions(DCF concentration is 10mg·L^-1,catalyst concentration is 0.6g·L^-1),the degradation rate of DCF can reach 98%in 180 minutes.The results of free radical trapping experiments show that the main active species in the degradation process are photogenerated holes（h⁺）and a small amount of superoxide radicals(O^2-).