Preparation Of Metal-organic Framework-based (MOFs) Composite Materials And Their Application In Photodegradation Of Organic Pollutants

As a major pollution,water pollution poses a serious threat to human survival and sustainable development.How to repair water pollution caused by dyes,industrial waste,drugs,etc.It is a long-term research hotspot in scientific research.At present,photocatalysis has great much attention as a green energy-saving and pollution-free degradation method.Among them,the choice of photocatalyst in the degradation process is very important.Metal-Organic Frameworks?MOFs?is an inorganic-organic crystalline hybrid material.Its structure has many advantages such as high specific surface area,complex system framework and extremely large porosity.The unique advantages of MOFs materials make them widely used in aerospace materials,gas adsorption,gas storage,drug delivery and catalysis.As a secondary structural unit of MOFs,the metal-oxide cluster structure exhibits similar physical and chemical properties to semiconductors,so it has big potential in photocatalysis.In order to further expand the photocatalytic performance of MOFs,this paper designs a series of new photocatalysts using MOFs as the host material.And the structure and properties of the material were texted.At the same time,rhodamine B?RhB?and ketoprofen?KP?were used as target pollutants to test the catalytic activity of the prepared composite materials and explore their photocatalytic mechanism.The research content is as follows:1.Based on the preparation of BiOCl and MIL-53?Fe?,a composite material MIL-53?Fe?/BiOCl?MFB?was synthesized by solvothermal method.MFB was catalyzed to degrade RhB(20 mg·L^-1)under the synergistic effect of potassium persulfate?PS?.The characterization of the material and the results of photoelectrochemical testing show that the prepared composite material has a tight heterostructure and a wide range of light absorption.The material has excellent photodegradation activity of RhB under the synergistic effect of PS.The free radical capture experiment during the degradation process show that·OH,·SO₄^-and h⁺are the main free radicals involved in photocatalytic reactions.The presence of·SO₄^-greatly enhances the ability to capture photogenerated charges,thereby improving the efficiency of carrier separation.2.A chemically stable Zr-based MOFs material of UiO-66?Zr?-NH₂ was compounded with BiOCl to prepare BiOCl/UiO-66?Zr?-NH₂?BUN?photocatalytic materials with high performance.And we perform structural characterization and photoelectric performance tests on the prepared materials.The results of RhB(20mg·L^-1)show that the degradation activity of composites is significantly higher than that of single materials,which is mainly due to the efficient charge transfer of composites and the extensive absorption of visible light.The composite has a great surface area and porosity,which also provides more catalytic and adsorption sites for the degradation process.Free radical capture and electron paramagnetic resonance?ESR?tests show that h⁺and·O₂^-play an important role in the photodegradation reaction in the reaction system.The tight heterojunction interface between UiO-66?Zr?-NH₂ and BiOCl improved the carrier separation efficiency,thereby improving the photodegradation activity.3.Pt nanoparticles?Pt NPs?prepared in advance were introduced into Ti-based MOFs MIL-125?Ti?by solvothermal method.Ag nano-particles?Ag NPs?were supported on the surface of MIL-125?Ti?by photodeposition to prepare composite materials Pt/MIL-125?Ti?/Ag?PMA?.And we perform structural characterization and photoelectric performance tests on the prepared materials.The composite was applied to the photocatalytic degradation of ketoprofen?KP?(10 mg·L^-1).The experimental results show that compared with MIL-125?Ti?,Pt/MIL-125?Ti?and MIL-12?Ti?/Ag,the composite material Pt/MIL-125?Ti?/Ag has a higher activity to degrade KP.Due to the modification of the structure of the MOFs-based photocatalyst,the two metal-MOF layers of the plasmon resonance interface?SPR?and Schottky junction interface constructed in the material greatly expand the absorption range and improve the photogeneration.The separation efficiency of electrons and holes significantly improves the photoactivity of KP.