Preparation Of Ti-MOFs And Their Application In Photocatalytic Degradation Of RhB

Arbitrary discharge of industrial wastewater is one of the main causes of water pollution.As an industrial dye,Rhodamine B is widely used in textile,papermaking and other industries.The arbitrary discharge of these industrial sewage has caused serious harm to the environment.At present,the main treatment methods of water pollution are chemical method,physical method and biological method.Although these methods have a certain effect in the removal of dye pollution,there are no effective solutions to the problems of incomplete treatment,high cost and serious secondary pollution,which limits the practical application of these methods to a certain extent.Therefore,the development of a green and efficient dye wastewater treatment technology is of great significance for ecological and environmental protection.In many organic dyes and heavy metal water pollution treatment technologies,photocatalytic technology is a new,green water pollution treatment technology,which has great application potential in industrial dye wastewater treatment,especially for some organic pollutants with structure similar to Rhodamine B.It has the advantages of high efficiency,low price,complete and thorough,and can effectively avoid secondary pollution.At present,many photocatalysts are used in practice,mainly inorganic semiconductor materials,especially titanium dioxide（Ti O₂）.As a simple,non-toxic and harmless photocatalyst material,it has been a research hotspot in the field of photocatalysis.However,due to its narrow spectral response range and high electron hole recombination rate,it has not been widely used in wastewater treatment.The main limiting factor is that Ti O₂ only has absorption in the ultraviolet spectrum region,but has no absorption for most of the solar spectrum,so the utilization efficiency of solar spectrum is very low.MOFs,as a new material,have been widely studied in the field of photocatalysis in recent years.MOFs are a new type of porous materials composed of inorganic metal nodes and organic ligands.The connection between organic ligands and metal nodes and the topological structure order can effectively improve the separation efficiency of photogenerated electrons and holes,thus improving their photocatalytic activity.The design and preparation of titanium based metal organic frameworks is one of the effective ways to solve the narrow absorption spectrum of Ti O₂.In the titanium based metal organic frameworks,organic ligands may act as effective light absorption antennas to transfer energy to the titanium oxide clusters in the metal organic frameworks and improve their photocatalytic activity in a wide range of spectra.As a kind of macrocyclic conjugated organic ligand,porphyrin has strong absorption in the visible spectrum.Therefore,titanium-based porphyrin MOFs synthesized with porphyrin as organic ligand can improve the utilization of visible light,and regulate the structure and function through the selection of nodes and ligands.In this paper,NH₂-MIL-125（Ti）MOFs and Ti-TCPP MOFs were successfully prepared by solvothermal method with titanium as metal node and aminoterephthalic acid and 5,10,15,20-tetra-（carboxylphenyl）porphyrin as organic ligands,respectively.Their structures,morphologies and properties were characterized by spectroscopic techniques.The photocatalytic degradation performance and adsorption performance of Rhodamine B on two kinds of catalysts were studied,and the photocatalytic performance of the two materials under different wavelengths of light was explored.The experimental results show that the two photocatalysts have the ability to degrade Rhodamine B under visible light,and the degradation rate can reach more than 95%.Finally,the composition of the degradation products was analyzed by HPLC-MS.The results showed that most of the degradation products were non-toxic small molecular substances and would not cause environmental pollution.The above two materials are expected to be used in the field of photocatalysis to realize the degradation of environmental pollutant Rhodamine B by visible light.