Research On Crystalline Materials Constructed By Rigid Ligands And Dye Degradation Properties

As an indispensable organic compound,dyes play a vital role in daily life.They are widely used in food processing,clothing,medicine,cosmetics,military weapons,agricultural tools,and so on.With the continuous development of modern industry,more and more commercial dyes are discharged into lakes in different ways,which seriously causes water pollution.Since most of the dyes are composed of organic aromatic hydrocarbon polymers,they are difficult to degrade under natural conditions,and even have a strong corrosive effect on the human gastrointestinal tract,eyes and skin,seriously threatening people's life and health.Therefore,finding a fast,simple and effective method to degrade dyes is currently the most important primary task.The crystalline materials constructed by the rational design of rigid ligands can effectively solve the above problems.In order to give full play to the advantages of metal-organic framework compounds as catalysts,This work uses 2,6 naphthalenedic acid(NDC),terephthalic acid(BDC),The rigid ligands of 4,5-imidazole dicarboxylic acid(IMH),tetrafluoro terephthalic acid(tf BDC)and phenanthroline(Phen)as a variety of rigid ligands and transition metal cobalt and rare earth cerium as metal nodes.Six novel crystalline structures were successfully designed and synthesized by solvothermal method.The morphology,structure,stability and degradation properties of crystalline materials were characterized by X-ray single crystal diffraction structure analysis,powder X-ray diffraction,infrared spectroscopy,thermogravimetric analysis and ultraviolet absorption,respectively.The experimental results show that,the crystalline materials composed of transition metal cobalt,the rigid ligands of tetrafluorophthalic acid and phenanthroline can degrade the dye RB efficiently,rapidly and stably in the presence of PMS,the degradation efficiency can reach 99.98%.Through a large number of experiments,CoMOFs can be used as a catalyst to activate PMS and generate a large number of strongly oxidized sulfate radicals and a small amount of hydroxyl radicals.These free radicals have strong degradability and selectivity to target pollutants,which are used to degrade pollutants in water.Compared with Co-based catalysts,the Ce-MOFs catalysts are far less effective in degradation than transition metal Co-MOFs.For this reason,we also studied the influence of different catalyst dosage,PMS concentration,dye concentration,temperature,PH value UV and cycle stability on dye degradation.Among them,the amount of catalyst,dye concentration and temperature have better effect on dye degradation.This technology has important significance and far-reaching influence on purifying water pollution in the future.