Preparation Of Organic Framework Materials And Their Adsorption Of Iodine

Radioactive iodine is one of the most toxic radionuclides in radioactive waste due to its high radiation yield,volatility,environmental mobility and significant radiological hazard.Therefore,the treatment of radioactive iodine wastewater must include volume reduction and radioactive iodine capture to ensure safe discharge into the environment.The adsorption method for enrichment and recovery of iodine has the advantages of efficient,simple operation,and environmental sustainability.Research on low-cost and high-efficiency adsorption materials to achieve effective treatment of radioactive iodine.In this paper,metal organic frameworks,amino metal organic frameworks and covalently modified amino metal organic frameworks were synthesized.At the same time,the use of field emission scanning electron microscopy and X-ray energy dispersive analysis（SEM-EDS）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）and other analysis tests The methods were used to analyze the structure and surface characteristics of the materials,and it is applied to static adsorption of iodine to study the adsorption mechanism of iodine.1.The metal-organic framework（MOF）was successfully prepared by solvothermalmethod,and the adsorption mechanism of iodine on MOF were investigated.The adsorption results show that the adsorption process is mainly chemical adsorption,accompanied by partial diffusion.The adsorption of iodine by MOF is mainly multimolecular layer adsorption,accompanied by monad layer adsorption to a certain extent.The maximum adsorption capacity of iodine on MOF is 301.53 mg/g.The adsorption process is a spontaneous reaction,and proper temperature increase is favorable to the adsorption process.At the same time,ir spectra showed that the characteristic absorption peak of benzene ring had red shift after iodine adsorption,indicating that charge transfer complex was formed between iodine and benzene ring.2.Amino metal-organic skeleton(NH_2-MOF)was obtained by aminationmodification for metal-organic skeleton（MOF）,and the adsorption performance and mechanism of iodine by NH₂-MOF were explored.Experimental results show that,.The adsorption of iodine by NH₂-MOF is mainly chemical adsorption,which also indicates that iodine and NH₂-MOF are firmly bound.The adsorption of iodine by NH₂-MOF is mainly monolayer adsorption.The maximum adsorption capacity of iodine on NH₂-MOF is 949.52 mg/g.The adsorption thermodynamics shows that the adsorption process is a spontaneous reaction,and proper temperature increase is favorable to the adsorption process.3.Amino metal-organic framework（NH₂-MOF）was covalently modified to obtain an amino metal-organic framework（COF@NH₂-MOF）containing covalent bonds,and the adsorption performance and mechanism of iodine by NH₂-MOF were investigated.The experimental results show that the adsorption process is mainly chemical adsorption,and the iodine adsorption capacity of COF@NH₂-MOF is 2157.44 mg/g.The results show that the modification of covalent bonds on the amino metal organic framework can indeed increase the amount of iodine adsorption,so as to achieve the enrichment and recovery of iodine in the environment.Adsorption thermodynamics shows that increasing temperature is beneficial to the adsorption process,COF@NH₂-MOF has a selectivity for iodine,and has the ability to work under high pressure environment.