Research And Experimental On Adsorption Of I₂ By N/S Doped Hyper-crosslinked Polymers Based On Polyvinyl Alcohol

Porous organic frameworks(POFs)are a new sort of organic porous materials,including covalent organic frameworks(COFs),covalent triazine-based frameworks(CTFs),conjugated microporous polymers(CMPs),hyper-crosslinked polymers(HCPs),porous aromatic frameworks(PAFs).Compared with traditional inorganic porous materials,like zeolites,activated carbons,POFs are often featured with high surface area,low density,and easily functionalized.Up to now,novel POFs are being developed and applied in catalysis,gas separation and storage,water treatment fields.Recently,nuclear industry including nuclear power,nuclear technology has developed rapidly,public pay more attention to the issues about radioactive wastes storage,radioactive leakage disposal.This work aims at the adsorption of radioactive I2 from environment,two N/S doped hyper-crosslinked polymers:TCDI-PVA,CDI-PVA are designed and prepared based on previous literatures.To confirm its constructions and I2 adsorption capacities,scanning electron microscope,Fourier transform infrared spectroscopy,13C solid-state NMR CP/MAS,powder X-ray diffraction,elemental analysis,thermogravimetric analysis,12 vapor adsorption experiments,adsorption kinetic/isotherm studies in I2 solutions were used and implemented.By different characterization methods,TCDI-PVA,CDI-PVA are demonstrated to be HCPs,which are formed through the substituted reactions of N,N’-thiocarbonylimidazole(TCDI),N,N’-carbonylimidazole(CDI).Besides,TCDI-PVA are characterized with 3D polymer network frameworks with vast pore structures.By I2 vapor adsorption tests,the maximum I2 adsorption capacities of TCDI-PVA,CDI-PVA are 5.9 g/g,3.5 g/g,which are outstanding among I2 adsorption materials reported so far.The good results of adsorption kinetic/isotherm experiments in water and cyclohexane suggests that TCDI-PVA is a novel I2 adsorption material with wide range of application and good performance.In adsorption mechanistic study,doped N/S are proved to be affinity sites to interacted with I2,and 3D polymer network frameworks formed by cross-linking reactions in solvent provided abundant free room to accommodate I2.