The Synthesis And Iodine Adsorption Performance Of Novel Crown Ether-based Microporous Organic Polymers

While human beings are using nuclear energy,nuclear leaks occur due to improper handling or negligence.Nuclear industrial waste from nuclear leaks contains radioactive iodine ¹²⁹I and ¹³¹I,and the half-lives of radioactive ¹²⁹I and ¹³¹I are 8.02 days and 15.7million years respectively.Long-term exposure to radioactive iodine will pose a potential threat to human health and safety.How to deal with radioactive iodine in a timely and proper manner has become a huge challenge.Among many treatment methods,adsorption method has attracted much attention because of its advantages of simple operation,high efficiency and low energy consumption.In recent years,microporous organic polymers（MOPs）show great application potential in adsorption,catalysis,optoelectronics,sensing and other fields because of their highly uniqueπ-πconjugated structure,permanent hierarchically porous structure,large specific surface area,excellent physical and chemical stability,and adjustable molecular structure.Based on the potential advantages of microporous organic polymers in the field of adsorption,a series of microporous organic polymers were synthesized by using crown ether molecules with ring structure as monomers,and their adsorption properties for iodine in gaseous and organic solvents were studied.The main research contents of this paper are as follows:（1）Two novel crown ether-based hypercrosslinked polymers,DB14C4-HCP-1 and DB14C4-HCP-2,with flexible chains,were synthesized by Friedel-Crafts reaction using dibenzo-14-crown-4,dimethoxymethane and dichloro-p-xylene as monomers,respectively.The specific surface areas are 18 m² g^-1 for DB14C4-HCP-1 and 749 m² g^-1for DB14C4-HCP-2.The adsorption performance of iodine from volatile gaseous iodine and organic solvents by two hypercrosslinked polymers was studied and investigated.The experimental results showed that DB14C4-HCP-1 had a large adsorption capacity(2.23g g^-1)for volatile gaseous iodine.But the adsorption capacity of DB14C4-HCP-1 and DB14C4-HCP-2 for iodine in organic solvent was lower.Thermodynamic,kinetic experiments and FT-IR characterization showed that the adsorption of iodine in gaseous and organic solvents by the two samples belonged to physical adsorption.（2）Two novel three-dimensional reticulated crown ether-based conjugated microporous polymers,TIDB14C4-CMP-1 and TIDB14C4-CMP-2,with rigid chains,were synthesized by Sonogashira-Hagihara cross-coupling reaction using 3,4,3’,4’-tetraiododibenzo-14-crown-4 and 1,3,5-triethynylbenzene as monomers,respectively.The specific surface areas are 186 m² g^-1 for TIDB14C4-CMP-1 and 285 m² g^-1 for TIDB14C4-CMP-2.The adsorption performance of iodine from volatile gaseous iodine and organic solvents by two conjugated microporous polymers was studied and investigated.The experimental results indicate that TIDB14C4-CMP-2 has a large adsorption value(2.03 g g^-1)for volatile gaseous iodine.Moreover,TIDB14C4-CMP-1and TIDB14C4-CMP-2 had higher adsorption capacity for iodine in cyclohexane solution.It has been revealed by thermodynamic,kinetic experiments and FT-IR that the adsorption of iodine in gaseous and organic solvents for two samples pertains to physical adsorption.（3）Two novel crown ether-based conjugated microporous polymers,TIDB14C4-CMP-3 and TIDB14C4-CMP-4,with different strut lengths and rigid chains,were synthesized by Sonogashira-Hagihara cross-coupling reaction using 3,4,3’,4’-tetraiododibenzo-14-crown-4,1,4-diethynylbenzene and 4,4’-diethynylbiphenyl as monomers.The specific surface areas are 8 m² g^-1 for TIDB14C4-CMP-1 and TIDB14C4-CMP-2.The adsorption performance of iodine from volatile gaseous iodine and organic solvents by two conjugated microporous polymers was studied and investigated.The experimental results suggested that the adsorption capacity of TIDB14C4-CMP-3 for volatile gaseous iodine is 2.18 g g^-1.Furthermore,both TIDB14C4-CMP-3 and TIDB14C4-CMP-4 showed high adsorption of iodine in cyclohexane solution.It has been validated by thermodynamic,kinetic experiments and FT-IR that two samples obey to physical adsorption for iodine capture in the gaseous state and iodine adsorption in organic solvents.