Preparation Of Porous Materials And Their Iodine Adsorption Properties

As we all know,nuclear energy will produce radioactive pollutants,which will significantly increase the risk of environmental pollution.Therefore,nuclear waste needs to be carefully managed and disposed.In the radioactive nuclear waste,¹²⁹I and¹³¹I,as two isotopes of iodine,are important and dangerous,so they need to be treated more carefully.At the same time,iodine is also a scarce resource.Due to the large number of downstream products produced with iodine and iodine containing compounds,many countries in the world have a large demand gap for iodine.Some researches claim that the content of iodine in salt-lake brine is much higher than that in seawater,which has great mining value.However,the extraction of iodine from salt-lake brine is rarely reported.In addition,due to the existence of various forms of iodine in water,it is difficult to determine the accurate content of iodine in water.Moreover,the adsorbent of iodine is generally highly polar and has poor stability in water.At present,most of the reported studies are about the adsorption of iodine from organic solvents,or the adsorption of iodine vapor by adsorption materials under high temperature and high pressure.There is no correlation between the direct adsorption of iodine from water environment Reports.In turn,it is particularly important to develop a method that can accurately determine the concentration of iodine in water.It is of practical significance to prepare materials that can effectively absorb iodine from the aqueous solution and to protect the environment and develop resources.In this paper,a method for the determination of the concentration of iodide by cyclohexane extraction is proposed.This method fundamentally solves the problem of separation of I₂,I^-and I₃^-.Cyclohexane iodine solution has good color development,strong and single absorption peak,high correlation of experimental data（R²=99.9%）.It is a better method for determination of iodide in aqueous solution.In addition,two kinds of zeolites,ZIF-8 and ZIF-67,were prepared by hydrothermal method.The morphology and chemical properties of the adsorbents were characterized by XRD,TGA,SEM-EDS,TEM and XPS.The good chemical and thermal stability and large specific surface area of the two materials were verified.The results show that in one hour,the two adsorbents can reach the adsorption equilibrium of iodine,and the adsorption behavior accords with the pseudo second-order kinetic model.The adsorption process of the two materials for iodine is linear,and the adsorption capacity for iodine can be as high as 2000.00 mg g^-1.Two kinds of metal organic framework materials PCN-223 and PCN-223-HPP（PCN-223-HPP for ultra-high-pressure treatment）with zirconium as the center ion and porphyrin as the ligand were prepared by solvothermal method,which can effectively adsorb iodine in water.PCN-223 and PCN-223-HPP have good chemical stability,thermal stability and wet stability,and can be adsorbed under high pressure of 300 MPa.The specific surface area of PCN-223-HPP is 200 cm² g^-1 higher than that of PCN-223,so the adsorption capacity of PCN-223-HPP is higher than that of PCN-223.The adsorption capacity of PCN-223 and PCN-223-HPP for iodine is as high as 1300.00 mg g^-1,and they have good renewable capacity.In addition,the adsorption effect of the material under ultra-high pressure is no different from that under normal pressure,indicating that the material has excellent stability and the ability to work under high pressure in the deep sea.