Radioactive iodine in nuclear waste is increasingly harmful to the human body and the environment because of its strong radioactivity, high fluidity, easy solubility in water, and long half-life. It is very important to find clean and economical materials to recover and fix radioactive iodine. In this paper, the amino-metal-organic framework was covalently modified to obtain composite materials to improve the recycling of iodine in the environment. These adsorbents are used to adsorb iodine in water, showing outstanding adsorption performance. The adsorption data are in good agreement with the Langmuir isothermal adsorption model and pseudo-second-order kinetic model, indicating that the adsorption process is mainly monolayer adsorption and chemical adsorption. The two materials showed selective adsorption capacity for iodine in the solution containing multiple competing ions. The adsorption capacity of the covalently modified composite increased from 949.52 to 2157.44 mg/g. Compared with the amino-metal-organic framework, the modified composite contains more electron-rich groups as active sites, and forms charge transfer compounds with iodine to realize chemical adsorption. Through the simulated adsorption of ultra-high-pressure micro-jet, the material has certain working ability under high pressure, which provides a theoretical basis for the future recovery and utilization of iodine under high pressure.
Keywords: Covalent organic frameworks (COFs); Iodine; Metal-organic frameworks (MOFs); Simulated adsorption; Ultra-high pressure.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.