Phosphine-based covalent organic framework for highly efficient iodine capture

Abstract

The efficient capture of nuclear waste such as radionuclide iodine has received more worldwide attention because of the effects of radiation on biological health. Adsorption is considered to be an efficient, low-cost, and environmentally friendly method for iodine removal. Recently, a new kind of phosphine-based covalent organic frameworks (P-COFs) with flexible and nonplanar structure have attracted great attention because of their high specific surface area and good thermal stability. The existence of electron-rich heteroatoms (P, N) as well as the large π-conjugated network structure may be beneficial to the absorption of iodine. In this study, a biphenyl linked P-COF was synthesized for the capture of iodine. It shows a uniform microsphere structure with a diameter of about 1.2 μm, a large BET surface area up to 1056 m 2 g −1 , and a high thermal stability (up to 500 °C). This P-COF exhibits rapid and exceptional iodine uptake in both volatile iodine and iodine/cyclohexane solution with adsorption capacities of 6.19 g g −1 and 1.30 g g −1 , respectively, suggesting that P-COF may be a potential candidate for radioiodine capture from nuclear waste. • A phosphine-based covalent organic framework (P-COF) is developed for the capture of iodine. • P-COF exhibits rapid volatile iodine uptake with an adsorption capacity of 5.00 g g −1 within 2 h. • The equilibrium adsorption capacity of vapor iodine reaches as high as 6.19 g g −1 . • P-COF shows tremendous iodine adsorption with capacity of 1.30 g g −1 in cyclohexane solution.