Hydroxy functionalized triptycene based covalent organic polymers for ultra-high radioactive iodine uptake

Nuclear energy is considered as the best alternative to fossil fuel to meet the ever-increasing global electricity demand. Nuclear electricity generation is not associated with direct emission of greenhouse gases unlike thermal power plants. On the flipside, tackling nuclear waste and spent fuel is a major issue, which becomes even more challenging due to the presence of volatile radionuclides such as 131I and 129I. In unfortunate events of accidental release of fission products in the environment, 131I and 129I are considered as the most dreaded air pollutants. Therefore, development of materials for efficient and rapid uptake/storage of 129I or 131I, is a research topic of utmost importance in this context. Herein, we report unique triptycene based covalent organic polymers (T_COPs) derived from benzene-1,3,5-tricarbaldehyde derivatives possessing varying number of hydroxy groups. The microporous T_COPs feature presence of abundant imine groups and π-rich environment. Interestingly, we observed that varying the number of hydroxy groups in T_COPs alter their surface area as well as their iodine uptake capacity. T_COPs exhibited ultra-high iodine uptake up to 4860 mg/g, which is superior compared to previously reported COPs. For practical applications, the T_COPs can be reused up to five cycles with smaller loss in the uptake performance - a desirable feature expected in a superior adsorbent. Our results reflect immense potential of these triptycene based COPs for environmental remediation.