Constructing cationic covalent organic frameworks by a post-function process for an exceptional iodine capture via electrostatic interactions

Abstract

With the continuous development of nuclear energy, radioactive iodine in nuclear waste is becoming increasingly harmful to the environment and human health. Herein, we synthesized two cationic covalent organic frameworks (C-TP-PDA-COFs and C-TP-BPDA-COFs) via a post-function process for an exceptional iodine capture. Compared to that of neutral COFs, the iodine uptake capacities of cationic COFs were improved 1.3 times due to electrostatic interactions between COF networks and iodine molecules. Interestingly, C-TP-BPDA-COF possessed high-density ionic units to realize a high iodine uptake value of 6.11 g g⁻¹, which is higher than most neutral COFs and ionic porous adsorbents. This study demonstrates an effective way to construct cationic COF materials and further employ them as scaffolds for iodine capture.