Triazine-based nitrogen-rich porous polymeric material for selective and efficient dynamic capture of low-concentration iodine vapor and methyl iodide

Radioactive iodine (I₂) and methyl iodine (CH₃I), as common and dangerous volatile fission products in nuclear waste streams, pose a serious threat to the environment and human health due to their long-term radioactivity. Here, we aim to achieve effective co-capture of I₂ and CH₃I through the synthesis of a nitrogen-rich porous organic polymer (CTP-BPA) based on triazine through the Schiff base reaction. Various characterizations have confirmed that the material has a rich mesoporous structure and nitrogen active sites. The material exhibits excellent performance under both static and dynamic conditions: it can achieve a high equilibrium capacity (4996.5 mg/g for I₂ and 621.5 mg/g for CH₃I gas), and more importantly, in dynamic penetration experiments, it has significant absorption capacity (1052.3 mg/g for I₂ and 377.8 mg/g for CH₃I) at low concentrations (3.83 ppm for I₂ and 3.39 ppm for CH₃I). Crucially, CTP-BPA can still maintain its capturing effect in simulated harsh environments, resisting strong acids (1 M HNO₃), high temperatures (up to 500°C), and high humidity (80 % relative humidity). Comprehensive experiments and DFT theoretical analysis indicate that the high-density nitrogen active sites effectively activate and fix iodine through strong charge transfer interactions, thereby achieving the chemical sequestration of harmful iodine substances. This research provides a promising strategy and advanced materials for the safe and long-term management of radioactive iodine in environmental remediation.