Hyperbranched Polyethylenimine-Segmented Silica Aerogel Attains Record-High Dynamic Capture of Radioactive Iodine

The efficient dynamic capture of radioiodine from nuclear off-gas is of great importance for nuclear safety and environmental protection. However, the limited dynamic iodine capture capacity, primarily due to insufficient mass transfer and the sluggish adsorption kinetics, remains a critical challenge for existing iodine adsorbents. Herein, we present a facile strategy to construct hyperbranched polyethylenimine-segmented silica aerogels (HPEI-SAs) for the efficient capture of volatile iodine. HPEI-SA is synthesized via siloxane hydrolysis and epoxy–amine curing between 3-glycidoxypropyltrimethoxysilane and hyperbranched polyethylenimine, yielding a macroporous silica framework (pore size >30 μm) with a low bulk density of 0.20 g/cm3. The incorporated hyperbranched polyethylenimine segments provide a high density of amine binding sites, enabling exceptional uptake capacities of 6.0 g/g for gaseous iodine and 4.7 g/g for dissolved iodine. Notably, the synergy of abundant active sites and the macroporous architecture affords a record-high dynamic iodine capture capacity of 3.7 g/g. In addition, HPEI-SA combines low production cost (∼$83.5/kg), excellent processability, and high thermal stability, underscoring its strong potential for deployment in practical iodine filtration systems. This preparation strategy for constructing a predominantly macroporous structure with a high density of active sites provides valuable insights into the design of advanced materials for volatile pollutant removal.