Effective Iodine Adsorption and Storage of Volatile Iodine by Nitrogen-Rich Porous Organic Polymers from Flexible Building Blocks

The capture of radioactive iodine species in nuclear fuel reprocessing and nuclear emergencies is of utmost significance for ensuring nuclear safety, conserving the natural environment, and maintaining the well-being of the public. Previously mentioned materials like zeolites and activated carbons for iodine capture have proven to be less effective under practical changing conditions. As a result, there is a compelling demand for developing adsorbents synthesized by simple approaches that can adsorb iodine from diverse sources with a strong adsorption capacity. In this context, we put forth a design to synthesize the nitrogen-rich porous organic polymers (NR_POP-C2 and NR_POP-C3) using a flexible trialdehyde containing a triazine core structure (TTT) and 4,4′-oxidianiline (OD) and naphthalene-1,5-diamine (ND) as monomers, respectively. The covalent linkages between the monomers were achieved via a Schiff base polycondensation reaction. The ample electron-rich aromatic rings and nitrogen centers in the polymeric network enable its efficient interaction with iodine. Certainly, NR_POP-C2 and NR_POP-C3 showed significant capture of iodine from different sources in various environments and temperature conditions for instance, at elevated temperature (75 °C: 7.16 and 6.36 g/g), at room temperature (25 °C: 2.71 and 2.25 g/g) and in aqueous medium (4680.6 and 4605.7 mg/g) at room temperature, respectively. The thermally stable NR_POP-C2 and NR_POP-C3 maintained their capture performance while being recycled. Due to the excellent iodine adsorption capacity and long-term retention capability, NR_POP-C2 and NR_POP-C3 stand out as leading materials for the steady capture and storage of iodine.