Synthesis and characterization of non-porous amorphous polymers for enhanced iodine adsorption

With the increasing demand for sustainable energy sources, the management of radioactive iodine, a byproduct of nuclear energy, has become critical for environmental safety and human health. This study presents the design and synthesis of non-porous amorphous polymers, specifically PEI-PD, derived from polyethylenimine (PEI) and pyromellitic dianhydride (PD), for the adsorption of iodine from aqueous and gaseous environments. The adsorbent exhibits high efficiency in capturing iodine, with a remarkable adsorption capacity of 4.43 g g-1 for volatile iodine and 1.43 g g-1 for liquid iodine. The adsorption process is governed by a pseudo-second-order kinetic model and follows the Langmuir isotherm, indicating a chemisorption mechanism driven by electrostatic attraction. The mechanism of iodine adsorption by the adsorbent was investigated using infrared spectroscopy and independent gradient modeling (IGMH), which helped to clarify types of weak interaction between the adsorbent and iodine and the adsorption sites. The study highlights the potential of PEI-PD as an effective material for the removal of radioactive iodine, contributing to the safe and sustainable management of nuclear waste. Non-porous amorphous polymers demonstrate exceptional iodine adsorption capacities of 4.43 g g-1 for volatile iodine and 1.43 g g-1 for liquid iodine. Insights into the adsorption mechanism were gained through FT-IR analysis and independent gradient model based on Hirshfeld partition (IGMH), elucidating the adsorption sites and weak interactions with iodine. (Image credit: Chang Sun.)