Amide-Modified Polyethylenimine from Meldrum’s Acid/Aldehyde/Isocyanide/Amine Multicomponent Tandem Reaction for High-Efficiency Iodine Capture

Nuclear energy is an important form of energy supply, whereas its associated nuclear pollution issue is becoming more and more serious. The effective capture of radioactive iodines (129I and 131I), which are typical nuclear fission products, is of great practical significance. In this work, an amide-modified, cross-linked polyethylenimine (PEI) derivative (MTB-PEI) containing N/O-heteroatoms was successfully synthesized by catalyst-free multicomponent tandem reaction (MCTR) using Meldrum’s acid, terephthalaldehyde, fluorene-based isocyanide (BIF), and PEI as substrates at room temperature. The chemical structure and fundamental properties of MTB-PEI were analyzed by FT-IR, XPS, scanning electron microscope, TGA characterization, etc. Based on the polyamine-type structural characteristic of MTB-PEI, its application for iodine capture was investigated followingly. Corresponding iodine adsorption performance was studied in different phases, and the results showed that the adsorption capacities were up to 6.09 g g–1 (vapor phase), 2.04 g g–1 (organic solution phase), 1.87 g g–1 (single I2 aqueous phase), and 2.74 g g–1 (I2/KI aqueous phase), respectively. Adsorption mechanism investigation revealed that diverse N/O-containing segments and aromatic rings in MTB-PEI’s structure contributed synergistically for capturing iodine.