Highly efficient iodine capture by polyethyleneimine-impregnated CuAl-pillared montmorillonite

Abstract

The efficient capture of radioactive iodine is significant to the safe development of nuclear energy. In this work, a novel PEI-impregnated CuAl-oxides pillared montmorillonite (PEI@CuAl-PILC) was prepared through ion exchange and immersion of polyethyleneimine to capture vapor iodine. Due to the strong affinity of amines to iodine molecules and the massive pores in the pillared montmorillonite, the synthesized PEI@CuAl-PILC exhibited a high volatile iodine uptake performance with the maximum capture capacity of 989.7 mg/g, which was much higher than montmorillonite (76.5 mg/g), CuAl-oxides pillared montmorillonite (CuAl-PILC, 189.4 mg/g) and other reported clay-based materials. These excellent properties were mainly attributed to the charge transfer from the nitrogen lone pair electrons of PEI@CuAl-PILC to the orbital of I2, which belonged to chemisorption, leading to the generation of polyiodide anions (I3-). Besides, a small proportion of iodine molecules were directly captured through the filling of pores. After five cycles, the iodine capture capacity of PEI@CuAl-PILC still remained at 906.2 mg/g. In conclusion, PEI@CuAl-PILC had a huge potential to be applied as an adsorbent for the capture of gaseous iodine in the process of spent fuel reprocessing.