Fabrication of amidoxime grafted polyacrylonitrile for iodine vapor capture from off-gas

Abstract

The exploration of effective gaseous iodine adsorbents is an interesting and challenging task in the field of radwaste disposal. In this study, amidoxime groups (AO) were successfully grafted onto polyacrylonitrile to obtain amidoxime grafted polyacrylonitrile (PAN-AO) for capturing gaseous iodine. The results of the combined characterization analysis have confirmed that the introduction of AO greatly improved its thermostability, porosity and available functional groups of PAN. The impacts of reaction time, iodine concentration and reaction heat on the uptake capacity for gaseous iodine were systematically studied. The PAN-AO exhibited higher iodine capture capacity (1534.4 mg/g) than PAN (72.1 mg/g) at 80 °C and 600 min, which was ascribed to the chemical reaction between electron-rich AO groups and electron-deficient iodine molecules. The studies of kinetic fitting and activation energy (Ea = 44.11 kJ/mol) further confirmed that chemical adsorption was the major fashion during the whole uptake process of PAN-AO for iodine. Besides, PAN-AO still had an iodine uptake capacity of 704.4 mg/g after five recycling, manifesting the remarkable cycle performance of PAN-AO. In brief, this study offered a new reference for radioactive iodine uptake and the synthesized PAN-AO was able to serve as an efficient iodine capture material.