Space and structure activation of collagen fiber for high efficient capture iodine in off-gas

Abstract

High efficiency capture of radioactive iodine-129 (129I) is of great significance in spent fuel treatment. In this study, we report a new method of space and structure activation for collagen fiber (CF) using strong alkali NaOH under ultrasonic-assisted to obtain activated collagen fiber (ACF) with active spatial structure and functional group. The as-prepared material was used for the capture of volatile iodine. The results show that the structure and morphology of ACF were characterized, indicating that the interchain hydrogen bonds were destroyed and the three-strand helix structure of CF was partially opened, resulting in more OH, CONH2 and NH2 groups on ACF surface were released. The iodine vapor capture capacity of ACF reached 1068.6 mg/g, which is higher than that of CF (428.3 mg/g) and most inorganic adsorbents. Furthermore, in iodine cyclohexane solution, the adsorption process accorded with pseudo first order kinetic and Langmuir isothermal model. With hydrogen bonds analysis and the experimental analysis of functional group shielding before and after adsorption, the mechanism is mainly the electron transfer between the OH, CONH2 and NH2 groups on ACF surface and iodine to form I3− coordination complex, indicating that CF exposed more beneficial iodine capture groups after alkali activation. Therefore, ACF is an efficient adsorption material for capturing radioactive iodine in spent fuel treatment off-gas.