Effective capture and reversible storage of iodine using foam-like adsorbents consisting of porous boron nitride microfibers

Abstract

Iodine has critical roles in the chemical processes within a living organism and has wide applications in chemical engineering, medicines, material sciences etc. On the other hand, the radioactive iodine could be one of the biggest hidden dangers during the nuclear accidents in the modern nuclear industry. Capture and storage of iodine is of great importance for both applications of iodine and preventing the harmful leakage of radioactive iodine. Herein, we report our efforts in utilization of monolithic boron nitride (BN) foams in capture and reversible storage of iodine in both gaseous and liquid environment. The BN foam consisting of interwoven one-dimensional (1D) porous BN microfibers inherits the merits from h-BN such as high thermal stability and chemical inertness, thus showing great resistance to harsh environments; additionally, the BN foam possesses high porosity and large specific surface areas, which make it reliable as decent adsorbents. The high internal connectivity feature, as well as the presence of a large amount of iodine adsorption sites such as π bonds and functional groups, result in the high iodine uptake capacity. Our study indicates that the adsorption amount of violate iodine by BN foams can achieve ∼212 wt%. The adsorption of iodine by BN foams in n-hexane solution follows the pseudo-second-order model best, and the adsorption isotherms are more accordant with the Freundlich model. In addition, owing to the great chemical stability of the BN foams, the desorption of iodine and recovery of the BN foam adsorbents can be achieved by either washing the foams in ethanol solution or directly heat treatment in N2 atmosphere at 800 °C for 2 h.