Efficient enrichment of iodine by supported ionic liquid with three effective adsorption sites: Heteroatoms, fused aromatic rings and ionic bond

Abstract

With the continuous development of nuclear energy, radioactive iodine in nuclear waste would be hazardous to human health and environment. Therefore, it is of great significance to develop an efficient adsorbent for iodine capture. In this study, a novel ionic liquid ([N4444]4PTC) was prepared which combines three effective adsorption sites of heteroatom, fused aromatic ring and ionic bond for iodine capture. To make full use of the iodine capture capacity of [N4444]4PTC, [N4444]4PTC@MF composite was fabricated by using MF as a carrier which is cheap and readily available. The hydrogen bond between MF and PTC4– increases the surface charge density of MF, and endows [N4444]4PTC with high porosity. Thus, the iodine adsorption capacity (5.81 g g−1) and adsorption rate of [N4444]4PTC@MF was significantly improved. This synergistic effect-based iodine capture system was demonstrated to convert iodine molecules into polyiodide anions via charge-transfer (CT) mechanism at electron-rich sites. The formed anionic specie was effectively stabilized by the abundant quaternary ammonium cations in the system, making it easier to take place the adsorption process and increase the stability of the captured iodine. The adsorption–desorption test showed that the composite material exhibits excellent recycling performance and was suitable for multiple use in practical applications.