Porous pillar[6]arene-based polymers for reversible iodine capture

Iodine in nuclear waste can cause serious environment pollution and health risks, and has thus driven more development of materials for iodine capture. Herein, a novel porous pillar[6]arene-based polymer (P-P6APs) was easily prepared as a supramolecular adsorbent for iodine via a one-step crosslinking reaction between per-hydroxylated pillar[6]arene and decafluorobiphenyl. Nitrogen adsorption tests demonstrated that this material possessed a satisfactory surface area (S _BET = 366 m² g^-1) and pore diameter (3.8 nm), which was due to the macrocyclic scaffolds. Compared with commercially available activated carbon, P-P6APs exhibited superior adsorption efficiency toward volatile iodine not only in the solution phase (water and n-hexane) but also in the gas phase. This outcome was mainly ascribed to nonspecific adsorption by the pore structure of the crosslinked material coupled with multiple intermolecular binding sites of the macrocyclic scaffold. Moreover, this supramolecular absorbent was recyclable and could be reused 5 times with no obvious loss of performance.