Successful Decontamination of ⁹⁹TcO₄⁻ in Groundwater at Legacy Nuclear Sites by a Cationic Metal‐Organic Framework with Hydrophobic Pockets

Abstract

Abstract 99 Tc contamination at legacy nuclear sites is a serious and unsolved environmental issue. The selective remediation of 99 TcO 4 − in the presence of a large excess of NO 3 − and SO 4 2− from natural waste systems represents a significant scientific and technical challenge, since anions with a higher charge density are often preferentially sorbed by traditional anion‐exchange materials. We present a solution to this challenge based on a stable cationic metal‐organic framework, SCU‐102 (Ni 2 (tipm) 3 (NO 3 ) 4 ), which exhibits fast sorption kinetics, a large capacity (291 mg g −1 ), a high distribution coefficient, and, most importantly, a record‐high TcO 4 − uptake selectivity. This material can almost quantitatively remove TcO 4 − in the presence of a large excess of NO 3 − and SO 4 2− . Decontamination experiments confirm that SCU‐102 represents the optimal Tc scavenger with the highest reported clean‐up efficiency, while first‐principle simulations reveal that the origin of the selectivity is the recognition of TcO 4 − by the hydrophobic pockets of the structure.