Efficient and Selective Uptake of TcO4– by a Cationic Metal–Organic Framework Material with Open Ag+ Sites

• DOI: 10.1021/acs.est.7b00339
• Publication Date: 2017-02-17T13:09:52Z
• Authors: Daopeng Sheng; Lin Zhu; Chao Xu; Chengliang Xiao; Yanlong Wang; Yaxing Wang; Lanhua Chen; Juan Diwu; Jing Chen; Zhifang Chai; Thomas E. Albrech...; Shuao Wang
• Keywords: Cationic polymerization; Nuclear fission product

99Tc is one of the most problematic radioisotopes in used nuclear fuel owing to its combined features high fission yield, long half-life, and environmental mobility. There are only a handful functional materials that can remove TcO4- anion from aqueous solution identifying for new, stable with anion-exchange capacities, fast kinetics, good selectivity remains challenge. We report here an 8-fold interpenetrated three-dimensional cationic metal-organic framework material, SCU-100, which assembled tetradentate neutral nitrogen-donor ligand two-coordinate Ag+ cations as potential open metal sites. The structure also contains series 1D channels filled unbound nitrate anions. SCU-100 maintains crystallinity over wide pH range 1 13 exhibits excellent β γ radiation-resistance. Initial exchange studies show able both quantitatively rapidly water within 30 min. capacity surrogate ReO4- reaches up 541 mg/g distribution coefficient Kd 1.9 × 105 mL/g, significantly higher than all previously tested inorganic sorbent materials. More importantly, selectively capture presence large excess competitive anions (NO3-, SO42-, CO32-, PO43-) much 87% Hanford low-level waste melter off-gas scrubber simulant stream 2 h. sorption mechanism well elucidated by single crystal X-ray diffraction, showing sorbed coordinate sites forming Ag-O-Re bonds hydrogen bonds. This further leads single-crystal-to-single-crystal transformation disordered 4-fold fully ordered work represents practical case removal MOF material demonstrates promise using this type scavenger treating anionic radioactive contaminants during partitioning remediation processes.