Cationic Covalent Organic Nanosheets for Rapid and Selective Capture of Perrhenate: An Analogue of Radioactive Pertechnetate from Aqueous Solution
journal contribution
posted on 2019-04-01, 00:00 authored by Hong-Ju Da, Cheng-Xiong Yang, Xiu-Ping YanCapture
of radioactive TcO4– from
nuclear wastes is extremely desirable for waste disposal and environmental
restoration. Here, we report the synthesis of hydrolytically stable
cationic covalent organic nanosheets (iCON) for efficient uptake of
ReO4–, a nonradioactive surrogate of
TcO4–. The iCON combines cationic guanidine-based
knots with hydroxyl anchored neutral edge units and chloride ions
loosely bonded in the pores, rendering extremely fast exchange kinetics
toward ReO4– with high uptake capacity
of 437 mg g–1 and prominent distribution coefficient
of 5.0 × 105. The removal efficiency remains stable
over a pH range of 3–12 and allows selective capture of ReO4– in the presence of excessive competing
anions such as NO3–, CO32–, PO43– and SO42– with good removal efficiency for ReO4– in a simulated Hanford LAW Melter Recycle Stream.
Anion exchange between the ReO4– in solution
and the chloride ion in iCON plays dominant role in the adsorption
of ReO4–. The iCON shows promise for
effective removal of radioactive 99Tc from nuclear waste.
