Synthesis of imidazolium-based cationic organic polymer for highly efficient and selective removal of ReO4−/TcO4−

Rational design of anion-scavenging materials with high selectivity and stability under high acid/base extreme conditions for removing 99TcO4− is still a significant challenge. Herein, we put forward an anion exchange strategy that utilized an imidazolium-based cationic organic polymer (named ImCOP) for efficient capture of perrhenate (ReO4−), a surrogate for TcO4− with nonradioactive. ImCOP was synthesized via the quaternization reaction using tris (4-(1H-imidazol-1-yl) phenyl) amine, a tripodal flexible ligand, and 1,4-bis (bromomethyl) benzene to forming a semi-rigid structure. ImCOP exhibited high chemical stability even under 3 M HNO3 and 3 M NaOH, which was superior to those of most materials. Attributed to the charged imidazolium moieties and tertiary amine groups that produced rich adsorption sites, ImCOP can produce electrostatic interactions with ReO4−, thereby leading to a record uptake capability (1162 mg g−1) of ReO4−. Furthermore, ImCOP exhibited high selectivity for removing ReO4− in the presence of large excess of competitive anions, which was attributed to the hydrophobic surface of ImCOP. These excellent features endowed ImCOP successfully separated ReO4− from simulated Hanford waste with a high adsorption removal of 93.4%. The excellent performance suggested ImCOP would be a promising material for TcO4−/ReO4− removal, which provided a feasible pathway for designing a high-efficiency and durable material for nuclear-related environmental remediation.