Synthesis of cationic polymer decorated with halogen for highly efficient trapping 99TcO4-/ReO4.

Abstract

The elimination of anion is of great importance from radioactive nuclear waste containing 99TcO4- by rationally designing anion-scavenging materials with high density of charge and more accessible adsorption sites. Herein, a tailor-made cationic organic polymer with donor-acceptor (D-A) structure, namely TrDCPN, was successfully synthesized by rationally modifying the benzimidazole unit for efficient trapping the perrhenate (ReO4-) as a 99Tc surrogate. Systematic control of the skeleton affect enables the material to integrate a variety of features, surmounting the long-term challenge of 99TcO4-/ReO4- remediation under extreme conditions of high acid/base and high ionic strength. Furthermore, the TrDCPN shows excellent affinity toward ReO4- in the existence of large excess of competitive anions (SO42-, NO3- and PO43-etc.) as well as promising reusability for trapping ReO4-. The excellent stability and separation were derived from the introduction of large conjugated modules, triazine core and hydrophobic. More importantly, the synthetic cationic organic polymer with D-A feature was first proved that the introduction of halogen can effectively enhance the backbone charge, and increase the adsorption capacity by synergy of ion exchange, electrostatic interaction and δ hole-anion interaction. The adsorption capacity of TrDCPN can be up to 420.3mg/g and reach equilibrium within 20min. It is noteworthy that TrDCPN successfully immobilizes ReO4- from simulated Hanford waste with a high separation efficiency of 93 %, providing a new paradigm for material design to dispose of the problem of radioactive pollutants in the environment.