Selective removal of ReO₄^-/TcO₄^- by an imidazolyl-based polymer from 3 M HNO₃ solution

The effective removal of (TcO4-)-Tc-99 in the radioactive waste is very important and ReO4- was often used as the substitute of TcO4- for research. In this paper, an imidazolyl-based polymer TIB-TBPB was successfully synthesized and exhibited excellent adsorption performance for ReO4-. The results showed that the framework of TIB-TBPB is benzene-rich structure, which enhances its hydrophobicity and allows it to exhibit excellent thermal stability and acid-base stability. It could maintain the excellent recyclability even in 3 M HNO3. TIB-TBPB possessed the high capacity of 882 mg g(-1) and the superb removal depth for ReO4- and TcO4- with K-d of 2.34 x 10(6) mL g(-1) and 1.35 x 10(6) mL g(-1), respectively. Furthermore, TIB-TBPB has the advantages of excellent selectivity, recyclability and could remove 65.7 % and 86.4 % of ReO4- from 3 M HNO3 and the Hanford LAW simulated nuclear waste, respectively. DFT calculation explained the selectivity of TIB-TBPB for ReO4- over NO3- and verified the experimental results. In a word, the excellent performance suggested TIB-TBPB would be a promising material for TcO4-/ReO4- removal.