Highly selective removal of Technetium-99 using imidazolium-based macroporous anion exchange resins

Technetium-99 ( 99 Tc), as a β-emitting radionuclide, is one of the main components of nuclear waste. The fast environmental mobility of 99 TcO 4 - makes it a great threat to the environment and human beings. Although some adsorption materials have been developed to remove 99 TcO 4 - from the nuclear wastewater, the low selectivity and poor stability under acid and radiation conditions limit their actual application. In this work, an N -methylimidazolium modified macroporous anion exchange resin (PMiMCl) was developed for the highly selective removal of 99 TcO 4 - . Batch adsorption experiments demonstrated that the PMiMCl resin exhibited high adsorption capacity (Re(VII), 677.21 mg g −1 ) in a wide pH range (3–7). The resin showed high stability after acid (5 mol L -1 HCl), alkali (5 mol L -1 NaOH) and radiation (1000 KGy 60 Co γ) treatment and the remove ability was little influenced. More importantly, in the presence of high concentration of competing anions, the removal efficiency of 99 TcO 4 - with PMiMCl resin can also reach to 97.64%, which was much higher than those treated by commercial resins (93.02% for ZGANR170 and 93.10% for IRN78), demonstrating its good selectivity. The density functional theory calculations revealed that the high selectivity was attributed to the strongest interaction of imidazole cation in PMiMCl resin with 99 TcO 4 - anion compared with NO 3 − , SO 4 2− and Cl − anions. These superior features coupled with low cost and feasible for large scale production and application make PMiMCl resin great potential for 99 Tc removal in nuclear wastewater.