Construction of a Porous Zwitterionic Polyimidazole Resin for the Elimination of Technetium in Acidic Environments

Abstract

Due to the complex type of coexisting ions, remarkable acidity, and high radioactivity, efficient and sustainable methods for the removal of pertechnetate (⁹⁹TcO₄^–) from acidic nuclear waste streams have attracted much attention. Herein, a porous highly polymeric zwitterionic resin (PDVBVIM1.5SO₃) was synthesized by installing sulfobetaine zwitterionic units in the polymeric imidazole resin to achieve the purpose of balancing the hydrophilicity and hydrophobicity of the resin structure and improving the reaction kinetics and ion selectivity of the resin at the same time for perrhenate (ReO₄^–)/⁹⁹TcO₄^– removal from acidic solutions. The results demonstrate that PDVBVIM1.5SO₃ exhibits fast adsorption kinetics, superior adsorption capacity, and excellent selectivity in the presence of a variety of 1000-fold competing anions. The rapid elimination of ReO₄^– can be achieved even in 1 mol L^–1 HNO₃. Importantly, when subject to acid soaking, calcination procedure, and high doses of ionizing radiation, PDVBVIM1.5SO₃ maintained its structural integrity and outstanding performance. Additionally, PDVBVIM1.5SO₃ displayed outstanding adsorption efficiency toward a simulated Hanford low-activity waste stream with ReO₄^–. This work demonstrates that achieving a balance between hydrophobicity and hydrophilicity in an exchange resin is of great significance for enhancing the selection and removal of TcO₄^–/ReO₄^–, and PDVBVIM1.5SO₃ resin could be an excellent acid nuclear waste-adsorbing material candidate.