Rapid and scalable preparation of highly quaternized polymer networks to achieve efficient simultaneous adsorption of iodide and pertechnetate

Abstract

The efficient separation of fission products, such as TcO₄⁻ and I⁻, holds strategic significance for the management of radioactive wastes and environmental protection. In this study, we propose an ultrafast strategy for scalable preparation of a highly quaternized organic network to facilitate efficient and synchronous separation of iodide and pertechnetate. The network can be prepared within a few minutes at room temperature, using polyethylenimine and 1,2,4,5-tetrakis(bromomethyl)benzene as building blocks. After chlorine replacement, the network, abundantly decorated with quaternary ammonium groups (Cl@QPN), exhibits an ultrahigh positive charge density of 7.6 mmol/g. This enables the rapid and efficient enrichment of target anions through strong electrostatic Coulomb interactions. As a result, Cl@QPN exhibits significantly higher adsorption rate constants of 0.830 g/(mg min) for ReO₄⁻ (a nonradioactive surrogate of TcO₄⁻) and 0.677 g/(mg min) for I⁻ compared to other materials. Furthermore, it possesses high adsorption capacities, reaching 1,681 mg/g for ReO₄⁻ and 917.4 mg/g for I⁻. Cl@QPN also demonstrates good selectivity towards target ions and shows efficient adsorption for ⁹⁹TcO₄⁻. Additionally, Cl@QPN exhibits high dynamic processing capacities, handling up to 3,100 and 7,400 kg of simulated streams per kilogram of material for I⁻ and ReO₄⁻, respectively.