An advanced separation method for the acquisition of 212Pb/212Bi from natural thorium

212Pb/212Bi hold significant potential for targeted cancer therapy; however, their supply remains severely limited. The extraction of 212Pb/212Bi from natural thorium is expected to fundamentally address this issue. This study proposes and verifies a new, efficient and low-cost method for separating 212Pb/212Bi from natural 232Th by investigating the separation behavior and mechanism of a silica-supported anion exchange resin (SiPyR-N4) toward multiple types of metal cations in hydrochloric solution. The experimental results demonstrated that SiPyR-N4 was successfully prepared with a uniform shape, porous structure, and containing quaternary amines. SiPyR-N4 showed extremely high selectivity for Pb2+ and Bi3+, but no affinity for Th4+, La3+, and Ba2+. The adsorption speed was more than six times as fast as traditional resins, providing significant advantages in the separation of short-lived nuclides. The hot separation experiment suggested that 212Pb and 212Bi were successfully isolated from natural 232Th by using natural thorium as the raw material, and the long-lived nuclides were removed completely. The selective separation mechanism was attributed to Pb2+ and Bi3+ forming anionic complexes in the hydrochloric acid medium, while Th4+, Ra2+, and Ac3+ did not form such complexes. Pb2+ and Bi3+ were bound to the active sites via chloride bridges, with [PbCl3]- and [BiCl6]3- serving as the main adsorbed species. This study is the first to report the direct and selective separation of 212Pb and 212Bi from 232Th decay chains using non-crown ether materials, and it provides an excellent material candidate for the separation of short-lived nuclides, showing significant application potential in the future.