Sorption and desorption performance of La3+/Bi3+ by surface-modified activated carbon for potential application in medical 225Ac/213Bi generators

²¹³Bi is a promising candidate for targeted alpha therapy. However, the search for suitable materials to separate clinically relevant activities of ²¹³Bi from its parent ²²⁵Ac remains an ongoing yet critical challenge. This study evaluates sulfonated Norit CA1 (activated carbon) materials (SNCAs) as alternative sorbents for use in ²²⁵Ac/ ²¹³Bi radionuclide generators and gives an overview of their simultaneous sorption/desorption performance towards La ³⁺ and Bi ³⁺. The SNCAs exhibit high and selective uptake of Bi ³⁺ in the presence of NaNO ₃ at low pH values. In contrast, the sorption performance for La ³⁺ (which was certified as a non-radioactive surrogate for ²²⁵Ac ³⁺) onto SNCAs was more sensitive to the salt concentrations and pH values. The desorption results show that an efficient elution of Bi ³⁺ from SNCAs is achieved using HCl, NaI or NaCl solutions. The experimental sorption data are analysed by various kinetic and isotherm models. The SNCAs exhibit high radiolytic stability, fast sorption kinetics, good durability and recyclability for La ³⁺/Bi ³⁺. This research indicates that SNCAs with sufficient oxygen-containing groups are promising sorbents for the separation of ²¹³Bi in an inverse ²²⁵Ac/ ²¹³Bi radionuclide generator.