A Preliminary Study of Spherical Surface-Modified Carbon Materials for Potential Application in La (Ac) and Bi Separation.

Separation of high-activity Bi from Ac for targeted alpha therapy is challenging due to the instability of existing sorbents. Surface-modified carbon materials have shown promise for use in inverse Ac/Bi generators. However, previously reported materials with irregular shapes may limit their applications in column separations. In contrast, spherical particles are expected to be more suitable for column chromatography compared to irregular powders as they can ensure uniform flow patterns, lower pressure drop, and effective packing. To address this limitation, a method was developed for the synthesis of spherical carbon beads via the carbonization of cellulose beads. Subsequently, surface modification on the spherical carbon beads was performed via sulfonation or oxidation of the carbon beads. Batch sorption experiments were conducted to assess their selective sorption toward Bi over La (as a surrogate of Ac) by varying the concentrations of HNO and NaNO. It was found that the selective sorption of Bi onto spherical surface-modified carbon beads could be achieved by adjusting the concentrations of HNO and NaNO. Furthermore, the sorption capacity of Bi decreased as the concentration of HCl increased due to the formation of bichloride complexes and the H competition. This implies that Bi can be effectively eluted from the spherical surface-modified carbon beads when using HCl as the eluate. Consequently, spherical surface-modified carbon beads show potential as alternative adsorbents for inverse Ac/Bi generators.