PNNL

Abstract

Using our self-assembled silanol technology, we developed eight functional nanoporous silica sorbents for capturing two classes of radionuclides: the actinide uranium (U), thorium (Th), plutonium (Pu), americium (Am) and the transition metal cobalt (Co). We tested them in sea, ground, and river water that were adjusted to pH 0-8.0 and doped with competing metals (Mg, Ca, K, Se, Mn, Fe, Co, Cu, Zn, and Mo) at levels encountered in environmental or physiological samples. Sorbents having three analogs of hydroxypyridinones (HOPO) and acetamide phosphonate (Ac-Phos) were exceptional at capturing U, Th, and Pu from pH 2.0 to 8.0, and very good at capturing Am from pH 5.0 to 8.0 with the affinity ranged from 3,4-HOPO > 1,2-HOPO > 3,2-HOPO > Ac-Phos. However, the affinity is reversed at near zero pH. For capturing Co, a family of glycine derivatives on nanoporous silica has been developed and the affinity for Co ranged from IDAA ~ DE4A > ED3A between pH 5.0-8.0. Our materials significantly outperformed the commercially available cation sorbents such as Chelex-100 and activated carbon in terms of binding affinity and rate; thus demonstrating great potential to be used as decorporation agents for water treatment and recovery of valuable actinides.