A Family of Peroxo-titanate Materials Tailored for Optimal Strontium and Actinide Sorption

Achieving global optimization of inorganic sorbent efficacy, as well as tailoring sorbent specificity for target sorbates, would facilitate increased widespread use of these materials in applications such as producing potable water or nuclear waste treatment. Sodium titanates have long been known as sorbents for radionuclides, 90Sr and transuranic elements in particular. We have developed a related class of materials, which we refer to as peroxo-titanates. These are sodium titanates or hydrous titanates synthesized in the presence of, or treated postsynthesis with, hydrogen peroxide. Peroxo-titanates show remarkable and universal improved sorption behavior with respect to separation of actinides and strontium from Savannah River Site (SRS) nuclear waste simulants. Enhancement in sorption kinetics can potentially result in as much as an order of magnitude increase in batch processing throughput. Peroxo-titanates have been produced by three different synthetic routes: postsynthesis peroxide treatment of a commercially produced monosodium titanate, an aqueous-peroxide synthetic route, and an isopropanol-peroxide synthetic route. The peroxo-titanate materials are characteristically yellow to orange, indicating the presence of protonated or hydrated Ti-peroxo species; the chemical formula can be generally written as H v Na w Ti2O5·(xH2O)[yH z O2], where (v + w) = 2, z = 0−2, and total volatile species accounts for 25−50 wt % of the solid. Further enhancement of sorption performance is achieved by processing, storing, and utilizing the peroxo-titanate as an aqueous slurry rather than a dry powder and by postsynthesis acidification. All three synthesis modifications, addition of hydrogen peroxide, use of a slurry form, and acidification, can be applied more broadly to the optimization of other metal oxide sorbents and other ion separations processes.