A category of hierarchically porous tin (IV) phosphonate backbone with the implication for radioanalytical separation

• The rare occurrence of porous tin phosphonates as radionuclide scavengers was initiated.
• The hierarchical porous structure and inherent backbone functionality were explored.
• The competitive sequestration of radionuclide surrogates was performed in acidic media.
• The distinctive uptake profiles could be adopted for radioanalytical separation.

A category of tin (IV) phosphonate, prepared by nonionic templating and solvothermal treatment, has been utilized to sequester lanthanides and actinides from a multitude of radionuclide surrogates. The multi-porosity encompassing micro-, meso-, macro- and available phosphonic acid moieties, assembling into a novel inorganic–organic hybrid backbone, endow the aggregates of tin phosphonate nanoparticles with distinguishing uptake of trace surrogates. A distribution coefficient in the magnitude of 104, 105 mg L−1 could be obtained for uranyl and thorium (IV) in moderate acidic media, which far exceed the uptake of lanthanides, strontium and aluminum. However, the trivalent iron was also significantly retained, behaving similarly to the light actinides. The surrogate radionuclides would be readily scavenged by the porous backbone within 8 h. Based on the affinity discrepancy in the nitric acid gradient and competitive adsorption kinetics, simple radioanalytical separations have been proposed utilizing these tin phosphonates to achieve preliminary enrichment of light lanthanides and actinides.

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