PNNL

Abstract

The modulation of defect-controlled leaching kinetics of a radionuclide and radionuclide surrogate from metal-organic frameworks (MOFs) was probed for the first time and compared with porous functionalized silica-based materials, revealing an unprecedented re-adsorption phenomenon. On a series of zirconium-based MOFs as model systems, we demonstrated the ability to capture and retain >99% of the transuranic 241Am radionuclide after one week of storage. We report the possibility to tailor radionuclide release kinetics in MOFs through framework defects as a function of postsynthetically installed organic ligands including cationchelating crown-ether-based linkers. Based on comprehensive analysis using spectroscopy (extended X-ray absorption fine structure, UV-vis, Fourier-transform infrared, inductively coupled plasma mass spectrometry, NMR), X-ray crystallography (single crystals and powders), and theoretical calculations (nine kinetics models and structure simulations), we demonstrate that synergy of radionuclide integration methods, topological restrictions, postsynthetic scaffold modification, and defect engineering, a combination that is inaccessible in any other platform, could be used for fine tuning and fundamental studies of radionuclide leaching kinetics; resulting in the possibility to advance the nuclear waste administration sector.