Nanospace Decoration with Uranyl-Specific “Hooks” for Selective Uranium Extraction from Seawater with Ultrahigh Enrichment Index

Abstract

Mining uranium from seawater is highly desirable for sustaining the increasing demand for nuclear fuel; however, access to this unparalleled reserve has been limited by competitive adsorption of a wide variety of concentrated competitors, especially vanadium. Herein, we report the creation of a series of uranyl-specific “hooks” and the decoration of them into the nanospace of porous organic polymers to afford uranium nanotraps for seawater uranium extraction. Manipulating the relative distances and angles of amidoxime moieties in the ligands enabled the creation of uranyl-specific “hooks” that feature ultrahigh affinity and selective sequestration of uranium with a distribution coefficient threefold higher compared to that of vanadium, overcoming the long-term challenge of the competing adsorption of vanadium for uranium extraction from seawater. The optimized uranium nanotrap (2.5 mg) can extract more than one-third of the uranium in seawater (5 gallons), affording an enrichment index of 3836 and thus presenting a new benchmark for uranium adsorbent. Moreover, with improved selectivity, the uranium nanotraps could be regenerated using a mild base treatment. The synergistic combination of experimental and theoretical analyses in this study provides a mechanistic approach for optimizing the selectivity of chelators toward analytes of interest.

Ultrahigh Affinity and Selectivity Nanotraps for Uranium Extraction from Seawater

“…Now, in terms of uranium selectivity, Ma and his collaborators proposed a new strategy of nanotraps with uranyl-specific “hooks” that pave the way for overcoming the long-term challenges of competitive adsorption of vanadium in uranium extraction from seawater. 1 …”

“…In their latest work, 1 they improved the strategy of cooperative binding. The uranyl-specific ligand “hooks” were created by precisely manipulating the chelators at the molecular level to enhance uranium selectivity.…”

“… Porous frameworks constructed by uranyl-specific ligand “hooks”. Reproduced from ref ( 1 ). Copyright 2021 The Authors.…”

“…(c) The distribution coefficient ( K d ) values for uranium and vanadium over various sorbent materials (cyan, uranium; red, vanadium). Reproduced from ref ( 1 ). Copyright 2021 The Authors.…”

“…However, the very low uranium concentration (∼3 ppb), numerous competing metal ions, especially vanadium ions, and microbial accumulation make it extremely difficult to exploit uranium from seawater. Now, in terms of uranium selectivity, Ma and his collaborators proposed a new strategy of nanotraps with uranyl-specific “hooks” that pave the way for overcoming the long-term challenges of competitive adsorption of vanadium in uranium extraction from seawater …”