2,6-Diiminopiperidin-1-ol: an overlooked motif relevant to uranyl and transition metal binding on poly(amidoxime) adsorbents

Kennedy, Zachary C.; Cardenas, Allan Jay P.; Corbey, Jordan F.; Warner, Marvin G.

doi:10.1039/c6cc02488b

Cited by 10 publications

(17 citation statements)

References 29 publications

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“…Similar multinuclear uranyl complexes were observed during crystallization of glutardiamidoxime with UO 2 (NO 3 ) 2 , where the metal nitrate induced in situ cyclization of the ligand to form a bridged dinuclear species (Figure 17). 132 While DFT and small molecule results are consistent with each other, it is worth noting they are performed under idealized conditions and may not be representative of a complex and dynamic system, as is the case for a polymer adsorbent deployed in seawater.…”

Section: Synthetic Polymersmentioning

confidence: 61%

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Materials for the Recovery of Uranium from Seawater

et al. 2017

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More than 1000× uranium exists in the oceans than exists in terrestrial ores. With nuclear power generation expected to increase over the coming decades, access to this unconventional reserve is a matter of energy security. With origins in the mid-1950s, materials have been developed for the selective recovery of seawater uranium for more than six decades, with a renewed interest in particular since 2010. This review comprehensively surveys materials developed from 2000-2016 for recovery of seawater uranium, in particular including recent developments in inorganic materials; polymer adsorbents and related research pertaining to amidoxime; and nanostructured materials such as metal-organic frameworks, porous-organic polymers, and mesoporous carbons. Challenges of performing reliable and reproducible uranium adsorption studies are also discussed, as well as the standardization of parameters necessary to ensure valid comparisons between different adsorbents.

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Section: Synthetic Polymersmentioning

confidence: 61%

“…The uranyl-binding ligand is formed by an in situ cyclization reaction of glutardiamidoxime prior to crystallization. Figure reprinted with permission from ref . Copyright 2016, Royal Society of Chemistry.…”

Section: Synthetic Polymersmentioning

confidence: 99%

Materials for the Recovery of Uranium from Seawater

et al. 2017

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“…Our data thus suggests that high Fe adsorption (Figure ) may cause much more pronounced amidoxime degradation. A recent report indicated that transition metals such as Cu(II) and Ni(II) can convert glutardiamidoxime, a single molecule surrogate of branch-chain amidoxime, to diiminopoperidin-1-ol under ambient conditions and may influence uranium adsorption by amidoxime ligand . The mechanism responsible for the Fe-induced amidoxime degradation and the subsequent poor adsorbent reusability are not clear and warrant further investigation.…”

Section: Resultsmentioning

confidence: 88%

“…A recent report indicated that transition metals such as Cu(II) and Ni(II) can convert glutardiamidoxime, a single molecule surrogate of branch-chain amidoxime, to diiminopoperidin-1ol under ambient conditions and may influence uranium adsorption by amidoxime ligand. 36 The mechanism responsible for the Fe-induced amidoxime degradation and the subsequent poor adsorbent reusability are not clear and warrant further investigation. On the other hand, the percent decreases of I 928 and I 1643 /I 1559 of AI8 adsorbent from humic acid-spiked seawater are only slightly higher than those from the unspiked seawater; the observed minor change in amidoxime abundance is reflected by the high reusability of AI8 under high HA conditions.…”

Section: Bicarbonate Elution For Adsorbent Regenerationmentioning

confidence: 99%

Assessment of Impacts of Dissolved Organic Matter and Dissolved Iron on the Performance of Amidoxime-Based Adsorbents for Seawater Uranium Extraction

Kuo

Pan

Strivens

et al. 2019

Ind. Eng. Chem. Res.

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One critical challenge of the development of seawater uranium extraction is to make uranium adsorbents perform well in the complex real seawater matrix, which is comprised of many competing ions and natural organic substances. Here, we conducted a systematic study using a continuous-flow seawater flume system to assess the potential impacts of dissolved organic matter (DOM) and dissolved iron on the uranium uptake performance, including adsorbent reusability, of amidoxime-based adsorbents. In the 28-day exposure, the adsorbent exposed in dissolved Fe-spiked seawater (low DOM/high Fe) and humic acid-spiked seawater (high DOM/high Fe) showed lower uranium adsorption loadings (73% and 56% of adsorption loading, respectively) than the same adsorbent exposed in seawater without spiking (low DOM/low Fe). The uranium adsorption loading of the reused adsorbent (after uranium stripping by a mild bicarbonate elution) in the dissolved Fe-spiked seawater dropped substantially to only 24% of the loading in the unspiked clean seawater counterpart, while not much change was observed in the performance of the adsorbent exposed to the humic acid-spiked seawater. Fourier transform infrared signatures of adsorbents suggest that the amidoxime ligands in the adsorbent exposed to dissolved Fe-spiked seawater had more severe degradation than the adsorbents exposed to humic acid-spiked seawater and unspiked clean seawater. Unlike the adsorbent exposed to dissolved Fe-spiked seawater, the adsorbent exposed to humic acidspiked seawater did not adsorb an elevated level of Fe compared to the adsorbent in the unspiked clean seawater. This suggests that the species of Fe in the humic acid-spiked seawater (primarily humic acid bound Fe) did not interact with the amidoximebased adsorbent, while the Fe species in the Fe-spiked seawater strongly interacted with the adsorbent and caused significant degradation of amidoxime ligands. On the other hand, highly variable uranium adsorption loadings were observed in the adsorbent in contact with humic acid-spiked seawater, but not in the adsorbents exposed to dissolved Fe-spiked seawater and seawater without spiking. Our observations indicate that seawater receiving high inputs of DOM and dissolved Fe, such as coastal waters, is not ideal for efficient extraction of uranium.

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“…This treatment process is also known to generate cyclic imide dioxime sites (TEVWAU) which have been ascribed with exceptional affinity for uranium as well, [28][29][30] as demonstrated by rigorous titration experiments by Rao, et al [31][32][33] Finally, work by Warner and colleagues articulated the metal-catalyzed cyclization of two adjacent amidoximes on glutardiamidoxime to form 2,6-diiminopiperidin-1-ol, and the subsequent uranium binding and crystallization to form oxo-bridged dinuclear uranyl complexes (ONILUU). 34 Fig. 1 displays representative crystal structures from the aforementioned small molecule studies.…”

mentioning

confidence: 99%

A report on emergent uranyl binding phenomena by an amidoxime phosphonic acid co-polymer

Abney

Das

Mayes

et al. 2016

Phys. Chem. Chem. Phys.

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The development of technology to harvest the uranium dissolved in seawater would enable access to vast quantities of this critical metal for nuclear power generation. Amidoxime polymers are the most promising platforms for achieving this separation, yet the design of advanced adsorbents is hindered by uncertainty regarding the uranium binding mode. In this work we use XAFS to investigate the uranium coordination environment in an amidoxime-phosphonic acid copolymer adsorbent. In contrast to the binding mode predicted computationally and from small molecule studies, a cooperative chelating model is favoured, attributable to emergent behavior resulting from inclusion of amidoxime in the polymer. Samples exposed to seawater also display a feature consistent with a μ(2)-oxo-bridged transition metal, suggesting the formation of an in situ specific binding site. These findings challenge long held assumptions and provide new opportunities for the design of advanced adsorbent materials.

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2,6-Diiminopiperidin-1-ol: an overlooked motif relevant to uranyl and transition metal binding on poly(amidoxime) adsorbents

Cited by 10 publications

References 29 publications

Materials for the Recovery of Uranium from Seawater

Materials for the Recovery of Uranium from Seawater

Assessment of Impacts of Dissolved Organic Matter and Dissolved Iron on the Performance of Amidoxime-Based Adsorbents for Seawater Uranium Extraction

A report on emergent uranyl binding phenomena by an amidoxime phosphonic acid co-polymer

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