High-Capacity Amidoxime-Functionalized β-Cyclodextrin/Graphene Aerogel for Selective Uranium Capture

Abstract

Uranium extraction from seawater is a grand challenge of mounting severity as the energy demand increases with a growing global population. An amidoxime-functionalized carboxymethyl β-cyclodextrin/graphene aerogel (GDC) is developed for highly efficient and selective uranium extraction via a facile one-pot hydrothermal process. GDC reaches equilibrium in 1 h, and the maximum adsorption capacity calculated from Langmuir model is 654.2 mg/g. Benefiting from the chelation and complexation reaction, the obtained GDC has an excellent selectivity even when the competitive cations, anions, and oil pollutants exist. In addition, the aerogel possesses great mechanical integrity and remains intact after 10 compression cycles. Meanwhile, the GDC can be easily regenerated and maintains a high reusability of 87.3% after 10 adsorption−desorption cycles. It is worthwhile to mention that GDC exhibits an excellent extraction capacity of 19.7 mg/g within 21 days in natural seawater, which is greatly desired in uranium extraction from seawater.

An amyloid-like proteinaceous adsorbent for uranium extraction from aqueous medium

“…[29][30][31][32][33][34] The main reason for the high selectivity towards uranium ions is that b-CD has a higher binding free energy for uranium ions (À29.95 kcal mol À1 ) compared to other metal ions (e.g., Li, À14.45 kcal mol À1 ; Na, À15.51 kcal mol À1 ; K, À17.43 kcal mol À1 ; Rb, À19.01 kcal mol À1 ; Mg, À26.99 kcal mol À1 ; Ca, À22.76 kcal mol À1 ; Sr, À23.61 kcal mol À1 ; Ba, À26.84 kcal mol À1 ). 46,47 In addition to metal cations, the effect of the most common concomitant anions including Cl À , CO 3 2À , NO 3 À and SO 4 2À on uranium ion adsorption was also studied. As shown in Fig.…”

“…[42][43][44][45] Compared to other common metal ions, the b-CD exhibits superior adsorption and selectivity to uranium ions owing to the higher binding free energy. 46,47 Accordingly, many b-CD based adsorbents have been of great interest and developed. [48][49][50] The relatively good water solubility of b-CD certainly limits its application in metal extraction as an adsorbent individually; thus, b-CD must be combined with water insoluble carriers, including carbon nanotubes, graphene oxide, graphene aerogel, graphite carbon nitrogen (g-C 3 N 4 ), PAN membranes, magnetic iron oxide, Al(OH) 3 , titanium dioxide, montmorillonite and so on, 46,47,[51][52][53][54][55][56][57][58][59][60] with the aim to isolate metal loaded adsorbents from solution.…”

“…46,47 Accordingly, many b-CD based adsorbents have been of great interest and developed. [48][49][50] The relatively good water solubility of b-CD certainly limits its application in metal extraction as an adsorbent individually; thus, b-CD must be combined with water insoluble carriers, including carbon nanotubes, graphene oxide, graphene aerogel, graphite carbon nitrogen (g-C 3 N 4 ), PAN membranes, magnetic iron oxide, Al(OH) 3 , titanium dioxide, montmorillonite and so on, 46,47,[51][52][53][54][55][56][57][58][59][60] with the aim to isolate metal loaded adsorbents from solution. Even though these b-CD based adsorbents present good adsorption capacity and selectivity for uranium ions, the preparation process is complicated, and toxic organic reagents are oen required; besides, water insoluble carriers are costly, nonrenewable and nondegradable.…”

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

“…Oceans are the Earth’s largest reservoirs of uranium, which is more abundant in seawater than on land by several orders of magnitude; extracting this uranium can help in sustaining nuclear power production for millennia. 12 − 21 Efficient extraction of the potential uranium resources in seawater requires the use of highly selective sorbent materials for accumulating uranium. Although the development of efficient uranium adsorbents has been an elusive quest since the 1960s, its pace has slowed.…”

“…Significant efforts must be made in this regard to enable an energy revolution. − Among the numerous potential energy technologies, nuclear energy has proven to be a valid alternative to fossil fuels. − Uranium mining is essential to ensure long-term viability of nuclear power. Oceans are the Earth’s largest reservoirs of uranium, which is more abundant in seawater than on land by several orders of magnitude; extracting this uranium can help in sustaining nuclear power production for millennia. − Efficient extraction of the potential uranium resources in seawater requires the use of highly selective sorbent materials for accumulating uranium. Although the development of efficient uranium adsorbents has been an elusive quest since the 1960s, its pace has slowed.…”