An overview and recent progress in the chemistry of uranium extraction from seawater

Abstract

This review provides a brief background on the extraction of uranium from seawater as well as recent work by the United States Department of Energy on this project. The world's oceans contain uranium at 3 parts per billion, and despite this low concentration, there has been historical interest in harvesting it, mainly in Japan in the 1980s and the United States in this decade. Improvements in materials, chemistry, and deployment methods have all been made, with the ultimate goal of lower cost. This has been partially realized, dropping from approximately $2000 per kg UO extracted in 1984 to $500 per kg today, although this is not yet competitive with terrestrial uranium. This technology may become cost-competitive if the cost of land-based uranium rises, especially if seawater extraction technology is improved further. The coordination chemistry aspects of the project are described in more detail, exploring the functional groups that are present on typical polymer sorbents as well as small-molecule analogues of these ligands. Selectivity for uranium over other metals, particularly vanadium, remains problematic, and techniques to both quantify binding strength and selectivity in order to overcome this issue are essential for future cost improvements.

Significantly Enhanced Uranium Extraction from Seawater with Mass Produced Fully Amidoximated Nanofiber Adsorbent

“…Great efforts have been made to develop clean energy as alternatives to fossil fuels. [19][20][21][22][23][24][25][26][27] Very recently, Cui and co-workers reported the application of an amidoxime-functionalized electrode in a half-wave rectified alternating current electrochemical (HW-ACE) method for the extraction of uranium from seawater. [3] With DOE direction, the uranium uptake capacity of fiber adsorbents in natural seawater has more than tripled in five years.…”

“…[3,[26][27][28][29][30] Radiation-induced graft polymerization (RIGP) and atom-transfer radical polymerization (ATRP) strategies were commonly used to graft acrylonitrile monomer to some robust backbone polymer fibers, typically polyethylene (PE) fibers, to form polyacrylonitrile (PAN) grafted fabric, followed with the postamidoximation to convert nitrile groups to amidoxime groups. [3,[26][27][28][29][30] Radiation-induced graft polymerization (RIGP) and atom-transfer radical polymerization (ATRP) strategies were commonly used to graft acrylonitrile monomer to some robust backbone polymer fibers, typically polyethylene (PE) fibers, to form polyacrylonitrile (PAN) grafted fabric, followed with the postamidoximation to convert nitrile groups to amidoxime groups.…”

“…Uranium extraction from seawater via fiber adsorption has recently seen significant progress since the US Department of Energy (DOE) has become involved . With DOE direction, the uranium uptake capacity of fiber adsorbents in natural seawater has more than tripled in five years . Very recently, Cui and co‐workers reported the application of an amidoxime‐functionalized electrode in a half‐wave rectified alternating current electrochemical (HW‐ACE) method for the extraction of uranium from seawater .…”

The Effect of Guest Metal Ions on the Reduction Potentials of Uranium(VI) Complexes: Experimental and Theoretical Investigations

“…[21][22][23][24][25][26][27] The studies of these properties of uranium are helpful for waste managementi nn uclear reactors to prevent water and soil pollution.Uranium forms stable com-plexes with multidentate organic ligands, af act that is exploited in the detection and separation of uranium from nuclear slag, ground water,a nd seawater. [28][29][30][31] It shows multiple oxidation states, varying from + III to + VI;h owever,i na erobic conditions the commono xidation state is + VI, which is stabilized as the uranyl dication (UO 2 2 + ). [32][33][34][35][36][37][38][39] Ac onvenient method for the synthesis of U V compounds is to reduce the corresponding U VI speciese lectrochemically.…”

Preparation of ZnO nanoparticle loaded amidoximated wool fibers as a promising antibiofouling adsorbent for uranium(vi) recovery

“…Amidoxime groups based adsorbents have been reported showing good selectivity toward uranium, therefore, various matrixes have been functionalized with amidoxime groups for uranium adsorption including polymeric bers, hydrogels, metal organic frameworks, and natural biopolymers. [8][9][10] Amidoxime functionalized wool bers have been developed for recovery of uranium due to its good hydrophilicity and good physical stability. [10][11][12][13] Recently, the problem of biofouling in decreasing adsorption performance and the corrosion of adsorbent has been noted by Park et al 14 and Hu et al 15 Due to the concentration of uranium in seawater is critical low, the adsorbents were immersed in the seawater usually for several weeks.…”