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Author Jin, Z.; Külls, C.
Title FDM based OA-ICOS for high accuracy 13C quantification in gaseous CO2 Type Journal Article
Year 2020 Publication Earth and Environmental Science Abbreviated Journal EES
Volume (down) 446 Issue 3 Pages 032061
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Call Number THL @ christoph.kuells @ Jin2020fdm Serial 16
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Author Jana, A.; Unni, A.; Ravuru, S.S.; Das, A.; Das, D.; Biswas, S.; Sheshadri, H.; De, S.
Title In-situ polymerization into the basal spacing of LDH for selective and enhanced uranium adsorption: A case study with real life uranium alkaline leach liquor Type Journal Article
Year 2022 Publication Chemical Engineering Journal Abbreviated Journal
Volume (down) 428 Issue Pages 131180
Keywords In-situ polymerization, Layered double hydroxide, Leach liquor, Uranium adsorption, Uranium recovery
Abstract Uranium is used as a fuel for nuclear power plant and can be extracted from different ores, mainly acidic (silicious ore) and alkaline (carbonate ore). Recovery of uranium through acid leaching from silicious ore is well established, whereas, alkaline leaching from carbonate ore is challenging due to the excessive salinity of leach liquor and high concentration of carbonate, bicarbonate and sulphate. Herein, two monomers, acrylic acid (AA) and N, N-methylene bisacrylamide (BAM), selective towards uranyl were intercalated in-situ into the interlayer, followed by their polymerization and cross-linking to form novel polymer intercalated hybrid layered double hydroxide (LDH). The LDH acts as a backbone to overcome coiling and swelling of polymer and anchors them as free-standing. Various parameters, like, the type of metal ions, monomer ratio (AA: BAM) and metal ion ratio (M2+:M3+), were studied to determine the optimum conditions for effective intercalation and polymerization of monomers. Magnesium aluminum (MgAl) LDH with a cross-linked polymer having a monomer ratio of 3:2 (AA: BAM) as intercalating species showed maximum efficiency of uranyl adsorption (1456 mg/g at 30 °C) with highest capacity so far. The distribution coefficient (Kd, l/mg) in the order of 105 suggested that the adsorbent was highly selective for uranyl in the presence of different cations, anions and humic acid. The adsorbent extracts uranium effectively and selectively from a real-life alkaline leach liquor with an efficiency of 96% at 5 g/l dose. Uranium can be recovered from the adsorbent in the form of sodium di-uranate using 2(M) NaOH and was reused for eight cycles.
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ISSN 1385-8947 ISBN Medium
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Call Number THL @ christoph.kuells @ jana_-situ_2022 Serial 209
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Author Morin, E.; Grodek, T.; Dahan, O.; Benito, G.; Külls, C.; Jacoby, Y.; Van Langenhove, G.; Seely, M.; Enzel, Y.
Title Flood routing and alluvial aquifer recharge along the ephemeral arid Kuiseb River, Namibia Type Journal Article
Year 2009 Publication Journal of Hydrology Abbreviated Journal
Volume (down) 368 Issue 1-4 Pages 262-275
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Publisher Elsevier Place of Publication Editor
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Call Number THL @ christoph.kuells @ Morin2009flood Serial 26
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Author Gómez, P.; Garralón, A.; Buil, B.; Turrero, M.J.; Sánchez, L.; Cruz, B. de la
Title Modeling of geochemical processes related to uranium mobilization in the groundwater of a uranium mine Type Journal Article
Year 2006 Publication Science of The Total Environment Abbreviated Journal
Volume (down) 366 Issue 1 Pages 295-309
Keywords Geochemical modeling, Granite, Groundwater, Uranium mine, Uranium retention
Abstract This paper describes the processes leading to uranium distribution in the groundwater of five boreholes near a restored uranium mine (dug in granite), and the environmental impact of restoration work in the discharge area. The groundwater uranium content varied from \textless1 μg/L in reduced water far from the area of influence of the uranium ore-containing dyke, to 104 μg/L in a borehole hydraulically connected to the mine. These values, however, fail to reflect a chemical equilibrium between the water and the pure mineral phases. A model for the mobilization of uranium in this groundwater is therefore proposed. This involves the percolation of oxidized waters through the fractured granite, leading to the oxidation of pyrite and arsenopyrite and the precipitation of iron oxyhydroxides. This in turn leads to the dissolution of the primary pitchblende and, subsequently, the release of U(VI) species to the groundwater. These U(VI) species are retained by iron hydroxides. Secondary uranium species are eventually formed as reducing conditions are re-established due to water–rock interactions.
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ISSN 0048-9697 ISBN Medium
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Call Number THL @ christoph.kuells @ gomez_modeling_2006 Serial 162
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Author Klaus, J.; Külls, C.; Dahan, O.
Title Evaluating the recharge mechanism of the Lower Kuiseb Dune area using mixing cell modeling and residence time data Type Journal Article
Year 2008 Publication Journal of Hydrology Abbreviated Journal
Volume (down) 358 Issue 3-4 Pages 304-316
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Publisher Elsevier Place of Publication Editor
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Notes Approved no
Call Number THL @ christoph.kuells @ Klaus2008evaluating Serial 28
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