• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.72-75
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• 2003

Plant species have shown the capability to absorb U into the biomass. Norman(l952) even suggested that uranyl ion acts as an accessory microelement in growth of Lemna and flax roots. The plants, termed metal hyperaccumulators, can extract and accumulate more than 1000-10,000mg heavy metal per kilogram of dry weight of plants (0.1-1%). The most vital main factors influencing the ability and efficiency of phytoremediation is the ability of the plant to uptake the metals from soil before the accumulation mechanism happens in the plant tissue. (omitted)

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.143-158
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• 1990

Metal complexes were prepared by reacting uranium (Ⅵ), thorium (Ⅳ) and rare earth metal (Ⅲ) ions including Nd (Ⅲ), Sm (Ⅲ) and Ho (Ⅲ) with macrocyclic ligands including five crown ethers, nine crownands and one cryptand ligands, and subjected to NMR studies in order to examine coordination sites of the ligands and compositions of the complexes formed. Among the marcocyclic ligands, crown ethers and crownand ligands have shown down-field shifts of the methylene protons of the lcigands by forming stable complexes with all the metal ions and the differences of chemical shifts were decreased as increasing of the cavity-size of crown ethers for the same metal ions and decreasing of the atomic number of the rare earth metals for the same ligands. It has been found that crownand 22 gave a stable complex with uranium(Ⅵ) ion by the coordination through both oxygen and nitrogen atoms of the ligand whereas no complex was formed with the rare earth metal(Ⅲ) ions, which on the other hand were found to form stable complexes with cryptand 221. The rest of the crowand ligands have also been found to form stable complexes with uranium(Ⅵ) ion by coordinating through all the oxygen and nitrogen atoms of the ligands whereas no complexes were formed with the rare earth metal(Ⅲ) ions. It has also been shown by 1H-NMR study that uranium(Ⅵ), thorium(Ⅳ) and rare earth metal(Ⅲ) ions formed 1:1 complexes with the macrocyclic ligands except for thorium(Ⅳ) complex of 12C4 in which the mole ratio of metal to ligand is 1:2. More stable metal complexes show larger changes in chemical shifts of the coordinated ligand protons. Finally, the rare earth metal(Ⅲ) complexes of 18C6 have shown ligand exchange reaction with the solvent molecules in acetylacetone solution, which was not observed for the uranium (Ⅵ) complexes.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.238-238
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• 2003

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.451.2-451
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.310-310
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• 1998

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
• /
• pp.277.2-277
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
• /
• pp.282.2-282
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.445.2-445
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• 2002

• Journal of environmental and Sanitary engineering
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• v.20 no.4 s.58
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• pp.38-44
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• 2005

Cryptand resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of $1\%,\;2\%,\;5\%\;and\;10\%$ by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium$(UO_2^{2+})$ ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium$(UO_2^{2+})$ > zinc$(Zn^{2+})$ > samarium$(Sm^{3+})$ ion. The adsorption was in order of $1\%>2\%>5\%>10\%$ crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Journal of the Korean Society of Clothing and Textiles
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• v.14 no.2
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• pp.98-103
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• 1990

Fibrous adsorbents containing amidoxime group which make chelate complexes with uranyl ions are studied for the recovery of uranium from sea water. Acrylic fibers are used as base Polymer. The adsorption properties of uranium are carried out to examine pH effect, concen-tration dependence, adsorption rate, separation, and chelate complex. The results obtained are as follows; 1. Metal capacity of U (VI) ion is in the range of pH $2\~10.2$. Amidoxime group-containing fiber recover U (VI) ions existed in sea water or waste water in extremely small quantities. 3. Using amidoxime group-containing fiber Cu (II) and U (VI) are separated with each other in dilute nitric acid solution (pH 2.3). 4. U (VI) chelate complexes are conformed by tridendate ligands, which are coordinated with one nitrogen and two oxygens onto amidoxime group-containing fiber.