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O
-pentadentate planar ligands designed for the strongest and selective capture of uranium from seawaterMizumachi, Takumi*; Sato, Minami*; Kaneko, Masashi; Takeyama, Tomoyuki*; Tsushima, Satoru*; Takao, Koichiro*
Inorganic Chemistry, 61(16), p.6175 - 6181, 2022/04
Times Cited Count：2 Percentile：36.89(Chemistry, Inorganic & Nuclear)Based on unique 5-fold equatorial coordination of UO
, water-compatible pentadentate planar ligands, Hsaldian and its derivatives, were designed as strong and selective capture of UO in seawater. In the simulated seawater condition (0.5 M NaCl + 2.3 mM HCO
/CO
, pH 8), saldian shows the strongest complexation with UO to form UO(saldian) (log
= 28.05 
0.07), which is more than 10 order of magnitude greater than amidoxime-based or -inspired ligand systems most commonly employed for U capture from seawater. Good selectivity for UO from other metal ions coexisting in seawater was also demonstrated.
Seko, Noriaki; Kasai, Noboru; Shimizu, Takao*; Tamada, Masao
Nihon Kaisui Gakkai-Shi, 59(5), p.316 - 319, 2005/10
Braid adsorbent having functional group of amidoxime is a promising material for the recovery of uranium dissolved in the seawater. This long braid adsorbent was made by polyethylene multi-fibers in which amidoxime groups were introduced by radiation-induced graft polymerization and subsequent chemical treatment. The braid adsorbent obtained was moored at the offing of Okinawa Island. The average U adsorption of the adsorbent became 1.5 g-U/kg-adsorbent for 30 d soaking. The mooring system for braid adsorbent has possibility which reduced the cost for the recovery of uranium from seawater. Annual product of 1200 tons of uranium needs 134 km
of mooring area. In addition, there is 6000 km and more of suitable sea area for the collection of the uranium in the regions from Okinawa Islands to Tosa Bay in Japan.
Tamada, Masao; Seko, Noriaki; Kasai, Noboru; Shimizu, Takao*
FAPIG, (169), p.3 - 12, 2005/03
Braid adsorbent having functional group of amidoxime is a promising material for the recovery of uranium dissolved in the seawater. This braid adsorbent was made by polyethylene multi-fibers in which amidoxime groups were introduced by radiation-induced graft polymerization and subsequent chemical treatment. Reaction time for graft polymerization was 5 h and the resulted braid adsorbent had 2.8 mmol/g-adsorbent of amidoxime group. The braid adsorbent obtained was moored at the offing of Okinawa Island. The adsorption of uranium reached 1.5g/kg-adsorbent for 30 d soaking. The mooring system for braid adsorbent has possibility which reduced the cost for the recovery of uranium from seawater. It is shown that 134 km of mooring area is needed for annual product of 1200 tons of uranium. In addition, there is 6000 km and more of suitable sea area for the collection of the uranium in the regions from Okinawa Islands to Tosa Bay in Japan.
Tamada, Masao; Seko, Noriaki; Yoshii, Fumio
Radiation Physics and Chemistry, 71(1-2), p.223 - 227, 2004/09
Times Cited Count：71 Percentile：96.47(Chemistry, Physical)Graft polymerization and crosslinking in radiation processing were attractive techniques to modify conventional polymers. In the case of graftpolymerization, metal adsorbent was prepared by introducing the chelate function to trunk polymer like polyethylene. The obtained metal adsorbent was applied to the recovery of uranium in seawater. Three years' marine experiment revealed that 1kg of uranium could be collected by using graft-adsorbent. Natural polymers such as derivatives of starch and cellulose led irradiation crosslinking at paste-like condition and formed hydrogels. These hydrogels had degradability even after crosslinking. The mat of degradable hydrogel was effective to prevent bedsores as a healthcare product. After use, the hydrogel can be converted to fertilizer by decompositions.
Shimizu, Takao*; Tamada, Masao
Kaiyo Kaihatsu Rombunshu, 20, p.617 - 622, 2004/06
Recovery system of braid type adsorbent which stands straight with built-in float from sea bottom was proposed on the points of effective and economical view. The system scale for 1200 t/y recovery (demand for 6 atomic power plants) with braid type adsorbent was optimized by a model in which the efficiency of uranium adsorption was proportional to the uranium concentration surrounding the adsorbent. The recovery system of 2.67 millions adsorbents which were arranged with the distance of more than 60m intervals among the adsorbents could collect 1200t/y uranium. The system still collected 1000 t/y uranium when the interval distance decreased to 4 m. The area occupied by the adsorbents was 6.5 km square. The sea area on the coast of Japan was searched for recovery system of braid type adsorbent by considering the factors of the temperature, the depth, the fishery, and the territorial waters of Japan. The selected sea area was located form the South East Islands to the offing of Koch in the depth range from 100m to 200m, where the Japan Current flew.
Tamada, Masao
Genshiryoku Hyakka Jiten ATOMICA (Internet), 15 Pages, 2004/04
no abstracts in English
Shimizu, Takao*; Tamada, Masao; Seko, Noriaki; Sakaguchi, Isamu*
Kaiyo Kaihatsu Rombunshu, 18, p.737 - 742, 2002/06
Total amount of uranium in seawater is 4.5 billion tons corresponding to 45,000 times of annual demand for nuclear fuel in the world, though its concentration is only 3.3 mg/m3. The target of this study is that the cost-down of uranium collection from the sea to three times of the market price. This price is cheaper than the recycle fuel by nuclear reprocessing. The present study proposed a high performance adsorbent made by means of both radiation induced graft polymerization and braid technique. The drag force of the braid type adsorbent in water channel was measured. In the west coast of Okinawa prefecture, the adsorption of uranium and the adhesion of sea creature were investigated. It was clarified that reduction of the drag force by the deformed braid adsorbent in the water flow, the increment of uranium adsorption owing to high temperature of seawater, and little adhesion of the creature.
Sugo, Takanobu; Tamada, Masao; Seguchi, Tadao; Shimizu, Takao*; Uotani, Masaki*; Kashima, Ryoichi*
Nihon Genshiryoku Gakkai-Shi, 43(10), p.1010 - 1016, 2001/10
Times Cited Count：16 Percentile：73.21(Nuclear Science & Technology)The cost of uranium recovered from seawater was estimated by using the amidoxime adsorbent of polymer fibers synthesized by radiation modification, and the technical problems in the recovery system were extracted. The cost of adsorbent materials, storage in seawater for uranium absorption, and the uranium detachment from the adsorbent was estimated respectively in three different systems of the storage in seawater as a buoy, floating body, and chain binding system. The recovery cost of uranium from seawater was estimated to be 8
10 times of that from mine uranium. More than 80% of the total cost was occupied by the cost for storage in seawater, which is owing to a weight of metal cage for the holding of adsorbents. The cost can be attained to half by the reduction of the weight to 1/4. One of facing research subject is the improvement of adsorbent ability, since the cost directly depends on the adsorbent performance.
Sugo, Takanobu; Saito, Kyoichi*
Nihon Genshiryoku Gakkai-Shi, 36(7), p.619 - 623, 1994/07
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
*; Saito, Kyoichi*; *; Furusaki, Shintaro*; Sugo, Takanobu; *
Industrial & Engineering Chemistry Research, 33(3), p.662 - 666, 1994/00
Times Cited Count：65 Percentile：93.91(Engineering, Chemical)no abstracts in English
Kaiyo Kagaku, 17(4), p.71 - 74, 1985/00
no abstracts in English
Takao, Koichiro*; Kaneko, Masashi; Tsushima, Satoru*
no journal, ,
Based on a unique structural character of uranyl ion which favors planar penta-dentate coordination style, we aim to develop advanced absorbent for uranium recovery from seawater. In this study, we designed penta-dentate ligands as the absorber moiety and performed the synthesis and characterization of the uranyl complexes with their ligands.
