Development of Selective Recovery System of Lithium from Deep Ocean Water Using A Novel MnO_2 Type Adsorbent

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For the purpose of efficient and selective separation and recovery of lithium from deep ocean water, we have carried out: (1)Development of novel λ type manganese dioxide (λ-MnO_2) adsorbents having high selectivity of lithium against sodium, (2)Evaluation of adsorption and separation performance of the λ-MnO_2 adsorbents, (3)Development of granulation method suitable for the λ-MnO_2 adsorbent preventing large pressure drop in the adsorption column of, and (4)Investigation of selective recovery system of lithium from the seawater using the column module. As a result of this research, the followings were obtained.(1)We have successfully developed λ-MnO_2 adsorbent which high-selectively recognizes lithium ion by eluting lithium from spinel type lithium manganese dioxide with aqueous hydrochloric acid. This result was applied to a Japanese patent (Patent pending 2002-46288), as, well as to the publication to journal and international conference.(2)We have carried out the separation of lithium ion from sodium ion using the λ-MnO_2 adsorbent. We have obtained the selectivity of lithium/sodium of over 800 times in case of batchwise method, while 2300 times selectivity in case of column separation method. This selectivity is the best all over the world.(3)We have prepared the granular adsorbents with some millimeter order using with chitin binder. We have observed the structures of granulated adsorbents with a scanning electron microscope as well as elucidated the crystal structure with X-ray diffractometer.(4)We have examined the influence of some experimental conditions on the selective recovery of lithium and sodium in artificial deep ocean water and real seawater in detail. We have obtained highly concentrated lithium solution from seawater under the adsorption-desorption operation of this column module system. This result was applied to the publication to journal and international conference.