ION-EXCHANGE SELECTIVITY FOR ALKALI METAL IONS ON A CRYPTOMELANE-TYPE HYDROUS MANGANESE DIOXIDE |
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| Authors: | Masamichi Tsuji,Sridhar Komarneni,Mitsuo Abe |
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| Affiliation: | 1. Department of Chemistry , Faculty of Science Tokyo Institute of Technology , 2-12-1, Ookayama, Meguro-ku, Tokyo 152, Japan;2. Department of Agronomy Materials Research Laboratory , The Pennsylvania State University , University Park, PA, 16802, USA |
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| Abstract: | ABSTRACT A cryptomelane-type hydrous manganese dioxide in the H+ form has been studied for its ion-exchange selectivity for Li+, Na+, K+, Rb+ and Cs+/H+ exchange at 30*C. The distribution coefficients for each alkali cation were calculated as a function of the initial concentration of exchanging cations in the presence of a constant total normality of 0.1 N. The separation factor for the Na+ - K+ pair attained 1.3 x 10" at Xx→0 This extremely high selectivity can be attributed to the rigid tunnel structure with an opening which is only accessible to less hydrated cations, those that shed their hydration shell easily and those with crystal ionic radius of approximately 1.4A. |
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