Li^+に高選択吸着性を有する新しいTi系無機化合物

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A new inorganic titanium compound with high selective adsorbability for Li^+ was prepared by acid- treatment of precursory Li_2TiO_3- rich products synthesized by heating an equimolar mixture of powdered Li_2CO_3 and TiO_2 (anatase) in air at 450°- 950℃. These products were examined by X- ray diffraction, chemical analysis, specific surface area (BET method) , shape (TEM) and thermal (TG & DTA) analysis. For the examination of adsorbability for Li^+ on the products, adsorption of Li^+. Na^+, K^+ and Ca^<2+> for the acid- treated products was determined by a batch method in weakly basic media. The results are summarized as follows : (1) Crystalline Li_2TiO_3 transformed to a new crystalline phase ( TOH) , which was characterized by the XRD peaks at d = 4.74, 4.53 and 2.45 A^^゜ on acid-treatment. But the conversion decreased with increasing preparation temperature of the precursory products. (2) Li^+ was adsorbed selectively only on acid-treated products containing the TOH phase, suggesting that the TOH material contributed significantly to the selective adsorption of Li^+. (3) As the TOH phase contains TiO_2 and H_2O in the 1 : 1 molar ratio, it is considered that ・lithium-free titanium oxide hydride, H_2TiO_3, was formed from Li_2TiO_3 by the acid-treatment. (4) When the TOH adsorbs Li^+, a topotactic phase transformation to Li_2TiO_3 was observed. In the same manner as λ-MnO_2 , the following mechanism of cation exchange is supposed for the selective Li^+- adsorption on the TOH phase : TOH (H_2TiO_3)+2Li^+ →←Li_2TiO_3+2H^+. (5) The amount of adsorption of Li^+ on TOH was influenced by the texture. The specific surface area (SSA) of the acid- treated products depended remarkably on the preparation conditions of the precursory products. The ratios of the amount of adsorbed Li^+ to the exchange capacity increased with increasing SSA.
社団法人日本セラミックス協会の論文
1989-09-01

Li^+に高選択吸着性を有する新しいTi系無機化合物

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