複合吸着剤による海水中ウランの採取 Ｉ チタン系複合含水酸化物吸着剤のウラン吸着

Abstract

For the purpose of development of adsorbents for the extraction of uranium from sea water, titanium based composite hydrous oxides were synthesized and their uranium adsorption capacities were investigated. They are composite hydrous oxides of Ti(IV)-Al(III), Ti(IV)-Fe(III), Ti(IV)-Ce(III), Ti(IV)-Cr(III), Ti(IV)-La(III), Ti(IV)-Si(IV), Ti(IV)-Zr(IV) and Ti(IV)-Sn(IV), prepared as precipitation products by addition of sodium hydroxide solution to the mixed solution of titanium tetrachloride and acidic solution of other metal.Adsorption experiments were carried by batch method using sea water in which slight amount of uranyl chloride was added. The initial uranium concentration was 10.1μg/l. The composite hydrous Ti(IV)-Fe(III) oxide was found to give the largest uranium adsorption capacity among the composite hydrous oxides and its uranium adsorption capacity per gram of titanium in adsorbent was about twice larger than that of hydrous Ti(IV) oxide alone.Uranium adsorption capacity of composite hydrous Ti(IV)-Al(III) oxide increases with the temperature of precipitation process.The composite hydrous Ti(IV)-Fe(III) oxide shows its maximum uranium adsorption capacity when it was prepared from pH5 and 7 at 70°C. It was found that the composite adsorbent, hydrous Ti(IV)-Fe(III) oxide, had its large uranium adsorption capacity when its mean pore radius was between 20 and 33Å, and its specific surface area was between 250 and 325mm2/g.