736. テクネチウムイオンの水酸化鉄による共沈反応
1982 年 24 巻 2 号 p. 150-154
詳細
1982 年 24 巻 2 号 p. 150-154
Coprecipitation of radioactive technetium with hydroxides has been studied for the purpose of the management of the high level waste from the nuclear fuel reprocessing. Pertechnetate ion was reduced to Tc(IV) by ferrous ion (Fe2+), and then coprecipitated with Fe(OH)2 (I) as TcO2. The pH of nitric acid solution containing TcO4- was adjusted to 1.0 with NaOH, and TcO2 was precipitated by reducing coprecipitants i.e. (I), Fe(OH)2-Zr(OH)4 (II), Fe(OH)2-Si(OH)4 (III) and Fe(OH)2-Zr(OH)4-Si(OH)4 (IV). Pertechnetate ion quantitatively coprecipitates under the conditions: Fe2+>3.6×10-3M; pH=6-12 for (I), pH=4.2-12 for (II), pH=8-12 for (III) and pH=6-12 for (IV). The presence of excess Fe2+ prevents the dissolution owing to air-oxidation of TcO2 coprecipitated. Pertechnetate ion can be also removed from the waste solution by boththe ferrite precipitation method and the iron powder precipitation method.
