U(VI) back-extraction trials for measurement of U(VI) mass transfer efficiency in single stage centrifugal contactor

None

佐野 雄一   ; 柴田 淳広  ; 小泉 務; 小山 智造; Fox, D.*; Carrott, M.*; Taylor, R.*

Sano, Yuichi; Shibata, Atsuhiro; Koizumi, Tsutomu; Koyama, Tomozo; Fox, D.*; Carrott, M.*; Taylor, R.*

単段小型遠心抽出器を用いたU(VI)逆抽出試験を実施した。遠心抽出器を用いた逆抽出系におけるU物質移動効率の供給流量、ロータ回転数及び温度依存性を詳細に評価した。得られた結果は次のとおりである。(1) 今回の試験条件下において、遠心抽出器内における水相及び有機相の挙動は完全混合槽型反応器モデルによって表すことができる。(2) 今回の試験条件下において観測されたロータ回転数の上昇に伴う物質移動効率の低下は、遠心抽出器内のフローパターンの変化に起因するものと推測される。(3) 温度依存性評価より、低ロータ回転数においてはU(VI)逆抽出反応が拡散律速であると考えられるのに対し、高ロータ回転数においては化学反応の寄与も大きくなることが示唆された。

Based on the U(VI) back-extraction experiments with the miniaturized single stage centrifugal contactor, effects of the total flowrate, the rotor speed and the temperature on the U(VI) mass transfer efficiency were discussed. The relationship between the U(VI) mass transfer efficiency and the residence time suggested that the U(VI) back-extraction system with the centrifugal contactor could be treated as a perfectly stirred continuous reactor. It is considered that the variations of the mass transfer efficiency were caused by the flow pattern change from the laminar flow to the turbulent flow with increasing of the rotor speed in the centrifugal contactor. In the U(VI) back-extraction under the high rotor speed condition, no significant temperature dependence of the apparent overall transform coefficient was observed. In the U(VI) back-extraction under the low rotor speed condition, temperature dependence of the apparent overall transform coefficient seemed to be larger than under the high rotor speed condition, and it suggested a chemical-step contribution in this system. Such a difference of the temperature dependence of the apparent overall transform coefficient between these experiments might be caused by the change of solvent extraction environments in the centrifugal contactor with the variation of the rotor speed.