Sorption behavior of Np(V) on illite, shale and MX-80 in high ionic strength solutions

高イオン強度水溶液中でのイライト, 頁岩, MX-80ベントナイトへのNp(V)の吸着

長崎 晋也*; 斉藤 拓巳; Yang, T.*

Nagasaki, Shinya*; Saito, Takumi; Yang, T.*

高塩濃度(6.0Mのイオン強度を有する模擬塩水、および、異なるNa/Ca比、イオン強度を有するNa-Ca-Cl溶液)、酸化的な雰囲気におけるイライト, 頁岩, ベントナイトへのNp(V)の吸着をバッチ法にて評価した。全ての固相に対して、吸着の分配比(Kd)はpHc、Na/Ca比の増加とともに上昇した。イライトと頁岩へのKdはイオン強度0.14.6Mの範囲でイオン強度に依存せず、また、ベントナイトへのKdは1.0M以上でイオン強度に依存しなかった。

Sorption of Np(V) on illite, shale and MX-80 under oxidizing conditions were first studied in two types of high ionic strength solutions: (1) a reference brine solution (SR-270-PW) with an ionic strength (I) of 6.0 M, and (2) Na-Ca-Cl solutions (with different Na/Ca molar ratios and different ionic strengths, up to a maximum of 4.6 M). The effects of pHc, Na/Ca ratio, and ionic strength on sorption in Na-Ca-Cl solutions were investigated. The Kd values increased with increasing pHc and Na/Ca ratio for all sorbents studied. The Kd values on illite and shale were independent of the ionic strength over the range 0.10-4.6 M, and the Kd value on MX-80 was independent of ionic strength greater than 1.0 M. The Kd values and the sorption isotherms in both SR-270-PW and Na-Ca-Cl solutions were also studied.