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Simonnet, M.; 宮崎 有史; 鈴木 伸一; 矢板 毅
Progress in Nuclear Science and Technology (Internet), 5, p.66 - 69, 2018/11
Cs is a dangerous fission product because of its half-life of 30 years and its high production yield. After several years, it becomes one of the main heat generator in nuclear waste; it would thus be beneficial to remove it before deep repository storage. Cesium also shows high mobility in the environment, thus being one of the most dangerous material released in accidental situation. Because the chemistry of cesium is close to these of sodium and potassium, found in great amount in water, cesium recovery requires very high separation factor towards these elements. Calix-crown-ether compounds show high extraction of Cs, and Na separation factor up to million (up to ten thousands for K), depending on experimental conditions and extractant structure. This study attempts to qualitatively and, when possible, quantitatively describe these dependencies. Focus has been made on HNO
concentration (0.01M to 6M), solvent nature, and extractant structure, based on the already well-documented di-octyloxy-calix[4]mono-crown-6.
,-dialkylamides-nitric acid systems筒井 菜緒; 伴 康俊; 袴塚 保之; ト部 峻一; 松村 達郎
Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1153 - 1157, 2015/09
,-ジアルキルアミドは使用済燃料の湿式再処理に用いられているリン酸トリブチルの代替抽出剤として有望であるが、有機相と水相の二相分離の定量的評価はまだなされていない。本研究では、濁度測定を用いてその定量的評価を行った。ドデカンで希釈した,-ジ(2-エチルヘキシル)-2,2-ジメチルプロパンアミド(DEHDMPA)と硝酸ウラニルを含む硝酸溶液をよく撹拌し、濁度及びウランの分配比の測定を行った。DEHDMPA、ウラン及び硝酸濃度の増加に伴い有機相中の濁度は増加した。濁度は時間の経過に伴い減少したが、ウランの分配比の変化はわずかであり、観測された濁度はウラン分配比に大きな影響を与えないことが示された。これらの結果は、二相分離の観点からDEHDMPAは硝酸中のウラン抽出剤として機能し得ること、及び濁度が抽出挙動評価の指針の一つになり得ることを示している。
米澤 仲四郎; 大西 寛
Journal of Radioanalytical Chemistry, 36, p.133 - 144, 1977/00
チオシアン酸塩と第4級アンモニウム塩(ゼフィラミン)を用いる液液抽出法と抽出クロマトグラフィーによるモリブデンからタングステンの分離法を確立した。タングステンはタングステン(V)-チオシアン酸錯体とゼフィラミン陽イオンとのイオン会合体としてクロロホルムに抽出され、また、ゼフィラミンをコーティングしたテフロンパウダーを固定相としたカラムに保持された。しかし、モリブデン(III)はクロロホルムに抽出されず、カラムにも保持されなかった。抽出クロマトグラフィーをモリブデン中の微量のタングステンの中性子放射化分析法による定量法に応用して良い結果を得た。
Simonnet, M.; 宮崎 有史; 鈴木 伸一; 矢板 毅
no journal, ,
Study of cesium separation from acidic and alkaline waste has been conducted since the 90's. Calix[4]-crown-6-ethers can selectively extract cesium with higher distribution ratios than crown-ethers or dicarbollides. Several authors focused on dioctyloxycalix[4]crown-6 (DOC[4]C6), also tested on real waste in dodecane/TBP mixture. 99.9% of cesium was extracted but TBP, mandatory to solvate the calix-crown in dodecane, lowered the selectivity. The distribution ratio DCs remained also rather low. This study focuses on extractant and solvent effects. Because DOC[4]C6 showed good results and is well-documented, extractants were synthesized by modifying its structure: change of the alkoxy chain length led to didodecyloxycalix[4]crown-6 (DDC[4]C6) and diethylhexyloxycalix[4]crown-6 (DEHC[4]C6); change on the crown-ether led to dioctyloxycalix[4]benzo-crown-6 (DOC[4]BC6) and dioctyloxycalix[4]di-benzo-crown-6 (DOC[4]DBC6). Studies on DOC[4]BC6 and DOC[4]DBC6 can be found in literature. Based on literature study, pure solvents: n-octanol (n=1,2,3), methylcyclohexanone (MCHK), 2-nonanone; and mixtures of 1-octanol + 10% modifiers (nitrophenyloctylether (NPOE), TBP) have been tested.
Simonnet, M.; 宮崎 有史*; 鈴木 伸一; 小林 徹; 土井 玲祐; 塩飽 秀啓; 矢板 毅
no journal, ,
Cs is one of the highest heat generators in nuclear waste. Removing it prior to deep geological disposal can thus help reducing the necessary volumes and costs of the final repository. This isotope is also one of the main contaminants that was released during the Fukushima Nuclear Power Plant accident. Liquid-liquid extraction can be a suitable method for decontamination. In this study, seven different extractants from the calix-mono-crown-arene family have been compared as respect to distribution ratio, separation factors and closer atoms distances to cesium. Distribution ratios also strongly depend on diluent nature. EXAFS study was thus conducted on two extractants in chloroform and 2-nonanone to investigate whether diluent nature can impact the cesium-ligand complex itself. Spectra showed that whilst no difference was observed on the first coordination shell, diluent nature impacted the second shell. However, oxygen positions remained similar in both diluents, leading to a probable change in benzene 
-electron interaction with cesium.
