Adsorption study of U and Th by N,O-hybrid donor ligand-immobilized hydrogels
Adsorption study of U and Th by N,O-hybrid donor ligand-immobilized hydrogels
复制标题
DOI：
10.1080/01496395.2019.1575881
复制
发表时间：
2019-02
影响因子：
2.8
通讯作者：
M. Nakase;T. Yamamura;K. Shirasaki;M. Nagai;K. Takeshita
中科院分区：
文献类型：
--
作者：
M. Nakase;T. Yamamura;K. Shirasaki;M. Nagai;K. Takeshita
摘要钍燃料循环由于其潜在的优点再次引起人们的关注，但与铀燃料循环相比，相关的后端技术仍然不够成熟。在钍氧化物乏燃料的化学后处理中，由于233 U的伴生产物232 U产生的208 Tl的强辐射，需要将UO 22+与Th 4+有效分离，并且在后处理过程中预计会有相当高的剂量率。因此，将凝胶/液萃取技术应用于U/Th分离，通过C-C键将配体化学引入到水凝胶中，可以最大限度地减少配体的溶出，并有望提高配体的抗辐射能力。合成了一些具有可聚合官能团的N，0-杂化供体配体-用于凝胶吸附剂合成的双（二-N-烯丙基-N-甲苯基）菲二酰胺（Allyl-Tol-PTDA）和N，N，N '，N'-四烯丙基吡啶-2，6-二甲胺（Tet-Allyl-PDA）和N，N，N '，N'-四己基吡啶-2，6-二甲胺（Tet-Hex-PDA）-用于溶剂萃取，因为Allyl-Tol-PTDA在正十二烷中具有低溶解度。然后将Allyl-Tol-PDA和Tet-Allyl-PDA分别与N-异丙基丙烯酰胺（NIPA）和N，N ′-亚甲基双丙烯酰胺（BIS）进行聚合反应，得到温敏性水凝胶PTDA-凝胶和PDA-凝胶。比较了Allyl-Tol-PTDA和Tet-Hex-PDA代替Allyl-Tol-PDA的一般萃取行为以及PTDA-凝胶和PDA-凝胶对UO 22+和Th 4+的吸附行为。因此，确定了溶剂萃取和凝胶吸附之间的不同萃取/吸附行为。的PTDA凝胶显示没有强烈的依赖于酸度和温度与UO 22+，但Th 4+显示了一个局部最大值与不同的酸度。相比之下，PDA-凝胶表现出温度依赖性：UO 22+在较高温度下吸附更多，Th 4+在较低温度下吸附更多。因此，（i）PTDA-凝胶在较高温度和酸度下，和（ii）PDA-凝胶在较高温度和较低酸度下，U/Th分离是可能的。
ABSTRACT The thorium (Th) fuel cycle is attracting attention again because of its potential merits over the uranium (U) fuel cycle, but the associated back-end technology remains insufficiently mature compared with that of the U fuel cycle. In the chemical reprocessing of spent Th oxide fuels, effective separation of UO22+ from Th4+ is required and a quite high dose rate is expected in reprocessing because of the strong radiation by 208Tl generated from 232U, an associated product of 233U. Therefore, gel/liquid extraction was applied to U/Th separation．Introducing ligands chemically into the hydrogels (via the C–C bonds) can minimize ligand leaching, and the ligands are expected to be more resistant to radiation. Some of the N,O-hybrid donor ligands that have polymerizable functional groups – Bis(di-N-allyl-N-tollyl) phenanthlorine diamide (Allyl-Tol-PTDA) and N,N,N’,N’-tetraallylpyridine-2,6-dicarboxamine (Tet-Allyl-PDA) for gel adsorbent synthesis and N,N,N’,N’-tetrahexylpyridine-2,6-dicarboxamine (Tet-Hex-PDA) – were synthesized for solvent extraction because Allyl-Tol-PTDA has low solubility in n-dodecane. Allyl-Tol-PDA and Tet-Allyl-PDA were then polymerized with N-isopropylacrylamide (NIPA) and N,N’-methylenbisacrylamide (BIS) to give thermosensitive hydrogels, namely PTDA-gel and PDA-gel. The general extraction behaviors of Allyl-Tol-PTDA and Tet-Hex-PDA instead of Allyl-Tol-PDA and the adsorption behaviors of PTDA-gel and PDA-gel were compared with those of UO22+ and Th4+ in HNO3. Consequently, differing extraction/adsorption behavior between solvent extraction and gel adsorption was determined. The PTDA gel showed no strong dependency on acidity and temperature with UO22+, but Th4+ showed a local maximum with varying acidity. By contrast, the PDA-gel showed temperature dependency: UO22+ adsorbed more at higher temperature and Th4+ adsorbed more at lower temperature. Therefore, U/Th separation is possible with (i) PTDA-gel at higher temperature and acidity, and (ii) PDA-gel at higher temperature and lower acidity.