Yao Liu, Junli Wang, Yuhang Le, Hui Wang, Wentao Wang, Baole Li, Taihong Yan
Department of Radiochemistry, China Institute of Atomic Energy P. O. Box 275-26 Beijing 102413 P.R. China
RSC Adv. 2024 Jan 2;14(1):560-567. doi: 10.1039/d3ra07418h.
In this study, three phenylpyridine diamide ligands, namely, 2,2'-((pyridine-2,6-diylbis(3,1-phenylene))bis(oxy))bis(,-diethylacetamide) (PPEA, L1), 2,2'-((pyridine-2,6-diylbis(3,1-phenylene))bis(oxy))bis(-ethyl--phenylacetamide) (PEPA, L2), and 2,2'-(((4-phenylpyridine-2,6-diyl)bis(3,1-phenylene))bis(oxy))bis(,-dioctylacetamide) (PPOA, L3), were synthesized and explored for the solvent extraction of Pu(iv) in a HNO medium using 1-(trifluoromethyl)-3-nitrobenzene as the diluent. The effects of HNO concentration, extractant concentration, and temperature on the Pu(iv) extraction efficiency were studied. All three extractants displayed high selectivity for Pu(iv) over other metals such as U(vi), Np(v), Am(iii), and various fission elements. At 3 M HNO, the distribution ratio for Pu(iv) reached 27.18, in contrast to 1.11, 0.3, and 0.03 for U(vi), Np(v), Am(iii), respectively. Slope analysis and UV titration revealed the formation of 1 : 1 Pu(NO)/ligand complexes during extraction. The extraction reactions had negative Gibbs free energies, indicating the spontaneous nature of Pu(iv) extraction at room temperature. Furthermore, the extractants demonstrated good stripping ability and reusability, and their radiolytic stability was reasonable up to an absorbed dose of 100 kGy, underscoring their potential for practical applications. Overall, this study broadens our understanding of actinide-diamide ligand coordination and actinide chemistry during coordination, paving the way for the design and synthesis of new extractants.
在本研究中，合成了三种苯基吡啶二酰胺配体，即2,2'-((吡啶-2,6-二基双(3,1-亚苯基))双(氧基))双(,-二乙基乙酰胺)(PPEA，L1)、2,2'-((吡啶-2,6-二基双(3,1-亚苯基))双(氧基))双(-乙基--苯基乙酰胺)(PEPA，L2)和2,2'-(((4-苯基吡啶-2,6-二基)双(3,1-亚苯基))双(氧基))双(,-二辛基乙酰胺)(PPOA，L3)，并以1-(三氟甲基)-3-硝基苯为稀释剂，研究了它们在硝酸介质中对Pu(iv)的溶剂萃取性能。研究了硝酸浓度、萃取剂浓度和温度对Pu(iv)萃取效率的影响。所有三种萃取剂对Pu(iv)的选择性均高于其他金属，如U(vi)、Np(v)、Am(iii)和各种裂变元素。在3 M硝酸中，Pu(iv)的分配比达到27.18，而U(vi)、Np(v)、Am(iii)的分配比分别为1.11、0.3和0.03。斜率分析和紫外滴定表明，萃取过程中形成了1∶1的Pu(NO)/配体配合物。萃取反应的吉布斯自由能为负，表明室温下Pu(iv)的萃取是自发的。此外，萃取剂表现出良好的反萃能力和可重复使用性，在吸收剂量达100 kGy时，其辐射稳定性良好，这突出了它们在实际应用中的潜力。总的来说，本研究拓宽了我们对锕系元素-二酰胺配体配位以及配位过程中锕系元素化学的理解，为新型萃取剂的设计与合成铺平了道路。
