The effect of di-iso-amyl phosphate on the uranium extraction behavior and mechanisms of tri-iso-amyl phosphate: A new insight via experimental and theoretical approaches

• Published in: Journal of molecular liquids Vol. 409; p. 125471
• Main Authors: Shi, Shilong, Qin, Yilin, Zhang, Runyu, Xiao, Chuyan, Li, Feize, Lan, Tu, Yang, Jijun, Yang, Yuanyou, Liao, Jiali, Liu, Ning
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2024
• Subjects: Di-iso-amyl phosphate (HDiAP); Molecular dynamics simulations; TiAP/n-dodecane system; U(VI) extraction mechanisms; Molecular dynamics simulations; Di-iso-amyl phosphate (HDiAP); TiAP/n-dodecane system; U(VI) extraction mechanisms
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2024.125471

•First attempt to explore the U extraction mechanisms of TiAP coexisted with HDiAP.•UO2(NO3)2(Ligand)2 and UO2(DiAP)2(Ligand)2 are the main extracted U species.•Electrostatic attraction dominates the interaction between U and extractants.•The HDiAP can enhance the U extraction but resist the U stripping. Exploring the extraction behavior and mechanism of extractants in the presence of the radiolysis products was helpful to the design and subsequent utilization of those potential spent fuel extractants. In this work, Di-iso-amyl phosphate (HDiAP), a major acidic radiolysis product of Tri-iso-amyl phosphate (TiAP), was employed to study its effects on uranium (U(VI)) extraction behavior and mechanisms of 36 % TiAP/n-Dodecane (36 % TiAP/nDD) system by using extraction experiments, density functional theory calculations (DFT) and molecular dynamic simulations (MD). The results demonstrated that the presence of HDiAP improved U(VI) extraction but inhibited U(VI) stripping. The extracted U(VI) species analysis identified the UO2(NO3)2(L)2 and UO2(DiAP)2(L)2 (L = TiAP/HDiAP) as the primary extracted U(VI) complexes. The DFT calculations revealed a higher tendency and a more exothermic process for the formation of U(VI)–HDiAP complexes than U(VI)–TiAP complexes. The MD simulations showed that HDiAP will be closer to the interface than TiAP, which is beneficial to its interaction with U(VI). The electrostatic force dominated the interaction between U(VI) and ligands, and its strength follows the order of U–DiAP− > U–TiAP > U–HDiAP. The presence of DiAP− was the main reason that impeded the U(VI) stripping. This work reveals the U(VI) extraction behavior and mechanism of the 36 % TiAP/nDD system in the presence of HDiAP, providing new insights into the effects of radiolysis products on the U(VI) extraction by potential fuel reprocessing extractants.