Liquid-liquid Extraction of U(Ⅵ) and Pu(Ⅳ) with 2,2′-((4-Ethoxy-1,2-phenylene) bis (oxy)) bis (N,N-bis(2-ethylhexyl)acetamide)

To develop a highly selective extractant for Pu(Ⅳ), 2,2′-((4-ethoxy-1,2-phenylene)bis(oxy)) bis (N,N-bis(2-ethylhexyl)acetamide), short for 4-EthoxyBenzoDODA, has been evaluated as a novel extractant in n-dodecane diluent for the extraction of U(Ⅵ) and Pu(Ⅳ). The effect of contact time of two phases, HNO₃ concentration and extractant concentration on the distribution ratios of U(Ⅵ) and Pu(Ⅳ) was investigated. Acid uptake studies suggested that 4-EthoxyBenzoDODA (KH=0.14) was less basic as compared to BenzoDODA (KH=0.44), making it more conducive to selectively extract Pu(Ⅳ) with stronger ionic potential. Extraction experiments showed that the maximum of SFPu/U, SFPu/Eu were 6.9, 223 respectively. Slope analysis indicated extraction of 1∶1 (ML) species with U(Ⅵ) and mixed 1∶1 (ML) and 1∶2 (ML2) species with Pu(Ⅳ) at 4.0 mol/L HNO₃ 98% of Pu in the loaded organic phase can be stripped to the aqueous phase using reductive stripping agent such as hydrazine nitrate and hydroxylamine nitrate. The results showed that the 4-EthoxyBenzoDODA exhibited good selectivity toward Pu.