Diglycolamide with long C-chains combined with ether bonds for high loading of Am(III) and Eu(III): Extraction, aggregation, and third-phase formation studies

[Display omitted] •The introduction of ether bonds can significantly improve the loading capacity of DGA ligand.•The introduction of ether bonds has no adverse effect on the distribution ratio of Am3+ and Eu3+.•The generation of bulky rod-like reverse micelle aggregates for TOOEDGA is more difficult than that for TODGA.•TOOEDGA can tolerate a wider concentration range of HNO3 during the solvent extraction process. Diglycolamide (DGA) extractants, especially TODGA (N,N,N′,N′‐tetraoctyl diglycolamide), show significant potential in high-level liquid waste treatment. However, their limited loading capacity for trivalent lanthanides (Lns) and actinides (Ans) often leads to detrimental emulsification or third phase formation, hindering their practical applicability. Herein, TOOEDGA (N,N,N’,N’-tetra(2-(octyloxy)ethyl)diglycolamide), a new DGA extractant with long C-chains combined with ether bonds, exhibits superior extraction performance towards Am3+ and Eu3+ in HNO3 solution compared to TODGA. The factors influencing the formation of a third phase during the extraction process were investigated. It has been shown that TOOEDGA has a greater loading capacity for Lns3+ and can tolerate a wider concentration range of HNO3. Additionally, the aggregation behavior of DGAs in n-dodecane was also studied using dynamic light scattering and small-angle X-ray scattering, revealing that the reverse micelles formed by TOOEDGA are more stable than those formed by TODGA. Moreover, under similar conditions, TOOEDGA molecules do not aggregate further to generate rod-like reverse micelle aggregates like those observed with TODGA, which is beneficial to inhibit the formation of the third phase. Consequently, our results suggest that TOOEDGA holds great promise as an alternative DGA extractant for practical industrial applications.