Study on the extraction behavior of Nd(iii) in nitric acid medium by novel asymmetric alkyl diglycolamide extractants with different structures†

Abstract

The rare earth element neodymium plays an indispensable role in modern industry, and the development of efficient and environmentally friendly extraction technology is crucial to meet the growing demands. As new extractants, diglycolamides with cyclohexyl and N-alkyl substituents can affect the extraction ability by adjusting the interaction between the extractant and the extract. In this paper, three extractants N,N′-diethyl-N,N′-dicyclohexyl diglycolamide (DEDCHDGA), N,N′-dipropyl-N,N′-dicyclohexyl diglycolamide (DPDCHDGA), and N,N′-dibutyl-N,N′-dicyclohexyl diglycolamide (DBDCHDGA), were designed and synthesized. The effects of time, nitric acid acidity, and diluent on the extraction performance of Nd(III) were studied. The extraction ability of the DGAs in 1,2-dichloroethane towards Nd(III) followed the order: DEDCHDGA > DPDCHDGA > DBDCHDGA. The extraction mechanism was elucidated through slope analysis, FT-IR, and XPS analysis. The structure–activity relationship between the N-alkyl substituent structure and Nd(III) extraction ability was also discussed. This study not only provides a new approach for neodymium extraction but also offers a valuable reference for the development of environmentally friendly extractants.