Study on the aqueous solution behavior and extraction mechanism of Nd(iii) in the presence of the complexing agent lactic acid with di-(2-ethylhexyl) phosphoric acid

Abstract

The aqueous solution behavior and extraction mechanism of single Nd(III) from a chloride medium with di-(2-ethylhexyl) phosphoric acid (D2EHPA, H₂A₂) in the presence of the complexing agent lactic acid (HLac) have been reported. The analyses by FT-IR and UV of the aqueous solution indicate that there is a coordination mechanism between Nd³⁺ and Lac⁻ in the form of the carboxyl oxygen bridge bidentate ligand. A cation extraction mechanism has been studied using the method of slope analysis and saturation loading capacities, and also confirmed by FT-IR and NMR. The equilibrium constants and thermodynamic functions have been calculated. The separation factors of La/Ce, Ce/Pr and Pr/Nd are 3.24, 2.04 and 1.58, indicating that this system is beneficial for separating light rare earths. The results could provide some reference value for complexing extraction systems.