CeRES Process−Separation of Cerium from Lanthanum by Redox Extraction and Stripping

Effective methods for rare earth separation remain an important challenge that could benefit from new approaches. In this study, we demonstrate that for La/Ce separation, an in situ electrochemical Redox process in combination with Extraction and Stripping would provide very efficient separation of these elements in a single extraction step (CeRES). By combining in situ electrochemical oxidation and simultaneous solvent extraction with a stripping process involving electrochemical reduction, separation of Ce3+ from La3+ is achieved. Here, Ce3+ is electrochemically oxidized to Ce4+ and removed from the aqueous phase by solvent extraction with 100 mM D2EHPA in n-octane. To recover Ce4+ from the loaded organic phase, in situ electrochemical reduction of Ce4+ to Ce3+ is employed. Thus, extraction and stripping by the redox state change triggered only by electrochemistry are achieved for the first time by using a shared organic phase. The approach was verified in a rapid prototype cell using the additive manufacturing technique, which enables a high Ce extraction of 85% and its recovery with nearly 100% purity in a single extraction step without the use of additional reagents.