ABSTRACT
A binary mixture of two acidic organophosphorus extractants, such as 2-ethylhexylphosphonic mono-2-ethylhexyl ester (HEHEHP) and di-2-ethylhexyl phosphoric acid (D2EHPA), is widely employed for the extraction and separation of light rare earths (LRE) from chloride medium, which displayed pronounced synergistic effect. The water-soluble complexing agent lactic acid (HLac) was added to the aqueous phase to optimize the extraction process. The interactions of LRE with water, HLac and extractants in each phase have been deeply studied to elucidate the extraction behavior. Based on the experiment results, the chemical reactions that occur during extraction are studied in detail, the cation exchange (P-OH bands) and coordination interaction (P = O bands) contribute to LRE extraction were verified.