Effect of complexing agent lactic acid on the extraction and separation of Pr(III)/Ce(III) with di-(2-ethylhexyl) phosphoric acid

The extraction of rare earths (REs) in a saponated system with di-(2-ethylhexyl) phosphoric acid (P204) as an extractant will produce a large amount of waste water, which contains NH4+, Ca2+ and Na+, and will seriously pollute the environment. The paper aims to develop a new system to eliminate the phenomena. The separation of Pr(III)/Ce(III) using P204 is investigated by adding a complexing agent lactic acid (LA) into the aqueous phase. The separation factor and extraction capacity are as high as 2.02 and 32.67 g/L with the increase of the lactic add concentration, respectively, and both higher than those without the complexing agent. The cation-exchange mechanism is clarified by IR spectra and H-1 NMR. The experimental results suggest that the complexing extraction method could be regarded as an effective strategy for separating REs. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.