Studies on the solvent extraction of rare earths from nitrate media with a combination of di‐(2‐ethylhexyl)phosphoric acid and sec‐octylphenoxyacetic acid

Abstract

BACKGROUND: Di-(2-ethylhexyl)phosphoric acid (D2EHPA, H 2 A 2 ) has been used extensively in hydrometallurgy for the extraction of rare earths, but it has some limitations. Synergistic extraction has attracted much attention because of its enhanced extractabilities and selectivities. In the present study, sec-octylphenoxyacetic acid (CA12, H 2 B 2 ) was added into D2EHPA systems for the extraction and separation of rare earths. The extraction mechanism of lanthanum with the mixtures and the separation of lanthanoids and yttrium were investigated.

Effective solvent extraction of La, Ce and Pr from hydrochloric acid with a novel extractant N,N-dihexyloxamic acid

“…CA12 is considered an effective carboxylic acid extractant for REs extraction and has been studied extensively in recent years, so we compare HA with CA12 in Fig. .…”

“…It has been reported that the extraction pH value for REs with sec‐nonylphenoxyacetic acid (CA100) can be lowered to 2.5 in heptane . In addition, several types of synergistic systems, such as 2‐ethylhexylphosphonic acid mono‐(2‐ethylhexyl) ester/CA100, bis(2,4,4‐trimethylpentyl)phosphinic acid/CA100 and di‐(2‐ethylhexyl)phosphoric acid/ sec‐octylphenoxyacetic acid (CA12), have also been used to improve the extraction ability and selectivity of phenoxyacetic acid …”

Binary extraction of lanthanides (III) nitrates with carboxylates and dialkylphosphates of secondary and tertiary amines

“…The case of excess amine nitrate in the organic phase compared with the stoichiometry of an inorganic salt extraction and salting-out the metal (excluding solvation process and at x e x s D high extractant excess) can be described by Eqs. (7) and (8) as follows:…”

“…This process is usually carried out using countercurrent extraction cascades containing several dozen successive extractors. Organophosphorus extractants, such as TBP, di-(2ethylhexyl) phosphoric acid (D2EHPA), dialkylphosphinic, dialkyldithio phosphinic and carboxylic acids are mainly used to produce REM [3][4][5][6][7][8].…”

Solvent extraction studies of Sm(III) from nitrate medium and separation factors of rare earth elements with mixtures of sec‐octylphenoxyacetic acid and 1,10‐phenthroline

“…A variety of extractants have been used in synergistic extraction including: acidic organophosphorus extractants,3–11 neutral organophosphorus extractants,4, 5, 12–14 carboxylic acids,6, 8–12 amines,15 β‐diketones,13, 14, 16–27 crown ethers,28 calix[4]arenes,29 and neutral nitrogen donors 5, 7, 15–27. For example, Luo et al 3 have studied the synergistic extraction of cerium from sulfuric acid using mixtures of di‐(2‐ethylhexyl) phosphoric (D2EHPA) and 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester (HEHEHP) and have determined the synergistic enhancement coefficients, the nature of the extracted complex, and the equilibrium constants.…”