Extraction and separation of rare earths from chloride medium with mixtures of 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester and sec-nonylphenoxy acetic acid

BACKGROUND: 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEHEHP, H(2)A(2)) has been applied extensively to the extraction of rare earths. However, there are some limitations to its further utilization and the synergistic extraction of rare earths with mixtures of HEHEHP and another extractant has attracted much attention. Organic carboxylic acids are also a type of extractant employed for the extraction of rare earths, e.g. naphthenic acid has been widely used to separate yttrium from rare earths. Compared with naphthenic acid, sec-nonylphenoxy acetic acid (CA100, H2B2) has many advantages such as stable composition, low solubility, and strong acidity in the aqueous phase. In the present study, the extraction of rare earths with mixtures of HEHEHP and CA100 has been investigated. The separation of the rare earth elements is also studied.