Solvent extraction of bismuth with 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester and 2,2′-bipyridyl

In the present work, the solvent extraction of bismuth with mixtures of acidic phosphorus extractants, di(2-ethylhexyl) phosphoric acid (D2EHPA) and 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEHEHP), with some other extractants was investigated including sec-octylphenoxyacetic acid (CA12), sec-nonylphenoxy acetic acid (CA100), 8-hydroxyquinoline (HQ), and 2,2′-bipyridyl (bipy). The extraction effects from nitric acid medium were studied in detail. Results showed that all other mixing systems except HEHEHP + bipy did not have synergistic effects on bismuth. The methods of slope and constant mole were employed to study the extraction of bismuth in HEHEHP + bipy system. Thermodynamic functions and stripping behaviors were also investigated.

► Solvent extraction of bismuth was investigated with mixtures based on acidic phosphorus extractants.
► Mixtures of 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester and 2,2′-bipyridyl had synergistic effects on bismuth.
► The extracted complex, equilibrium constants, and thermodynamic functions were determined for the extraction of bismuth.