The separation of zinc and copper ions from sulfuric acid solutions by an
emulsion liquid membrane (ELM), using di-(2-ethylhexyl) phosphoric acid
(D2EHPA) as a carrier, has been investigated. The batch extraction of zinc and
copper was carried out while varying a selection of experimental conditions, i.e.,
stirring speed, treatment ratio, concentrations of metal ions in the feed phase,
carrier and Span 80 concentration in the membrane, and internal phase concentration.
The results obtained demonstrate the effectiveness of D2EHPA as a carrier
for the separation of zinc and copper from sulfuric acid media using an ELM.
An increase of the D2EHPA concentration beyond 2 vol.-% does not result in the
improved extraction of zinc because the viscosities of the membrane and emulsion
have a trend to increase for higher carrier concentrations. It was found that
the extraction rate of copper was affected by the carrier concentration in the
liquid membrane and by the pH and metal content in the external phase. A
3 vol.-% concentration of surfactant in the organic phase was required to stabilize
the emulsion. The number of stages required for the extraction of zinc and copper
by an ELM was determined from McCabe-Thiele plots. |
