Separation of zinc from lean sphalerite leached liquor in nitrate medium with D2EHPA using supported liquid membrane

Abstract

Separation of zinc and lead from an aqueous nitrate medium using supported liquid membrane with di(2-ethylhexyl)phosphoric acid (D2EHPA) as mobile carrier was studied. Celgard-2500, a microporous polypropylene film, was used as the solid support for the liquid membrane with a plate and frame type of cell used for the experiments. The effects of different parameters such as pH of feed solution (1–3·5), D2EHPA concentration in the membrane phase (10–100 mol m⁻³), acid concentration in strip solution and flowrate of the aqueous solution on separation of lead and zinc were studied. It was observed that zinc flux across the membrane increased with pH of the feed solution up to 3·0 and thereafter decreased while zinc flux increased with the D2EHPA concentration in the membrane phase up to 75 mol m⁻³ and thereafter decreased. The flowrate of 100 mL min⁻¹ was sufficient to reduce the resistances due to the aqueous boundary layer while 950 mol m⁻³ H₂SO₄ was found sufficient to strip the metals from the membrane phase in the strip phase. Under the study conditions, the copermeation of lead with zinc was observed to be negligible.