A process for recovery of zinc from acid solution with di(2-ethyl hexyl
phosphoric acid) (D2EHPA) dissolved in iso-dodecane was carried out at 208C in a
countercurrent tubular membrane extractor using a hollow fiber as solid support.
Experiments were performed at different aqueous metal concentrations (0.1–
1.0 g/L), pH 0.1–2.1, and D2EHPA concentrations (2–8 v%). It was found that
both the flux of metal and the extraction extent was highly influenced by the extractant
concentration and the pH of the feed solution. Overall mass transfer coefficients were
determined and related to the tube side, the membrane, and the shell side mass transfer
by varying the aqueous flow rate (0.38–0.80 L/min) and organic flow rate (0.22–
0.57 L/min) in countercurrent flow. The overall mass transfer coefficient for zinc
extraction ranged from 6.2
1026 m/s to 25.3
1026 m/s. It was concluded that
extraction kinetics were a major contributor to the overall resistance to mass transfer.