Separation of Zinc by a Non-dispersion Solvent Extraction Process in a Hollow Fiber Contactor.

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 20°C in a countercurrent tubular membrane extractor using a hollow fiber as solid support. Experiments were performed at different aqueous metal concentrations (0.1-l.0g/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 × 10-6 m/s to 25.3 × 10-6 m/s. It was concluded that extraction kinetics were a major contributor to the overall resistance to mass transfer. [ABSTRACT FROM AUTHOR]