The separation of praseodymium from the solution of mixed rare earths via a lab-scale hollow fiber supported liquid membrane (HFSLM) was examined. The studied parameters were the pH of feed solution (the solution of mixed rare earths), type of the extractant or carrier (Cyanex 301, Bis(2,4,4-trimethylpentyl) phosphinic acid or Cyanex 272 and Aliquat 336) in kerosene, concentration of the extractant and stripping solution, flow rates of feed and stripping solutions and the separation time through the hollow fiber module. Hydrochloric acid solution was used as the stripping solution Cyanex 272 was found to be the most suitable extractant in extraction and stripping of praseodymium from the solution of mixed rare earths. Of about 81% extraction and 69% stripping were obtained at a pH of feed solution of 5.5, 10% (v/v) of Cyanex 272 in kerosene, 6 M HCl and equal volumetric flow rates of feed and stripping solutions of 100 mL/min. The maximum percentages of extraction and stripping of 91 and 75, respectively were attained at 250 min.The distribution ratio (D) of 4.68 and the permeability (P) of 6.37 x 10-2 cm/s were obtained. The aqueous-phase mass transfer coefficient (ki) and the organic-phase mass transfer coefficient (km) were 0.013 and 0.788 cm/s, respectively. Since km is much larger than ki, it is indicated that the rate controlling step is the diffusion of praseodymium ions through the film layer between feed solution and liquid membrane.
