A simplified model for the coupled transport of metal ions through hollow-fiber supported liquid membranes

This paper describes a simplified model for the carrier-facilitated transport of metal ions through hollow-fiber supported liquid membranes, HFSLM. The model leads to approximate and simple equations describing the concentration variations expected when an aqueous feed solution is flowing through the lumens of a HFSLM module. The equations incorporate simple and independently measurable parameters and apply to two situations: (a) a once-through mode, i.e., the feed solution passes only once through the module, and (b) a recycling mode, i.e., the feed solution is continuously recirculated through the module. The equations have been tested by measuring the transport of Cu²⁺ ions through microporous polypropylene hollow fibers containing a 0.3 F solution of bis(2-ethylhexyl)phosphoric acid in n-dodecane. HFSLM modules containing a variable number of fibers, fibers of different lengths and operated at different linear flow velocities have been used.