Reaction dependent extraction of copper and nickel using hollow fibers

The competitive extraction of copper and nickel with kerosene solutions of HDEHP [di-(2-ethylhexyl) phosphoric acid] has been studied in a hollow fibe r membrane module. The data showed that the reaction changes from first ord er to second order as the extraction proceeds. The first-order behavior lar gely results from mass transfer resistances in the membrane and in the aque ous boundary layer. The second-order reaction, occurring in dilute solution , is a consequence of an interfacial reaction. The results have implication s for other metals. (C) 2000 Elsevier Science B.V. All rights reserved.