Hollow-fiber membrane extraction of copper(II) from aqueous ethylenediaminetetraacetic acid solutions with Aliquat 336

The extraction of Cu(II) from an equimolar EDTA ethylenediaminetetraacetic acid (EDTA) solution across microporous hollow fibers to an organic phase containing Aliquat 336 (a quaternary amine) was studied. It was shown that the resistance of interfacial chemical reaction could be neglected. A mass-transfer model was proposed considering aqueous- layer diffusion, membrane diffusion, and organic-layer diffusion on the basis of a good knowledge of extraction chemistry and the transport properties of the relevant geometry. The calculated time profiles of Cu(II) concentrations were in reasonable agreement with the measured ones (average standard deviation, 12%). The mass-transfer mechanism of this membrane extraction process was finally identified and discussed.