(265c) Industrial Implementation of Heavy Metal Recycling with Supported Liquid Membranes

Major advantage of liquid membrane permeation over liquid/liquid extraction is the generation of a permanent maximum driving force. Hence liquid membrane permeation can be classified as low cost technology. Status of industrial application of liquid membrane permeation has not yet been achieved because of membrane bleeding. Membrane bleeding leads to short circuiting of the raffinate phase and the stripping phase.

Aim of the present research project is to improve stability and accuracy of supported liquid membranes for industrial implementation by avoiding short circuiting with technical measures such as regeneration of the membrane phase and reimpregnation of the support layer. Experimental tests were carried out with the test system Zn2+/DEHPA/H+. The effect of technical measures on mass transfer and accumulation of Zn2+ in phase I (stripping phase) was quantified and considered in the scale up strategy.

Summary of results

Mass transfer is not affected by regeneration of the membrane phase. Scrubbing loss of ion exchanger is not significant Continuous reimpregnation of the support layer by solvent flux cross-current to the mass transfer direction increases mass transfer. Cross current solvent flux does neither affect the metal ion load of the solvent phase negatively nor does it outsmart the thermodynamic barrier for counter transport even for metal ion enrichment factors in the strip phase in the range of 100.

Finally technical scale up of the process with a scale up factor of 69 has successfully validated the results of mass transfer investigation.