REACTIVE LIQUID-LIQUID-EXTRACTION OF HEAVY-METALS FROM LEACHATE WITH OIL-SOLUBLE COMPLEXING SURFACTANTS

Reactive liquid-liquid extraction is a well-known technology for the s elective winning of metals. However, the application of this method in environmental processing, such as the non-selective separation of hea vy metals from waste water (e.g. leachate from landfills), is new. It is shown that technical oil-soluble surfactants with complexing proper ties are able to lower,the content of simultaneously present heavy met als by about two or three orders of magnitude, starting at 10-100 mg l (-1). By applying commercially available quinolines (such as LIX26(R)) and oximes (such as LIX84(R)), it is possible to extract the heavy me tals Cu, Cr, Cd, Ni, Zn and Pb in one step, keeping within the limits set by the German authorities. Bulk metals such as Ca remain in the wa ste water. Besides fundamental investigations on the stoichiometry of the extracting reaction, the extraction selectivity and the phase sepa ration, experiments concerning the extraction and re-extraction speed using a continuously operating mixer-settler were performed.