Studies on Separation of Heavy Metals from Acidic Solutions by Foam Fractionation with Respect to an Application on Acidic Soil Extracts

Abstract

An experimental investigation is presented on the batch foam fractionation of the heavy metal cations PbZ+, Cd2+, Cuz+, Sb3+ and As5+ from diluted aqueous solutions with hexamethylenedithiocarbamate (HMDC) as complexing agent and sodiumdodecylsulfate (SDS) as surfactant. Among the considered pH-values of 2,4 and 7 the pH 2 experiments allow a direct application of foam fractionation on acidic extracts from heavy metal contaminated soil. The experiments at pH 2 and pH 4 show better results than those at hexamethylenedithiocarbamate, surfactants neutral pH. Although a simple device was used, a maximum enrichment factor of 13.8 and a minimum removal factor of 0.01 have been measured. The flotation with weak organic acids like citric acid (CA) and acetic acid (AA) show about 50 -70% smaller enrichment factors than those acidified with hydrochloric acid. The dissolution and mixing of the reacting components as well as the concentration of the detergent and the gaseous volume flow can be regarded as basic parameters of foam fractionation. * Dip1.-Ing. Simone Wommel, P. D. Dr.-Ing. habil. Wolfgang Calmano, Technische Universitat Hamburg-Harburg, Arbeitsbereich Umweltschutztechnik, Eissendorferstr. 40, W-2100 Hamburg 90, Germany Correspondence to W. Calmano Acta hydrocbim. hydrobiol. 20 (1992) 5, m-m 0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1992 0323-4320/92/0511-0265 $03.50+25/0