Treatment of alloy-electroplating wastewater by an automated solvent extraction technique

Electroplating with highly toxic metals is being gradually replaced by alloy or mixed-metal electroplating. We developed a solvent extraction method for the treatment of waste rinsewater generated in Zn-Co alloy electroplating, based on the studies of the extraction properties. An alkyl ester of an alkylphosphonic acid (PC-88A) or a dialky phosphinic acid (Cyanex 272) was used as the extractant. The two metals were co-extracted into the organic solvent and then separately recovered in a simple process. The feasibility of the process was demonstrated with automated mixer-settler solvent extraction units.