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

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