Highly selective transport of palladium from electroplating wastewater using emulsion liquid membrane process

• The selectivity of Cyanex 302 toward palladium and chromium ions in electroplating wastewater was investigated.
• The optimal conditions were suggested.
• The percentage of extraction was around 100%.

A new liquid membrane formulation containing phosphinic acid groups as a carrier was developed for the selective extraction of palladium (Pd) from electroplating wastewater using emulsion liquid membrane (ELM) process. The important parameters that affect the membrane stability and the recovery of Pd were investigated, such as extraction time, concentrations of carrier and stripping agents, pH of feed phase, and treat ratio. Furthermore, at the optimum condition, the performance of Pd extraction was evaluated using real matrices solution. All experiments were carried out using batch extraction process and the recovery stage at high voltage demulsifier was employed. The results showed that the favorable conditions obtained for the extraction and the recovery processes were at 0.2 M of Cyanex 302, 1.0 M thiourea in 1.0 M H2SO4 of stripping agent, 1:3 treat ratio, pH 3 of feed phase, and 5 mins of extraction time. At these conditions, the maximum extraction and recovery of the Pd was 97% and 40%, respectively. Moreover, the result from the real matrices showed that almost 100% of Pd was extracted selectively over chromium at these conditions.

Schematic diagrams of ELM process for Pd extraction and recovery process Figure optionsDownload as PowerPoint slide