Selective extraction of palladium from simulated liquid waste solution by emulsion liquid membrane process using D2EHPA as a mobile carrier

Abstract

Liquid semiconductor waste has become a serious problem to the environment due to the toxicity of heavy metals in the wastewater. However the monetary value of precious metals such as gold, silver and palladium has become a great concern nowadays. Therefore this study is investigating the recovery of palladium by emulsion liquid membrane (ELM) process using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as a carrier. The important parameters affecting the extraction of palladium such as concentrations of carrier and stripping agents, extraction time and treat ratio were investigate. This experiment was conducted using a mixer-settler in a batch system. The results showed that more than 90% of palladium was extracted using 0.05M D2EHPA, 0.1 M H2SO4 as a stripping agent, 5 minutes extraction time, and 1:3 treat ratio. However, the study on emulsion stability showed unstable results due to the leakage and swelling occurrence during the extraction process. As a conclusion, the research shows that ELM has the potential to extract palladium from simulated waste solution using D2EHPA as a mobile carrier.