Novel reverse mixed micelle mediated transport of platinum and palladium through a bulk liquid membrane from real samples

摘要

A facilitated uphill transport for the separation and pre-concentration of platinum and palladium through a bulk liquid membrane procedure utilizing reverse mixed micelles as transport vehicles was developed. A mixed micellar solution in a liquid membrane process is a representation of mixed monolayer at the feed/membrane interface, and mixed bilayer aggregate in the membrane/receiving interface. A cationic hydrophobic surfactant along with, a nonionic surfactant was used to form reverse mixed micelles in tri-chloroethylene, which act as a carrier for extracting the metal ions into bulk liquid membrane. This procedure is based on the formation of hydrophobic ion-associates of platinum and palladium with the reverse mixed micelles in the presence of an acid mixture which are extractable into the membrane phase. The formation of reverse mixed micelles hastens the transport of platinum and palladium into the organic phase making room temperature extraction feasible providing an energy efficient extraction. These ion associates are then stripped into the receiving phase from these reverse mixed micelles. Several factors influencing the extraction efficiency, such as the acid concentration, surfactant concentration, extraction time and temperature were investigated and optimized for providing better recoveries. The formation of reverse micelles and reverse mixed micelles has been analyzed using TEM (transmission electron microscope). The preconcentration factors for both platinum and palladium individually were found to be 10 using this method. The accuracy of the procedure was validated by analyzing PTM-1a nickel-copper sulfide matte. The procedure has been utilized for the recovery of platinum and palladium from spent catalytic converters and environmental samples.