Extractive recovery of palladium(II) from hydrochloric acid solutions with Cyphos®IL 104

Abstract

Extractive recovery of palladium(II) from a hydrochloric acid solution with quaternary phosphonium salt: trihexyl(tetradecyl)phosphonium bis-(2,4,4-trimethylpentyl)phosphinate (Cyphos®IL 104) as a novel reagent in the presence of toluene has been investigated. Extraction data indicate that Cyphos®IL 104 is a very efficient and fast extractant. The increase in HCl concentration has negative influence on the extraction and 96 and 52% of palladium(II) ions can be effectively extracted with Cyphos®IL 104 from 0.1 and 3.0M HCl, respectively. The equilibrium of palladium(II) extraction from aqueous 0.1 and 3.0M HCl with this phosphonium ionic liquid is achieved after 5min. Extraction of palladium(II) with Cyphos®IL 104 proceeds at the interface according to the anion-exchange mechanism. The best stripping solution from among the studied ones is 0.5M NH4OH. The feasibility of reuse Cyphos®IL 104 in several cycles of extraction-stripping process was also examined. Increase in temperature from 20 to 70°C causes a negligible decrease in the palladium(II) extraction. The calculated values of ΔH°, ΔS° and ΔG° evidence that the extraction of palladium(II) with Cyphos®IL 104/toluene mixture is an exothermic reaction both from 0.1 and 3.0M HCl solutions.