Separation of Palladium(II) from Aqueous Chloride Solution Using Tridodecylammonium Chloride in Toluene as Extractant

Abstract

A study on the separation of Pd(II) from chloride solutions by a solvent extraction process is presented. Organic solutions containing tridodecylammonium chloride (TLAHCl) in toluene were used as the extracting phase. The process determines the chemical species produced in the extraction reactions by analyzing, over a wide range of conditions, the equilibrium state of the system. The study, based on metal distribution measurements, includes the effect of aqueous chloride ion on the stability of the extracted species which affect the yield of palladium extraction. The extraction phenomena can be explained by assuming the following reactions: Pd²⁺+2Cl-+ TLAHCI_??_PdCl₂TLAHCl, Pd²⁺2Cl-+2TLAHCl_??_PdCl₂(TLAHCl)₂, Pd²⁺+2Cl-+3TLAHCl_??_PdCl₂(TLAHCI)₃. These reactions give the best fit to the experimental information. The results obtained at 1.0, 2.0 and 3.0mol dm^-3 of aqueous chloride have been correlated in terms of ionic interactions.