Effective Pd(II) carriers for classical extraction and pseudo-emulsion system

Abstract

This work aims to study the performance of three new extracting agents: N-decyloxy-1-(pyridin-3-yl)methaneimine (D-3MI), N-decyloxy-1-(pyridin-3-yl)ethaneimine (D-3EI) and N- decyloxy-1-(pyridin-4-yl)ethaneimine (D-4EI), in the solvent extraction of palladium. For this purpose, the effect of several parameters on the extraction of Pd(II) from hydrochloric acid medium was examined. The stripping of Pd(II), the stability of the extractant in multiple extraction/stripping cycles and the separation of Pd(II)/Pt(IV) were also investigated. After the classical solvent extraction studies, the Pseudo-Emulsion based Hollow Fibre Strip Dispersion (PEHFSD) technique was used for the recovery of Pd(II). The kinetics of permeation was found to be strongly dependent on the extractant concentration, the stripping of Pd(II) with thiourea being quite slower than its removal from the feed phase. The recovery of Pd(II) with the PEHFSD technique was also checked, using a commercial extractant, the amine Alamine 308, for comparison. The results obtained show that the ethaneimine D-3EI has the highest potential for extracting and stripping Pd(II) among the reagents tested. The use of 0.03 M D-3EI in toluene, as the membrane phase, allowed to remove practically all the metal content from the aqueous phase (100 ppm Pd, 1.5 M HCl) with relatively fast kinetics and led to a Pd(II) recovery above 90% for moderate permeation times.