SORPTION AND SEPARATION OF PALLADIUM, PLATINUM AND GOLD CHLOROCOMPLEXES BY MEANS OF A DIPICOLINIC ACID POLYSTYRENE-BASED CHELATING RESIN

A chelating ion-exchange resin containing dipicolinic acid as functional group and based on microporous chloromethylated cross-linked polystyrene-divinylbenzene (2%) copolymer has been prepared. Its sorption and desorption characteristics for Pd(II), Pt(II), Pt(IV) and Au(III) have been studied in aqueous chloride solutions under a number of experimental conditions, both in batch and in column, at room temperature and constant ionic strength (mu = 1 mol/l, KCl/HCl). In column operations at pH 6, Pd(II) can be separated from Pt(II) or Pt(IV) owing to the different rate of formation of the immobilized chelated species. From a mixture of Pd(II), Pt(IV) and Au(III) at pH 6, Pt(IV) flows unaffected, whereas Au(III) and Pd(II) are both retained and successively separated by selective elution. From the same mixture at pH less-than-or-equal-to 0 only Au(III) is sorbed by anionic exchange.