Separation and recovery of palladium(II) from base metal ions by melamine-formaldehyde-thiourea (MFT) chelating resin

Abstract

Melamine-formaldehyde-thiourea (MFT) resin, a chelating resin, was synthesized by reaction with melamine, formaldehyde and thiourea in aqueous solution. This chelating resin was used in the separation and recovery of palladium(II) from copper(II) and zinc(II) base metal ions. Effect of initial acidity, adsorption capacities of the metal ions by batch method and adsorption, elution, separation factors and column adsorption capacity of the metal ions by column method were examined. The optimum initial acidity was determined as pH 4. Adsorption capacities of the MFT resin were found as 15.29 mg/g (0.144 mmol/g) for palladium(II), as 1.612 mg/g (0.025 mmol/g) for copper(II) and as 0.453 mg/g (0.007 mmol/g) for zinc(II). In addition the protonation capacity of the resin was found as 0.110 mmol H+/g. It was concluded that ionic interaction between protonated amines on the resin and chloro-palladate complex (PdCl42-) Was very effective as well as chelation. In the column studies, dynamic adsorption capacities were calculated as 1580 mu g/g (14.85 mu mol/g) for palladium(II), as 250 mu g/g (3.93 mu mol/g) for copper(II) and as 25 mu g/g (0.38 mu mol/g) for zinc(II). MFT resin showed higher affinity to palladium(II) ions according to copper(II) and zinc(II) ions. It was seen that palladium(II) can be separated from copper(II) and zinc(II) and concentrated by melamine-formaldehyde-thiourea chelating resin. (C) 2008 Elsevier B.V. All rights reserved.