The characterisation of silver sorption by chelating resins containing thiol and amine groups

We investigated the sorption capacity towards Ag(I) of three different resi ns bearing a thiol chelating group, Duolite GT-73, Purolite Thiomethyl and Spheron Thiol, as well as Chelamine, a resin with a tetraethylenepentaamine moiety. The metal sorbed by the resins at 0.01 M HNO3 follows the order: P urolite Thiomethyl > Duolite GT-73 > Spheron Thiol. As this result does not correlate with the sulphur content of each resin we studied the physical c haracteristics of the resins in an attempt to find an explanation for this behaviour. In the case of Chelamine, a nitrogen containing resin, silver so rption increases when pH increases, reaching a value of 1.2 mmol/g at pH ar ound 6. A kinetic study of the three polymers with the same functional grou p (-SH) was also performed in order to discover more about the sorption mec hanism. The differences observed between the three polymers are explained t aking into consideration the nature of the polymeric matrix and the resin m orphology. Finally, we study the elution process of silver and find that, w ith each resin, thiourea 0.1 M in HNO3 0.1 M is the most effective elution agent.