Recovery of gold(III) and silver(I) on a chemically modified chitosan with magnetic properties

Chemically modified chitosan resin with magnetic properties has been prepared and investigated. The modification process took place through the reaction between chitosan and polymeric Schiff's base of thiourea/glutaraldehyde in the presence of magnetite. The resin obtained was tested for the recovery of Au(III) and Ag(I) from their aqueous solutions using batch and column methods. Uptake values of 3.6 and 2.1 mmol/g were reported for Au(III) and Ag(I), respectively. Both kinetics and thermodynamic parameters of the adsorption process were obtained. The data indicated that adsorption process is exothermic spontaneous reaction and kinetically proceeds according to pseudo second order model. The interaction mechanism between metal ion and active sites has been interpreted as ion pair for gold(III) and chelation for silver(I). Breakthrough time, critical bed height and durability of resin were estimated from column studies. These parameters indicated that the resin has a good efficiency towards Au(III) and Ag(I).