Highly efficient gold recovery from acidic E-waste leaching solution using porous chitosan beads

Abstract

Porous Chitosan beads with high surface area were prepared for adsorption of gold by lyophilisation of glutaraldehyde-crosslinked-chitosan (GCC) beads. The prepared porous GCC beads showed two-fold larger adsorption kinetics and capacity for Au(III) ion compared to the GCC beads prepared without the lyophilisation treatment. The superior performance of porous GCC beads could be attributed to more rapid diffusion of Au(III) ion and higher adsorption surface area than the regular GCC beads (BET surface areas of 212.8 m2g-1 vs. 0.17 m2g-1 for the porous vs. regular GCC beads). The porous GCC beads were also found to adsorb Au(III) ion selectively from actual acidic E-waste leaching solution. The adsorbed Au(III) ion on the porous GCC beads was reduced to Au(0), which was supported by EDS and XRD analyses. The adsorbed gold could be effectively desorbed by using acidic thiourea solution (0.1 M HCl and 0.4 M thiourea). Overall, the porous GCC beads prepared in this study promises a high potential for a selective recovery of gold from E-wastes.