Industrial & Engineering Chemistry Research, Vol.55, No.49, 12644-12654, 2016
DTDGA-Impregnated XAD-16 Beads for Separation of Gold from Electronic Waste Solutions
DTDGA-extractant-impregnated XAD-16 polymeric beads (DTGA-XAD-16) were synthesized and evaluated for the separation of gold from electronic waste solutions. Batch sorption studies were carried out to understand the effects of various physical parameters on the recovery of gold from aqueous media. These synthesized beads were characterized by various techniques, namely, FTIR spectroscopy, optical microscopy, SEM, and TGA, to gain insight into the composition and morphology of the beads. Kinetics measurements showed that an equilibration time of about 180 min was sufficient to remove the saturation amount of gold from the solution. Further, various kinetic modeling analyses of the extraction results were carried out using pseudo-first order, pseudo-second-order, and intraparticle-diffusion equations, and the corresponding rate constants were determined. The maximum experimental sorption capacity of the beads was found to be similar to 35 mg g(-1). The equilibrium sorption data were fitted to different isotherm models and were found to be represented well by the Langmuir sorption isotherm equation. Stripping of the sorbed metal from the beads can easily be achieved using 0.01 M thiourea in 0.1 M HCl. The reusability of the beads was also established by multiple sorption-desorption experiments. The synthesized beads exhibited the highly selective extraction of gold from simulated electronic waste solutions.