Gold recovery from chloride solutions with XAD-7: Competitive adsorption of Fe(III) and Te(IV)

Adsorption of gold and iron can be explained satisfactorily by taking into account the formation equilibria of the tetrachloro complexes and the difference in their acid strengths. The uptake of the weakly acidic HAuCl4 depends only slightly on the HCl concentration and adsorption was substantially stronger in NaCl solutions. The opposite trends observed for iron were due to the lower stability and higher degree of dissociation of HFeCl4. The adsorbable complex of Te(IV), HTe(OH)Cl4, has lower affinity for the adsorbent, but at high concentrations it can reduce substantially the adsorption capacity for Au(III) and Fe(III). This effect was confirmed with the adsorption column runs, and the change in the break-through behavior of Au(III) and Fe(III) can be explained quantitatively by the simulation model.