Adsorption and desorption of a gold–iodide complex onto cellulose acetate membrane coated with polyaniline or polypyrrole: a comparative study

Cellulose acetate membranes (M1) with controlled thickness were coated with an electroconductive polymer, and the resulting composites were characterized by SEM, XPS, electrical conductivity, and mechanical measurements. A comparative study of M1 coated with polyaniline (PANI) or with polypyrrole (PPy) for adsorption and subsequent desorption of a gold–iodide complex was performed. The PANI-coated M1 (M2) and that coated with PPy (M3) are effective adsorbents for recovery of the AuI2− complex. The adsorption of gold on the membranes was attributed to the exchange between the dopant ions and the AuI2− complex ions. The adsorption equilibrium data fitted the Langmuir isotherm model for both membranes M2 and M3. The desorption of the AuI2− complex with a NH4OH solution 3 M reached 97% for M3 membrane. This study shows a convenient method for the recovery of gold through the use of a complex with iodine without cyanide solutions.