Study of the mechanism of the electrochemical deposition of silver from an aqueous silver iodide suspension

The present work examines the reduction of solid silver iodide on a silver electrode and proposes a mechanism for this process. Voltammetric and coulometric studies for the steady and transient states showed adsorption of silver iodide at the electrode depending on its concentration; this adsorption is in accordance with the Langmuir isotherm for low concentrations and with multi-layer models (such as the BET isotherm) for higher concentrations. Reduction of silver iodide at the silver electrode can take place through several processes such as direct reduction of solid particles, or reduction of the adsorbed silver iodide and involves the formation of a dendritic silver deposit not adhering to the electrode and free iodide in solution. Silver is then recovered easily by filtration of the initial suspension.