ELECTROCHEMICAL DEPOSITION OF SILVER FROM A LOW CYANIDE CONCENTRATIONBATH

The silver reduction process was studied in a new, low cyanide concent ration solution in which the predominant species is the ion Ag(CN)(2)( -) and the pH is fixed by the presence of potassium pyrophosphate. The electrochemical reduction of silver occurs via an adsorbed electroact ive species assumed to be Ag(CN)(2)(-). The silver reduction appears t o be a quasi-reversible process at 20 degrees C, and its kinetic param eters are presented as well as the effect of temperature in a 10 to 60 degrees C range; silver reduction is fast when the temperature is hig h, and the activation energy was evaluated. Linear sweep voltammetry a nd the use of an electrochemical quartz crystal microbalance prove the existence of the adsorbed electroactive species and additional eviden ce was found by chronopotentiometry.