Kinetic study and modelling of silver dissolution in synthetic industrial silver electrolyte as a function of electrolyte composition and temperature. (1st July 2018) - Aji, Arif T.
Highlights: Use of microelectrode effect improved accuracy of Ag dissolution kinetic modelling. Optimum overpotential range of silver electrorefining is within 150–200 mV. Models show that [Ag + ], [HNO3 ] and T have positive impact to the Ag dissolution. Increasing [HNO3 ] and T reduce the current efficiency due to Ag re-dissolution. [HNO3 ] needs to be limited to below 5 g/dm 3 for high current efficient process. Abstract: The kinetics of silver dissolution in silver electrorefining process was investigated using a series of synthetic electrolytes and different electrode sizes. Kinetic models at corrosion potential and industrial range overpotentials were constructed as a function of electrolyte composition and temperature. The results revealed that overpotential of 150–200 mV vs. corrosion potential represented the values corresponding to the industrial silver electrolysis. In order to achieve a high current efficiency in silver electrorefining, our kinetic models suggest that concentration of HNO3 should be less than 5 g/dm 3 or 3 g/dm 3 for operation at 25 °C and 45 °C, respectively.