Dissolution of metallic silver with ammonium acetate and hydrogen peroxide solution as a greener substitute for cyanide: kinetics study

This work investigates the kinetics of metallic silver dissolution in ammonium acetate solutions with hydrogen peroxide as the oxidizing agent. The study systematically examines the influence of temperature, reagent concentrations, and rotation speed on leaching performance. The results demonstrate that the dissolution rate increases with higher rotation speeds and with ammonium acetate concentrations in the range of 0.025–0.150 M. Hydrogen peroxide concentrations up to 0.20 M significantly enhance dissolution, while further increases provide minimal benefit. Temperature between 20 and 45 °C was favorable due to the stability of hydrogen peroxide in this range. The dissolution rate was found to follow the Levich model, showing proportionality to the square root of rotation speed. The calculated activation energy of 10.58 kJ/mol indicates diffusion control as the rate-determining step.