Leaching behavior of nickel from waste multi-layer ceramic capacitors

The leaching behavior of nickel present in waste multi-layer ceramic capacitors (MLCC) was studied using different acidic leaching reagents in a stirred batch reactor. The waste MLCC consisted of multi-layered ceramic BaTiO3 and inner nickel electrodes arranged like a sandwich. The effects of acid leaching reagent, its concentration, agitation speed, particle size, and leaching temperature on the leaching of nickel from waste MLCC were examined. HNO3 was found to be most effective leaching reagent in comparison to HCl and H2SO4. The fraction of Ni leached was found to be 97% for a pulp density of 5 g/L and temperature 90 °C in an agitation time of 90 min. The leaching rate of nickel was limited by the diffusion of HNO3 solution throughout thin channels that were formed between BaTiO3 layers during the leaching of nickel. The Jander equation was also found to fit well with the leaching rate data. The leaching of nickel follows a first order rate reaction with HNO3 concentration and has an activation energy of 37.6 kJ/mol (9.0 kcal/mol).