Selective leaching of Ni from Cd-depleted spent Ni-Cd batteries by glycine-citrate solution

•Leaching of Ni from Cd-depleted spent Ni-Cd battery using glycine & citrate mixture.•95% of Ni was selectively leached using 1 mM Gly, 34 mM Na3Cit, at 55 °C after 36 h.•Proposing a rate-model for Ni dissolution versus t, T, S/L, Gly & Cit concentration.•Predicting probable Ni dissolution reactions by thermodynamic modelling.