LAUSR

Abstract Nickel (Ni) is a ferromagnetic and corrosion-resistant metal, whose demand has risen remarkably in recent years. Depletion of its sulphide and laterite ores has necessitated the need to find secondary sources of the metal. Spent nickel metal hydride (Ni-MH) batteries are considered to be possible sources of Ni recovery and recycling, and have been the object of some scientific investigations. This recovery is also important from environmental perspective, as disposal of the waste batteries constitute a significant release of Ni to the environment. However, previous studies have focused only on solvent extraction processes for Ni uptake from the battery leachates, neglecting the possibility of adsorption-based methods. Here, we optimized and achieved 99.6 % Ni uptake from the leachate of Ni-MH battery cathode, via the use of an adsorbing composite generated from 2-hydroxy-5-nonylacetophenone oxime (LIX-84I) and activated charcoal. Desorption with HCl led to the production of NiCl2.6H2O of 99.9 % purity, useful as a versatile industrial catalyst and for electroplating Ni onto other metals. The adsorption was endothermic and spontaneous, following a pseudo-second order kinetics while fitting best to Temkin isotherm model (R2 = 0.9913). This is the first report of an adsorption-based method optimizing Ni recovery from Ni-MH battery wastes.