Green separation of lanthanum, cerium and nickel from waste nickel metal hydride battery


In a circular economy context, there is a growing need for more sustainable waste management options to recover elements from end-of-life materials. These secondary ores represent a source of critical elements that are often present in higher concentration compared to their primary ore. In this work, the recovery of lanthanum (La) from waste nickel metal hydride battery (NiMH) leachate is investigated using an aqueous biphasic system (ABS) process based on a pluronic triblock copolymer (L35). An initial screening is performed to determine the influence of the ABS phase forming salt anion and alizarin red extractant on the La extraction efficiency and selectivity. From these results, a three-step ABS process is developed, varying only the nature of the salt and requiring no additional extractant. In a first step, the ABS composed of L35 + thiocyanate ammoniun + H2O efficiently extracts iron, manganese, and cobalt leaving La, cerium, and Ni in solution. Nickel is subsequently recovered by precipitation using dimethylglyoxime. Finally, La is separated from cerium using the L35 + ammonium nitrate + H2O ABS, recovering 62 g of La with 94% purity per kilogram of black mass of NiMH battery. This work highlights the applicability of ABS for the treatment of raw and complex matrices, potentially allowing for a greener hydrometallurgical treatment of wastes. (C) 2021 Elsevier Ltd. All rights reserved.

subject category

Engineering, Environmental; Environmental Sciences


Vargas, SJR; Schaeffer, N; Souza, JC; da Silva, LHM; Hespanhol, MC

our authors


The authors acknowledge the Conselho Nacional de Pesquisa e Desenvolvimento Tecnologico/Instituto Nacional de Ciencias e Tecnologias Analiticas Avancadas (CNPq/INCTAA 465768/2014-8), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior/Fun dacao para a Ciencia e Tecnologia (CAPES/FCT 88881.309048/2018-01), and Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) for the financial support. S.J.R.V. and J.C.S. acknowledge CAPES for research studentships. M.C.H. and L.H.M.S. acknowledge the research fellowships awarded by CNPq (306329/2017-4 and 306642/2019-0).

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