Co(II) and Ni(II) transport from model and real sulfate solutions by extraction with bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272)

Jakub Stefaniak,Sara Karwacka,Małgorzata Janiszewska,Abhishek Dutta,Eldon R Rene,Magdalena Regel-Rosocka

doi:10.1016/j.chemosphere.2020.126869

Jakub Stefaniak, Sara Karwacka + Show 4 more

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https://doi.org/10.1016/j.chemosphere.2020.126869

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Abstract

This paper presents the results of Co(II) and Ni(II) extraction from model and real solutions using bis(2,4,4-trimethylpentyl)phosphinic acid (i.e. Cyanex 272) that are in agreement with waste-to-resources approach, i.e. the recovery of valuable components from wastes. The results from this study shows that, extraction using Cyanex 272 is an efficient method to recover Co(II) selectively from sulfate electrolytes obtained from the leaching of steel scraps of aircraft engines. The highest selectivity value (∼160) of Co(II) extraction over Ni(II) was obtained at a pH of 4.8, the lowest selectivity value (∼30) was observed at a pH of 5.5, while above this value the selectivity only increased slightly with increasing pH. A pH of 5.2 was selected as a compromise between Co(II) selectivity and Ni(II) amount in the organic phase. The essence of the investigation is to propose important parameters to extract Co(II) from real leach solutions, and to further recover valuable Co(II) from the loaded organic phase by stripping with 1 M H2SO4, thus producing an electrolyte of Co(II) for electrowinning – a possible alternative route for resource recovery. Small volume of the stripping phase (w/o = 1:5) used in this study, lead to an enrichment of sulfate electrolyte in Co(II), resulting in ∼50 g/dm3 of Co(II) in the solution, which is a great advantage of the approach proposed. Such a solution is a valuable source for the electrowinning of metallic cobalt, which can be used for the production of steel alloys, Li-ion batteries or catalysts.

Highlights

IntroductionJ. Stefaniak et al / Chemosphere 254 (2020) 126869 pure chemical compounds for pharmaceutical and biomedical applications, metal production, and different waste treatment processes (Rydberg, 2004; Alguacil and Regel-Rosocka, 2018)
Pre- and post-treatments of wastes are responsible for the success of the solvent extraction (SX) used in the recovery of metal, and places SX among a number of methods that fit the concept of waste-to-resources (WTR)
Theoretical distribution of species existing in a real leaching solution (Fig. 1a) and in a model solution after the precipitation of Al(III), Fe(III) and Cr(III) (Fig. 1b) was estimated using the Medusa program (Puigdomenech, 2018)

Summary

Introduction

J. Stefaniak et al / Chemosphere 254 (2020) 126869 pure chemical compounds for pharmaceutical and biomedical applications, metal production, and different waste treatment processes (Rydberg, 2004; Alguacil and Regel-Rosocka, 2018). Stefaniak et al / Chemosphere 254 (2020) 126869 pure chemical compounds for pharmaceutical and biomedical applications, metal production, and different waste treatment processes (Rydberg, 2004; Alguacil and Regel-Rosocka, 2018) It involves the transport of chemical substances from one phase into another, as well as the kinetics of the transport, and the final distribution of the substances between the two phases in equilibrium. Such an approach is in agreement with the circular economy concept proposed to minimize raw material input, waste generation and the dependence on the imports of raw materials (waste is considered as one of the key resources for manufacturing goods) (Van Eygen et al, 2016; Velenturf et al, 2019; Blomsma and Tennant, 2020)

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