Reducing the Competition: A Dual-Purpose Ionic Liquid for the Extraction of Gallium from Iron Chloride Solutions.

Luke M M Kinsman,Jason B Love,Bryne T Ngwenya,Carole A Morrison

doi:10.3390/molecules25184047

Luke M M Kinsman, Jason B Love + Show 2 more

Open Access

https://doi.org/10.3390/molecules25184047

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Journal: Molecules (Basel, Switzerland)	Publication Date: Sep 4, 2020
Citations: 7	License type: CC BY 4.0

Affiliation: University of Edinburgh

Abstract

The separation of gallium from iron by solvent extraction from chloride media is challenging because the anionic chloridometalates, FeCl4− and GaCl4−, display similar chemical properties. However, we report here that the selective separation of gallium from iron in HCl solution can be achieved using the dual-purpose ionic liquid methyltrioctylammonium iodide in a solvent extraction process. In this case, the reduction of Fe3+ to Fe2+ by the iodide counterion was found to inhibit Fe transport, facilitating quantitative Ga extraction by the ionic liquid with minimal Fe extraction from 2 M HCl.

Highlights

Gallium is an important component in materials used in modern electronic devices such as light-emitting diodes (LEDs) and solar panels and is exploited in biomedical, pharmaceutical, and radiopharmaceutical applications, owing to the similar chemical properties of Ga3+ and Fe3+
There are no abundant natural sources of gallium; instead, it is primarily extracted as a by-product of bauxite and zinc ore processing [3,4]
The crude mixture was concentrated under vacuum to yield a viscous orange oil (100%) and diluted with toluene to form a 1.0 M stock solution

Summary

Introduction

Gallium is an important component in materials used in modern electronic devices such as light-emitting diodes (LEDs) and solar panels and is exploited in biomedical, pharmaceutical, and radiopharmaceutical applications, owing to the similar chemical properties of Ga3+ and Fe3+cations [1,2]. Due to its limited supply in nature, it is considered a critical element, and so its recovery from alternative sources such as coal fly-ash, mine tailings, or electronic waste is important [3,5,6]. In these cases, the presence of iron poses challenging selectivity issues in its separation, for example, by solvent extraction. ILs such as trioctylammonium chloride ([TOAH][Cl]) and methyltrioctylammonium chloride ([MTOA][Cl]) have been widely reported as reagents for the recovery of gallium and iron by solvent extraction [9,10,11]

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