Selective Lithium–Magnesium Separation from Brines by Ionic-Liquid Solvent Extraction: Molecular Mechanisms, Extractant Design, and Process Optimization
6 affiliations
- 1Departamento de Ingeniería Química y Procesos de Minerales, Facultad de Ingeniería, Universidad de Antofagasta, Antofagasta 1240000, Chile
- 2Departamento de Ingeniería en Metalurgia, Universidad de Atacama, Copiapó 1531772, Chile
- 3Departamento de Ingeniería Metalúrgica y Minas, Universidad Católica del Norte, Antofagasta 1270709, Chile
- 4Facultad de Ingeniería, Universidad San Sebastián, Sede Concepción, Concepción 4030000, Chile
- 5Centro de Desarrollo Energético Antofagasta, Universidad de Antofagasta, Antofagasta 1240000, Chile
- 6Faculty of Engineering and Architecture, Universidad Arturo Prat, Avenida Arturo Prat 2120, Iquique 1110939, Chile
Abstract
The growing global demand for lithium (Li+), driven by its strategic role in energy storage technologies, faces a critical challenge in its recovery from brines: the selective separation of Li+ and magnesium (Mg2+) ions. Because Li+ (ionic radius ≈ 76 pm) and Mg2+ (≈ 72 pm) have almost identical ionic radii despite their different charge, their coordination and hydration behaviour are difficult to discriminate at the molecular level. The high Mg2+ content in natural brines, such as those from the Atacama Salar, delays the efficiency of conventional extraction processes, which also result in significant Li+ losses. In this context ionic liquids (ILs) are emerging as alternative solvents with tunable properties, low volatility, and high thermal stability, although their environmental performance depends strongly on their chemical structure, toxicity, aqueous solubility, and recyclability, offering advantages over traditional organic extractants. This study evaluates the use of ionic liquids in liquid–liquid extraction systems for the selective removal of Mg2+, analysing operational parameters such as pH, organic-to-aqueous phase ratio (O/A), and extractant concentration. This review critically compares ionic-liquid-based extraction systems by relating Mg2+/Li+ selectivity to extractant structure, coordination chemistry, and key operational variables, while also considering the main limitations associated with their application to high-salinity brines. By linking macroscopic extraction performance to the underlying coordination chemistry, hydration-shell disruption, and computational screening tools such as quantum chemical calculations and COSMO-RS, this approach supports the rational, molecular-level design of environmentally responsible extractants for brines with a high Mg/Li ratio.
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BibTeX
@article{mura2026selective,
title = {{Selective Lithium–Magnesium Separation from Brines by Ionic-Liquid Solvent Extraction: Molecular Mechanisms, Extractant Design, and Process Optimization}},
author = {Mauricio Mura and Jonathan Castillo and Edelmira Gálvez and Williams Leiva and Pía Hernández and Felipe M. Galleguillos-Madrid and Rossana Sepúlveda and Norman Toro},
journal = {International Journal of Molecular Sciences},
year = {2026},
month = oct,
doi = {10.3390/ijms27209005},
url = {https://www.mdpi.com/1422-0067/27/20/9005},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Selective Lithium–Magnesium Separation from Brines by Ionic-Liquid Solvent Extraction: Molecular Mechanisms, Extractant Design, and Process Optimization
AU - Mauricio Mura
AU - Jonathan Castillo
AU - Edelmira Gálvez
AU - Williams Leiva
AU - Pía Hernández
AU - Felipe M. Galleguillos-Madrid
AU - Rossana Sepúlveda
AU - Norman Toro
PY - 2026
DA - 2026/10/01
JO - International Journal of Molecular Sciences
DO - 10.3390/ijms27209005
UR - https://www.mdpi.com/1422-0067/27/20/9005
AB - The growing global demand for lithium (Li+), driven by its strategic role in energy storage technologies, faces a critical challenge in its recovery from brines: the selective separation of Li+ and magnesium (Mg2+) ions. Because Li+ (ionic radius ≈ 76 pm) and Mg2+ (≈ 72 pm) have almost identical ionic radii despite their different charge, their coordination and hydration behaviour are difficult to discriminate at the molecular level. The high Mg2+ content in natural brines, such as those from the Atacama Salar, delays the efficiency of conventional extraction processes, which also result in significant Li+ losses. In this context ionic liquids (ILs) are emerging as alternative solvents with tunable properties, low volatility, and high thermal stability, although their environmental performance depends strongly on their chemical structure, toxicity, aqueous solubility, and recyclability, offering advantages over traditional organic extractants. This study evaluates the use of ionic liquids in liquid–liquid extraction systems for the selective removal of Mg2+, analysing operational parameters such as pH, organic-to-aqueous phase ratio (O/A), and extractant concentration. This review critically compares ionic-liquid-based extraction systems by relating Mg2+/Li+ selectivity to extractant structure, coordination chemistry, and key operational variables, while also considering the main limitations associated with their application to high-salinity brines. By linking macroscopic extraction performance to the underlying coordination chemistry, hydration-shell disruption, and computational screening tools such as quantum chemical calculations and COSMO-RS, this approach supports the rational, molecular-level design of environmentally responsible extractants for brines with a high Mg/Li ratio.
SN - 1422-0067
ER -