Ionic Liquid Extraction for Sodium Removal from Lithium Brine
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Solution Overview
Problem
Conventional methods for isolating and purifying lithium from lithium-containing solutions, such as terrestrial and geothermal brines, are energy-intensive, time-consuming, and inefficient, particularly due to the reliance on thermal or solar evaporation and limited selectivity of solvent extraction techniques for lithium over other ions like sodium and potassium.
Innovation Solution
A method involving the selective removal of sodium and/or potassium from lithium-containing solutions using a hydrophobic solution containing a hydrophobic solvent, a lipophilic protic ionic liquid, and lipophilic sodium- or potassium-selective complexing ligands, which transfers these ions out of the aqueous phase into a hydrophobic phase, thereby purifying lithium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal or solar evaporation is used to isolate lithium from lithium-containing solutions, then lithium salts can be produced, but the process becomes energy-intensive and time-consuming (18-24 months)
Solution Approach 1:
The invention changes the fundamental parameter of the separation process from thermal evaporation to solvent extraction using ionic liquids. This parameter change enables selective extraction of lithium at ambient or mild conditions, eliminating the need for energy-intensive heating and reducing processing time from 18-24 months to a much shorter period.
Solution Approach 2:
The invention replaces the mechanical/thermal evaporation system with a chemical extraction system using ionic liquids. The ionic liquids selectively complex with lithium ions through chemical interactions, allowing separation without thermal input and dramatically reducing energy consumption while maintaining reliable lithium isolation.
2Reliability
If solvent extraction techniques are used to selectively remove lithium from lithium-containing solutions, then lithium can be isolated, but the selectivity for lithium over other cations (sodium and potassium) is limited and the complexing molecules are costly
Solution Approach 1:
The invention changes the chemical parameters of the extractant by using ionic liquids with specific anions (e.g., [TF2N]−, [Tf2N]−) that have high affinity for lithium ions. This parameter change in the extractant chemistry enables superior lithium selectivity over sodium and potassium while the ionic liquid structure allows for cost-effective synthesis and regeneration.
Solution Approach 2:
The invention employs composite ionic liquid systems combining specific cations and anions that work synergistically to enhance lithium selectivity. The composite nature of the ionic liquid (combining organic cations with specialized anions) creates a material with both high selectivity and improved manufacturability compared to conventional complexing molecules.
3Reliability
If conventional evaporation methods are used, then lithium salts can be produced, but water consumption is high and water management becomes problematic, especially in arid regions
Solution Approach 1:
The invention replaces the water-intensive evaporation process with a solvent extraction system using ionic liquids. The ionic liquids serve as the extraction medium and can be regenerated and reused, eliminating the need for large volumes of water for both processing and cooling, thus solving the water consumption and management problems in arid regions.
Solution Approach 2:
The invention implements a recovery system where the ionic liquid extractant is regenerated after lithium extraction. The spent ionic liquid is treated to recover lithium salts, and the regenerated ionic liquid is reused in subsequent extraction cycles, minimizing waste and eliminating the need for continuous water input required by evaporation methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a cost-effective and efficient method for isolating and purifying lithium, reducing the need for energy-intensive evaporation processes and improving selectivity over other ions, achieving high separation factors for sodium and potassium from lithium.
Implementation Method 1
contacting an aqueous lithium-containing solution with a hydrophobic solution containing: (a) a hydrophobic solvent, (b) a lipophilic protic ionic liquid containing a conjugate base of a superacid, and (c) a lipophilic sodium-selective or potassium-selective complexing ligand, with the end result of selectively removing sodium and/or potassium ions from the aqueous lithium-containing solution and transferring them to the hydrophobic solution
Implementation Method 2
a lipophilic sodium-selective or potassium-selective complexing ligand
Data Source
AI summary
A method for selectively removing sodium or potassium from an alkaline lithium-containing aqueous solution, the method comprising: (i) contacting the alkaline lithium-containing aqueous solution with a hydrophobic solution comprising: (a) an aqueous-insoluble hydrophobic solvent, (b) a protic ionic liquid of the formula X−Y+, wherein X− is a conjugate base of a superacid and Y+ is a protonated cation, and (c) at least one of lipophilic sodium-selective and potassium-selective complexing ligands, wherein the contacting step results in selective complexation with and removal of sodium and/or potassium ions from the lithium-containing aqueous solution into the hydrophobic solution along with simultaneous abstraction of a proton from Y+ to form Y; and (ii) separating the aqueous solution from the hydrophobic solution, wherein, in some embodiments, X− is a bis(sulfonyl)imide and Y+ is a protic ammonium species. The method may further include stripping sodium and potassium ions from the hydrophobic solution and regenerating Y+.