Lithium in brine

Significance of the Topic

Lithium is essential for high-temperature lubricants, heat-resistant glass, and large-scale battery production.
Reliable quantification of lithium in brines is critical for assessing extraction feasibility and optimizing resource utilization.

Objectives and Overview of the Study

This study presents a potentiometric titration protocol to determine lithium concentration in brine samples by precipitating lithium as insoluble LiF and detecting the endpoint with a fluoride ion selective electrode.

Methodology

• Analyze two lithium chloride brine samples (~20% and ~40% m/m) without further preparation.
• Add ethanol to the sample to facilitate precipitation and ensure electrode coverage.
• Titrate with ammonium fluoride until the first equivalence point is reached.
• Monitor potential changes using a fluoride ISE to identify the endpoint.
• Account separately for potential calcium interference.

Instrumentation

• 907 Titrando high-end automated titrator with MSB connectors and iTrode electrodes.
• Combined fluoride-selective electrode with integrated Pt1000 temperature sensor for F− detection.

Main Results and Discussion

The method yielded reproducible results (n=3) for both samples.
Brine 1: mean LiCl content 41.3% with 0.7% absolute SD (1.6% rel).
Brine 2: mean LiCl content 14.85% with 0.11% absolute SD (0.7% rel).
The titration curves demonstrated clear endpoints and consistent performance.

Benefits and Practical Applications of the Method

• Cost-effective and faster than atomic absorption spectroscopy.
• Minimal sample preparation and straightforward operation.
• Suitable for routine QA/QC and economic assessment of lithium extraction.
• High reliability and reproducibility in complex brine matrices.

Future Trends and Potential Applications

Advances may include enhanced electrode selectivity, fully automated online monitoring, and extension to other alkali metal analyses.
Integration with process control systems could improve real-time resource management in lithium production.

Conclusion

Potentiometric titration using ammonium fluoride and a fluoride ISE in ethanol provides a reliable, rapid, and inexpensive approach for lithium determination in brines.
This method supports decision-making on the economic viability of lithium extraction processes.