卤水中的锂
AN-T-181
2020-05
zh
Reliable and inexpensive determination by potentiometric titration
锂是一种软金属，可用于多种用途，如生产高温润滑剂或耐热玻璃。此外，锂还大量用于电池生产。锂是从卤水和高品位锂矿石中提取的。本应用说明展示了一种通过电位滴定法确定盐水中锂浓度的方法。锂和氟化物在乙醇中沉淀为不溶性氟化锂。使用氟化铵作为滴定剂和氟离子选择电极 (ISE)，可以通过电位滴定法进行测定。与使用原子吸收光谱（AAS）等其他更复杂的技术测定盐水中的锂相比，这种方法更靠谱靠、更快速、成本更低。
Lithium is a soft metal which is used for many applications, such as production of high-temperature lubricants or heat-resistant glass. Furthermore, lithium is used in large quantities for battery production. It is obtained from brines and high-grade lithium ores. Depending on the lithium concentration, extraction may or may not be economically viable.
This Application Note demonstrates a method to determine the lithium concentration in brines by potentiometric titration. Lithium and fluoride precipitate in ethanol as insoluble lithium fluoride. Using ammonium fluoride as titrant and a fluoride ion selective electrode (ISE), determination of lithium via potentiometric titration is possible.
This method is more reliable, faster, and less expensive than the determination of lithium in brine by other more sophisticated techniques such as atomic absorption spectroscopy (AAS).
Two samples with ~20% (m/m) and ~40% (m/m) lithium chloride are analyzed. No further sample preparation is required.
The analysis is carried out with an automated system consisting of tiamoTM in combination with a 905 Titrando. A fluoride ion selective electrode (ISE) in combination with a Long Life ISE reference electrode is used for the indication of the titration.
After transferring an appropriate amount of sample into the titration vessel, enough ethanol is added to cover the diaphragm of the electrode. The titration is carried out using ammonium fluoride until after the first equivalence point is reached.
Calcium will interfere with the analysis and has to be analyzed separately.
For both samples this method gave reliable and reproducible results.
| n = 3 | Assay of LiCl brine 1 in % | Assay of LiCl in brine 2 in % |
|---|---|---|
| Mean | 41.3 | 14.85 |
| SD(abs) | 0.7 | 0.11 |
| SD(rel) | 1.6 | 0.7 |
Using ethanol as solvent, ammonium fluoride as titrant, and the fluoride ISE for indication, the determination of lithium in brine can be performed reliably and cost-efficiently.
Therefore, this method provides an inexpensive and simple approach to determine if an extraction of lithium from brine is economically feasible or not.
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