LC centrifugal solvent extraction technology achieves phase separation in a centrifugal field, resulting in a high separation factor. This unique combination of properties and advantages distinguishes centrifugal extraction from other gravity-based phase separation systems, including high extraction efficiency, low fraction retention, excellent mass transfer, short residence time, minimal footprint, and ease of fully automated process control. Currently, it is widely used in industries such as hydrometallurgy, APIs, biopharmaceuticals, pesticides, and food. Applications include extracting rare and precious metals such as nickel, cobalt, copper, gold, silver, scandium, francium, uranium, thorium, rhenium, and zinc; extracting phosphoric acid and oils; classifying organic compounds; separating multi-component mixtures; extracting traditional Chinese medicines, chemical drugs, veterinary drugs (including feed additives); APIs; tea polyphenols, sucralose, lactic acid, citric acid; and phenolic and metal wastewater.

The choice of extractant is crucial in LC centrifugal solvent extraction. In engineering applications, the selection of extractants requires a key consideration of the distribution coefficient, that is, the distribution ratio of the target substance in the extractant must be much higher than that in the aqueous phase (usually >10); physical property differences must also be considered, that is, the density difference between the extractant and the aqueous phase must be >0.05 g/cm³ (for example, the density of kerosene is 0.8 g/cm³, and the density of the aqueous phase is 1.0 g/cm³), which is more conducive to centrifugal separation.

How To Choose Extractant For Copper, Nickel, Cobalt, Lithium etc. Metal Solvent Extraction?

A lot of practice has proved that the selection of extraction agent follows the following 9S principle

1. Selectivity

The extractant should have high selectivity for the target solute, meaning it preferentially extracts the target substance while having a weaker extraction ability for other impurities. This improves extraction efficiency and product purity. For example, when extracting a specific metal ion from a solution containing multiple metal ions, the selected extractant should have a strong complexing or affinity for the target metal ion, with no or weaker effects on other metal ions.
Solubility
The extractant should have high solubility in the organic phase to ensure uniform distribution and form a stable extraction system. At the same time, its solubility in the aqueous phase should be as low as possible to minimize solvent loss in the aqueous phase, thereby improving its utilization and economic efficiency. Common organic solvents such as dichloromethane and chloroform have good solubility for many organic solutes but low solubility in water.

2. Stability

The extractant should have good chemical and thermal stability. During the extraction process, it should not react chemically with other substances in the extraction system and should not decompose or deteriorate under high temperatures, acidic or alkaline conditions, or other conditions. This helps ensure the reproducibility and reliability of the extraction process and prolongs the life of the extractant. For example, some phosphorus-containing extractants exhibit good stability under acidic conditions and can be used for metal extraction in acidic systems.

3. Separation

After extraction, the organic phase containing the extractant and the raffinate (aqueous phase) should separate quickly and clearly to facilitate phase separation. Good phase separation can improve extraction efficiency, reduce phase carryover, and prevent product contamination. For example, by selecting an appropriate extractant and adjusting extraction conditions, physical properties such as the density difference and interfacial tension between the organic and aqueous phases can be optimized for rapid phase separation.

4. Safety
Extractants should have low toxicity, corrosiveness, and flammability to ensure production safety. Selecting safe extractants can reduce hazards to the environment and human health, lowering safety risks and environmental costs. Non-toxic or low-toxic extractants, such as green extractants and ionic liquids, are preferred.

5. Speed of Extraction
The extractant should react rapidly with the target solute, allowing the extraction process to reach equilibrium quickly, thereby improving production efficiency. A fast extraction speed can reduce equipment residence time and volume, lowering investment costs. For example, certain extractants containing specific functional groups react quickly with the target substance, enabling the extraction process to be completed instantly.

6. Source
The extractant should be sourced from a wide range of sources, with a stable supply and reasonable pricing. This helps ensure continuous and economical production and reduce costs.

7. Specificity
In certain extraction processes, the extractant needs to have specific recognition and extraction capabilities for the target substance, specifically targeting a specific type or class of substances with a specific structure. This specificity improves extraction precision and selectivity, enabling the separation and purification of specific substances in complex systems. For example, crown ether extractants exhibit unique selectivity and specificity for alkali metal ions, making them useful for selectively extracting specific alkali metal ions from mixed ion solutions.

8. Synergism
When using a mixed extraction system composed of multiple extractants, the extractants should exhibit good synergistic effects, promoting each other and improving extraction efficiency and selectivity. This synergistic effect can enhance the performance of the mixed extractant compared to a single extractant, resulting in more efficient extraction and separation. For example, in some metal extraction systems, the combination of different extractants creates a synergistic effect through hydrogen bonding, complexation, and other interactions, significantly enhancing the extraction of the target metal ion.

LC centrifugal solvent extraction technology is increasingly being used in industrial production. Going forward, CTX centrifugal solvent extraction technology will continue to adhere to the principles of high efficiency, green development, and low carbon emissions. We will research new solvent extraction processes, develop efficient and green extraction agents, and develop high-performance, high-reliability extraction equipment to better serve industrial needs.