Liquid Liquid Extraction

What is Liquid Liquid Extraction (LLE)?

Liquid-Liquid Extraction, or liquid liquid separation, is the removal of a soluble constituent from one liquid by means of transferring it to another. 

Why Use Liquid-Liquid Extraction?

The reasons behind using an extraction process such as liquid-liquid separation vary, but you may consider this process when: 

  • The material is heat sensitive
  • The material is non-volatile
  • Distillation isn't feasible due to the materials having similar boiling points, poor relative volatilities, or the formation of azetropes
  • Breaking azetropes

Liquid Liquid Extraction vs. Distillation

Distillation uses the different boiling points/volatilities of the components. If the components have similar boiling points or volatilities, or they are heat sensitive, extraction will work better. Sometimes distillation will require complex sequences, high investments, high energy costs, and high operating costs due to the phase change of the components.

Which Industries Use LLE?

  • Food & Beverage - mainly for flavoring
  • Pharmaceuticals
  • Specialty Chemicals
  • Mining
  • Hydrometallurgy
  • and more!

How Do Extractors for LLE Work?

Inside the Pod Extractor are concentric perforated bands. Heavy liquid is introduced inboard and flows outward. Light liquid is introduced outboard and flows inward. The intimate contact that occurs as these liquids make their journey counter-currently results in the transfer of mass and/or components from one liquid to the other. This is the general method for all extractors used in liquid-liquid extraction. A single united can provide 3-5 theoretical stages of extraction.