<unk> , also known as solvent extraction and partitioning, is a method to separate compounds based on their relative solubilities in two different immiscible<unk> s, usually water and an organic solvent. It is an extraction of a substance from one<unk>  phase into another<unk>  phase.<unk>  is a basic technique in chemical laboratories, where it is performed using a separatory funnel. This type of process is commonly performed after a chemical reaction as part of the work-up.
Solvent extraction is used in nuclear reprocessing, ore processing, the production of fine organic compounds, the processing of perfumes and other industries. In an industrial application, this process is done continuously by pumping an organic and aqueous stream into a mixer. This mixes the organic component with the aqueous component and allows ion transfer between them. The mixing continues until equilibrium is reached. Once the ion transfer is complete (equilibrium is reached), the mixture flows into a vessel, where the organic and aqueous are allowed to separate, similar to the way oil and water would separate after mixing them. Fresh material is continuously fed into the mixer, and a two continuous streams is removed from the settler (one organic, and one aqueous). The process is commonly used to process copper and uranium, but has recently been adapted for zinc, at Skorpion Zinc mine in Namibia.<unk>  is possible in non-aqueous systems: in a system consisting of a molten metal in contact with molten salt, metals can be extracted from one phase to the other. This is related to a mercury electrode where a metal can be reduced, the metal will often then dissolve in the mercury to form an amalgam which modifies its electrochemistry greatly. For example it is possible for sodium cations to be reduced at a mercury cathode to form sodium amalgam, while at an inert electrode (such as platinum) the sodium cations are not reduced. Instead water is reduced to hydrogen.
If a detergent or fine solid can stabilise an emulsion which in the solvent extraction community is known as a third phase.
Liquid-liquid extraction
Solid phase extraction
Fractional distillation
Ion chromatography
Freeze drying
Kick chart
Gas diffusion method
Chemiluminescence