Decantation
Encyclopedia
Decantation is a process for the separation of mixtures. This is achieved by carefully pouring a solution from a container in order to leave the precipitate (sediment
s) in the bottom of the original container. Usually a small amount of solution must be left in the container, and care must be taken to prevent a small amount of precipitate from flowing with the solution out of the container. It is generally used to separate a liquid from an insoluble solid (e.g. in red wine
, where the wine is decanted from the potassium bitartrate
crystals). For example, to obtain a sample of clear water from muddy water, muddy water is left in a container until the mud settles, and then the clear water is poured into another container.
A mixture of two immiscible liquid
s can also be separated by decantation. For example, the oil and water extracted from olives may be decanted to obtain the olive oil
. A mixture of kerosene and water can also be separated through decantation.
A centrifuge
may be useful in successfully decanting a solution. The centrifuge causes the precipitate to be forced to the bottom of the container; if the force is high enough, the precipitate may form a compact solid. Then the liquid can be more easily poured away, as the precipitate will likely remain in its compressed form. A mixture of an insoluble solid in liquid is allowed to stand. The solid being insoluble settles at the bottom if kept undisturbed for some time, this process is called sedimentation. The clear liquid is then poured off carefully, this process is called decantation.
Another example of decantation is the regeneration of used chiral stationary phase (CSP). The CSP to be decanted is gently mixed in a container with a compatible solvent to form a suspension. The suspension is allowed to rest for a period of time, after which the supernatant is carefully poured off. The supernatant contains the undesirable constituents of the former suspension, while the leftover sediment in the container is clean, reusable CSP.
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s) in the bottom of the original container. Usually a small amount of solution must be left in the container, and care must be taken to prevent a small amount of precipitate from flowing with the solution out of the container. It is generally used to separate a liquid from an insoluble solid (e.g. in red wine
Wine
Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...
, where the wine is decanted from the potassium bitartrate
Potassium bitartrate
Potassium hydrogen tartrate, also known as Potassium bitartrate, has formula KC4H5O6, is a byproduct of winemaking. In cooking it is known as cream of tartar. It is the potassium acid salt of tartaric acid, a carboxylic acid.-Occurrence:...
crystals). For example, to obtain a sample of clear water from muddy water, muddy water is left in a container until the mud settles, and then the clear water is poured into another container.
A mixture of two immiscible liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
s can also be separated by decantation. For example, the oil and water extracted from olives may be decanted to obtain the olive oil
Olive oil
Olive oil is an oil obtained from the olive , a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps...
. A mixture of kerosene and water can also be separated through decantation.
A centrifuge
Centrifuge
A centrifuge is a piece of equipment, generally driven by an electric motor , that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis...
may be useful in successfully decanting a solution. The centrifuge causes the precipitate to be forced to the bottom of the container; if the force is high enough, the precipitate may form a compact solid. Then the liquid can be more easily poured away, as the precipitate will likely remain in its compressed form. A mixture of an insoluble solid in liquid is allowed to stand. The solid being insoluble settles at the bottom if kept undisturbed for some time, this process is called sedimentation. The clear liquid is then poured off carefully, this process is called decantation.
Another example of decantation is the regeneration of used chiral stationary phase (CSP). The CSP to be decanted is gently mixed in a container with a compatible solvent to form a suspension. The suspension is allowed to rest for a period of time, after which the supernatant is carefully poured off. The supernatant contains the undesirable constituents of the former suspension, while the leftover sediment in the container is clean, reusable CSP.