What is Decantation?
Definition: Decantation is the
process of separation of liquid from solid and other immiscible (non-mixing)
liquids, by removing the liquid layer at the top from the layer of solid or
liquid below.
Image 1
To put it simply it just means
allowing a mixture of solid and liquid or two immiscible liquids
to settle and separate by gravity. Once the mixture components have
separated, the lighter liquid is poured off leaving the heavier liquid or solid
behind. Typically, a small amount of the lighter liquid is left behind.
In laboratory conditions, small volumes of
mixtures are decanted in test tubes. If time is not a concern, the test tube is
kept at a 45° angle in a test tube rack. This allows the heavier particles to
slide down the side of the test tube while allowing the lighter liquid a path
to rise to the top. If the test tube were held vertically, the heavier mixture
component could block the test tube and not allow the lighter liquid to pass as
it rises.
Sometimes, this process is not very efficient,
for example when separating oil from water as a thin layer of the remaining oil
cannot be easily procured from the mixture. In order to make the procurement
easier and the separation efficient, we use a separating funnel, as shown in
the next figure
Image 2
So... for what purpose is this method
used?
Well,
the purpose may be either to produce a clean decant or to remove undesired
liquid from the precipitate (or other layers). If the aim is to produce a clean
solution, a small amount of solution must generally be left in the container,
and care must be taken to prevent any precipitate from flowing with the
solution out of the container.
Examples of
mixture that can be decanted
1)
Wine - Well if you’ve heard of decantation before it’s probably from
decantations of wine right? Wine is decanted to separate the wine from
sediments. The wine is poured, and solids stay in the base of the decanter. In
the case of wine, the solid is usually potassium bitartrate crystals.
2)
Dirt and water – Muddy water can be cleared by decanting. The soil will sink to
the bottom of the tube allowing the clear water to be poured off.
3)
Cream and milk – Cream is separated from milk by decantation. Cream rises to
the top of the milk mixture and is easily skimmed off.
4)
Blood and plasma – A centrifuge is necessary for this decantation. Plasma can
be removed from blood by decantation.
Below is a simple
demonstration of the decantation process
Video 1
Thank you for your time reading this article. I
hope you are blessed today :D
References
Video
1, Smartcircuits Innovation, (June 19, 2017). Retrieved October 10, 2019,
from https://www.youtube.com/watch?v=P23Sk5CwZ9Y
Image
1, Byjus App. Retrieved October 10, 2019, from https://cdn1.byjus.com/wp-content/uploads/2016/06/Decantation-Definition.png
Image
2, Byjus App. Retrieved October 10, 2019, from https://cdn1.byjus.com/wp-content/uploads/2016/06/Decantation-Definition2.png
Decantation,
Wikipedia, (November 1, 2016). Retrieved October 10, 2019, from https://en.wikipedia.org/wiki/Decantation?oldid=747277503
Separation
by Decantation and Loading. Retrieved October 10, 2019, from https://byjus.com/chemistry/decantation
Helmesntine, Todd. "Decantation Definition in Chemistry.", ThoughtCo, (2019, October 6). Retrieved
October 10, 2019, from https://www.thoughtco.com/decantation-in-chemistry-609185
Helmesntine, Anne Marie, Ph.D. "What Is Decantation and How Does It Work"?, ThoughtCo, (2019, May 21). Retrieved October 10,
2019, from https://www.thoughtco.com/definition-of-decantation-604990
