Decantation and centrifugal separation process

1. Decantation and Centrifugal Separation

2. Contain
INTRODUCTION
DECANTATION SEPARATION
CENTRIFUGAL SEPARATION
DIFFERENCE
IMPORTANT TIP
1.
2.
3.
4.
5.

3. Introduction of Separation
 A separation process is a method that converts a mixture or a solution of chemical
substances into two or more distinct product mixture.
 In some cases, a separation may fully divide the mixture into pure constituents.
 Separations exploit differences in chemical properties or physical properties (such as
size, shape, mass, density, or chemical affinity) between the constituents of a mixture.
 In this presentation we talking about two separation method;
1. Decantation Separation
2. Centrifugal Separation

4. Decantation Separation
 Decantation is a process that separates components of a mixture based on differences in
density.
 Decantation involve two steps:
1. Sedimentation: Sedimentation uses gravity or a centrifuge to separate mixture components
based on density.
2. Decanting: Decanting is pouring or siphoning off the top component of a mixture or daring the
bottom component.
Theory

5. What is Decantation?
 Decantation is a process for the separation of mixture of mixtures of immiscible liquids or
of a liquid and a solid mixture such as a suspension.
 An incomplete separation is witnessed during the separation of two immiscible liquids,
Working Principle
 The basic principle of decantation is the heavier (denser) substances sink, while lighter
(less dense) substances float.
 In its simplest form, decantation uses gravity to separate a solid and liquid or two
immiscible liquids.
 The lighter component is poured or siphoned off the top of the mixture.

6. Uses of decantation
 Decantation can be used to separate immiscible liquids that have different densities.
 For example, when a mixture of water and oil is present in a beaker, a distinct layer
between the two consistency is formed, with the oil layer floating on top of the water
layer.
Common example
1. Oil and Vinegar
2. Oil and Water
3. Kerosene and water
Equipment

7. Oil floats on top of water. After letting a mixture of oil and
water sit, the oil can be poured off of the water. In a separatory
funnel, the water can be drained away from the oil.
Decantation is one way to clean muddy water. Soil and debris
sinks to the bottom, so clear water is poured off. Decanting
water isn’t sufficient to completely purify it because some
particles (like bacteria and viruses) are too light to sink with the
dirt. Other particles dissolve in water (like heavy metals and
pesticides). Even after decantation, other method are needed
to produce drinking water, like filtration or distillation.
The kerosene or gasoline floats above the water. Decanting this
liquid is dangerous because the fuel evaporates to from
flammable, toxic fumes.
Decantation separates cream from milk. Cream rises to the
liquid and is easily skimmed off.
Examples

8. Centrifugal Separation
 Centrifugation is the process that uses centrifugal force for the separation of two liquids
in a mixture.
 In this process, the denser component of the mixture migrates away from the axis and
the lighter component migrates towards the axis.
 Example : Let us understand this process with the example of milk are rotated, the
heavier milk is pulled outward against the wall, whereas, the lighter cream is collected in
the middle. Both the components are then collected separately.
Theory

9. Working Principle
 A centrifuge operates by using the sedimentation principle: liquids separate according to
their density under the influence of gravitational force (g-force).
 Various forms of separation, including isopycnic, ultrafiltration, gradient of mass, phase
separation, and pelleting, are known.
Types of Centrifugation
 For splitting ions, there are two types of centrifugal techniques;
1. Differential centrifugation
2. Centrifugation of density gradients
 It is further possible to separate density gradient centrifugation into rate-zonal and
isopycnic centrifugation.

10. Centrifuge
 A centrifuge is a system that separate the component parts of a liquid or fluid (and even
gases) using centrifugal force.
 This is done b rotating the fluid in a bottle at high speed, thereby separating fluids of
varying densities (e.g. milk cream) or liquids from solids.
Uses of centrifuge
 A centrifuge is a laboratory instrument that is used, depending on mass, to isolate gases,
gas or liquid.
 By rotating a vessel carrying material at high speed, separation is accomplished; the
centrifugal force forces heavier materials to the outside of the vessel.
Low speed High speed Ultra speed

11. Centrifugation
separation of solid substances
from highly concentrated
suspensions
Separation of oily concentrated
sludge
Separation of oily suspensions
Separation of heavy particles and
large sized grains by cycloning
Main Applications

12. Difference
Decantation
 Decanting allows two immiscible
liquids of a mixture of solid and
liquid to separate out by gravity.
 Once the mixture components
have separated, the lighter liquid is
poured off leaving the heavier
behind.
 It is not very accurate as a small
amount of the lighter is always left
behind.
Centrifugation
 In a centrifugation is the process
that used centrifugal force to
separate various component of
fluid.
 A centrifuge is used to spin
mixtures of solids and liquids very
fast so that the solid gravitates the
bottom and the liquid to the top.

13.  For a more accurate method of purification,
centrifugation and decantation are used
together; you use the centrifuge to separate
the solid and the liquid then decant the liquid
off the top, however a small amount of the
liquid is always left behind.
Important for this topic