Steam distillation and azeotropic distillation are separation processes. Steam distillation uses steam to distill temperature sensitive compounds like essential oils at lower temperatures to prevent decomposition. It produces a mixture of water and organic distillate that can be separated. Azeotropic distillation uses an entrainer added to the original mixture to form a new azeotrope that distills off, allowing separation of the original components which could not be separated otherwise due to forming an azeotrope. Both processes exploit differences in volatility between mixture components to achieve separation.

1. PRESENTATION ON THE TOPIC:
STEAM DISTILLATION AND
AZEOTROPIC DISTILLATION
SUBMITTED BY-
TUTUMONI KALITA
M.PHARM, 2nd sem

2. Definition-
• Distillation is the process of separating the
components or substances from a liquid mixture by
using selective boiling and condensation.
• Distillation may result in essentially complete
separation (nearly pure components), or it may be a
partial separation that increases the concentration of
selected components in the mixture. In either case,
the process exploits differences in the volatility of
the mixture's components.
• In industrial chemistry, distillation is a unit
operation of practically universal importance, but it
is a physical separation process, not a chemical
reaction.

3. Steam distillation
• Steam distillation is a special type of distillation
(a separation process) for temperature
sensitive materials like natural aromatic compounds.
• It once was a popular laboratory method for
purification of organic compounds, but has become
less common due to the proliferation of vacuum
distillation. Steam distillation remains important in
certain industries.
• This process effectively enables distillation at lower
temperatures, reducing the deterioration of the
desired products. If the substances to be distilled are

4. very sensitive to heat, steam distillation may be
applied under reduced pressure, thereby reducing the
operating temperature further.
• After distillation the vapours are condensed. Usually
the immediate product is a two-phase system of
water and the organic distillate, allowing separation
of the components by decantation, partitioning or
other suitable methods.

5. Principle-
 When a mixture of two
practically immiscible liquids is heated while being
agitated to expose the surface of each liquid to the
vapour phase, each constituent independently exerts
its own vapour pressure as a function of temperature
as if the other constituent were not present.
 Consequently, the vapour pressure of the whole
system increases. Boiling begins when the sum of
the vapour pressures of the two immiscible liquids
just exceeds the atmospheric
pressure (approximately 101 kPa at sea level). In
this way, many organic compounds insoluble in
water can be purified at a temperature well below
the point at which decomposition occurs.

6.  For example, the boiling point
of bromobenzene is 156 °C and the boiling point of
water is 100 °C, but a mixture of the two boils at
95 °C. Thus, bromobenzene can be easily distilled at
a temperature 61 °C below its normal boiling point.

7. Apparatus-

8. Applications-
• It is employed in the manufacture of essential oils,
for use in perfumes for example. In this method,
steam is passed through plant material containing
desired oils.
• Eucalyptus oil and orange oil are obtained by this
ethod in the industrial scale.
• Steam distillation is also used to separate
intermediate or final products during synthesis of
complex organic compounds.
• Also widely used in petroleum refineries and
petrochemical plants.

9. AZEOTROPIC DISTILLATION
Azeotropic mixture-
• An azeotrope is a mixture of two or more liquids
in such a ratio that its composition cannot be
changed by simple distillation. This occurs because,
when an azeotrope is boiled, the resulting vapour
has the same ratio of constituents as the original
mixture.
• Because their composition is unchanged by
distillation, azeotropes are also called constant
boiling mixtures.

10. Positive and negative azeotropes-
• Each azeotrope has a characteristic boiling point. The
boiling point of an azeotrope is either less than the
boiling point temperatures of any of its constituents (a
positive azeotrope), or greater than the boiling point of
any of its constituents (a negative azeotrope).
• A well-known example of a positive azeotrope is
95.63% ethanol and 4.37% water (by mass) boils at
78.2 °C. Ethanol boils at 78.4 °C, water boils at 100 °C,
but the azeotrope boils at 78.2 °C, which is lower than
either of its constituents. Indeed, 78.2 °C is the
minimum temperature at which any ethanol/water
solution can boil at atmospheric pressure. Positive
azeotropes are also called minimum boiling
mixtures or pressure maximum azeotropes.

11. • In general, a negative azeotrope boils at a higher
temperature than any other ratio of its constituents.
Negative azeotropes are also called maximum
boiling mixtures or pressure minimum azeotropes.
An example of a negative azeotrope is hydrochloric
acid at a concentration of 20.2% and 79.8% water
(by mass). Hydrogen chloride boils at −84 °C and
water at 100 °C, but the azeotrope boils at 110 °C,
which is higher than either of its constituents. The
maximum temperature at which any hydrochloric
acid solution can boil is 110 °C.

12. Principle:
• It involves the addition of a new component called
the entrainer, to the original feed mixture to form an
azeotrope with one or more of the feed components.
• The azeotrope is then removed as either the distillate
or the bottoms.
• The new component is added to the feed mixture to
break the azeotrope that otherwise would be formed
by feed components.

17. THANKYOU!