The document provides an extensive overview of distillation, including its history, principles, terminology, assembly components, and various methods such as simple, flash, vacuum, and steam distillation. Distillation is defined as the process of separating liquid mixtures through vaporization and condensation to obtain pure components. Applications of these methods are addressed across industrial contexts, highlighting their significance in the pharmaceutical and oil refining industries.

1. DISTILLATION
Prepared by,
Nilam Kaushikbhai Mistry
2nd Semester, M.Pharm - PCH
Pharmaceutical Process Chemistry
Enrollment No: 190821212003
1

2. Contents:
1. Introduction
2. Terminology
3. Principle
4. Distillation assembly
5. Classification
6. Steam distillation
7. Azeotropic distillation
8. Application
2

3. Introduction:
 Distillation is a separation of a two or more
components of a liquid mixtures by process
of partial vaporization and subsequent
condensation to recover two or more of the
components in a nearly pure state.(1)
OR
 Distillation is the process of separating the
components or substances from a liquid
mixture by selective boiling and
condensation.(2)
3

4. History(3,4)
 The earliest evidence of distillation comes
from a terracotta distillation apparatus dating
to 3000 BC in the Indus valley of Pakistan.
 Distillation was known to be used by the
Babylonians of Mesopotamia around
1200BC.
 Initially, distillation is believed to have been
used to make perfumes.
 The Arab chemist Al-Kindi distilled alcohol in
9th century Iraq.
 Distillation of alcoholic beverages appears
common in Italy and China starting in the
12th century.
4

5. a) Still of Democritos, also called the alembic of Synesios, which originally
meant kettle, in which water was boiled , fourth century
b) A distillation plant in Damascus consisting of multiple units for producing
rose water, thirteenth century.
•This apparatus was
originated from the
Alexandrian philosophy
schools in the first
centuries AD 100 to
900, which overlaps
with the Arabian period
(AD 700 to 1600).
•The apparatus consists
of four elements:
(1)head (helmet
dalembicum),
(2)receiver (vessel
drecaptaculum),
(3)still
(4) sand bath or water
bath on a tripod.
5

6. Terminology(5)
 Binary mixture: When two liquids mixed together, they may be miscible
with each other in all proportion, such miscible liquid are known as binary
mixtures of liquid.
Example:
1. Ethanol + Water
2. Acetone + Water
 Ideal Solution: The one in which there is no change in the properties of
components other than dilution, when they mixed to form a solution.
Properties:
1. Total volume of solution is equal to sum of volume of each
component.
2. No heat absorbed and evolved.
3. No change in reaction in-between.
4. Follow Raoult’s law
Example: Benzene and toluene
6

7.  Real Solution: Most system shows varying degree of deviation from
raoult’s law, depending on nature of liquids and temperature. These
solution are known as real solutions.
Properties:
1. Heat may absorbed or evolved
2. Chemical reaction occur in-between
3. Don’t follow raoult’s law
Example: Acetone and Chloroform
 Volatility: any substance in solution may be defined as the equilibrium
partial pressure of substance in vapour phase divided by the mole
fraction of substance in the solution.
Example: substance A in a liquid mixture has partial pressure PA and
its concentration in the mixture is XA on mole fraction scale.
Volatility of compo. A = Partial vapour pressure of A
Mole fraction XA of A in solution
VA = PA/XA
The volatility of a material in the pure state is equal to the vapour
pressure of the material.
7

8.  Relative volatility(α): Consider a liquid mixture
containing two component A and B, In such case, the
volatility of one component is expressed in terms of
second as below,
α = Volatility of compo. A(VA)
Volatility of compo. B(VB)
 Vapour pressure: The pressure exerted by vapor in
thermodynamic equilibrium( transformation of matter
and energy in systems as they approach equilibrium)
with its condensed phases (solid or liquid) at a given
temperature in a closed system.
 Azeotropic mixture: Mixture of special composition
given minimum OR maximum boiling point
respectively.
8

9. Principle(1,6)
 The principles are referred by VAPOR–LIQUID EQUILIBRIUM DIAGRAM. The
diagram relates to a binary mixture containing components P and Q.
 The lower curve gives the composition of the liquid boiling at various
temperatures whilst the upper curve gives the composition of the vapor in
equilibrium with the boiling liquid.
 Points x and y, therefore, give the boiling points of the individual components P
and Q, respectively.
 For example, point A shows that at X degrees the vapor has a composition of
approximately 90% P, whilst point B shows that the boiling liquid with which it is
in equilibrium has a composition of approximately 80% P. In a continuous
distillation process, such as occurs in a distillation column, liquid of composition
C (90% Q, 10% P) vaporizes to vapor of composition D, which condenses to
liquid of composition E. Subsequently, liquid E becomes vapor F and liquid G
(composition: 50% Q, 50% P).
 This continuous process of vaporization and condensation occurs in the
distillation column until a volatile fraction leaves the top of the column and is
removed from the process by being collected in the collection flask.
 At the same time the liquid in the distillation flask becomes progressively more
concentrated in the involatile component.
9

10. 10

11. Raoult’s Law(6,8):
 It express a quantitative relationship between the concentration and
vapour pressure.
 It states that partial vapour pressure of each volatile constituent is
equal to vapour pressure of the pure constituent multiplied by its mole
fraction in the solution at a given temperature.
 Suppose Homogeneous mixture of liquid A and B
Partial vapour pressure of component A in mixture PA = P ̊A * XA…1
Mole fraction of A in solution = XA
Vapour pressure of A in pure state = P ̊A
Partial vapour pressure of component B in mixture PB = P ̊B * XB
Mole fraction of B in solution XB = (1 – XA)
Vapour pressure of B in pure state = P ̊B
 Total vapour pressure of mixture PT = PA + PB
PT = P ̊A * XA + P ̊B * XB
11

12. 12

13.  In addition as per Dalton's law
PA = YA * PT
Molecular fraction of A in vapour = YA
YA = PA = PA
PA +PB PT
= P ̊A * XA = P ̊A * XA
P ̊A * XA + P ̊B * XB PT
YB = P ̊B * XB
PT
Now , YA + YB =1
P ̊A * XA + P ̊B (1 – XA) = 1
PT PT
XA= PT - P ̊B
P ̊A - P ̊B
13

14. Limitation of Raoult’s law
 For some pairs of liquids this law holds quite well for all
concentrations, e.g.. Pentane and heptane, benzene
and chlorobenzene. In other cases such as
hydrochloric acid and water, alcohol and water it
doesn’t hold at all.
 It applies only to mixtures in which the components are
very similar chemically and the molecules of the two
substance do not interact in any way.
 Raoult’s law applies to many systems which states that
is applies to the solvent(pure component) and is only
valid to short range of compositions and composition
rich in solvent(dilute solvent).
14

15. POSITIVE DEVIATION
•In some liquids systems, the total
vapour pressure is greater than the
sum of the partial pressures of the
individual component
•Example: benzene and ethanol
•Differ in their polarity, length of
hydrocarbon chain and degree of
association.
NEGATIVE DEVIATION
•In some liquids systems, the total
vapour pressure is lower than the
sum of the partial pressures of the
individual component
•Example: chloroform and acetone
•Due to hydrogen bonding, salt
formation and hydration.
15

16. Henry’s law(1,9)
It is states that the partial pressure of liquid (solute) mixed in large amount of
solvent is proportional to its mole fraction in the solution.
PA α XA
Partial pressure of component A over liquid mixture PA = HXA….2
Mole fraction of A = XA
Henry’s law constant = H
Now, Compare Raoult’s law 1 equation and Henry’s law 2 equation
YA = PA OR H * XA
PT PT
YA= H’XA Where H’ = H
PT
Also written as H = c
pA
Where c = concentration in a liquid as pound mols per cubic foot
pA = partial pressure of the solute in atmospheres.
16

17. Distillation Assembly(1)
17

18.  STILL:
• It is a vaporizing chamber and used to place the material to be
distilled.
• The still is heated by a suitable means of vaporization of the volatile
constituents.
• On laboratory scale RBF ( round bottom flask ) made of glass are
used so that the progress of the distillation can be noticed.
• A condenser is attached to the still using appropriate joints.
• A trap is inserted between distillation flask and condenser.
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19.  CONDENSER:
• Used to condense the vapor.
• It is kept cold by circulating water/air through jacket.
TYPES
 Single surface condensers
 Straight tube
 Bulb type
 Spiral
 Coiled type
 Double surface condensers
 Multi – tubular condensers
19

20. 20

21.  RECEIVER:
• It is used to collect distillate.
• It may be simple flask.
• It immersed in ice-bath to minimize loss of volatile matter.
• Florentine receivers are used for the separation of oil and
water.
TYPES:
 Type-1 : For separation of oil heavier than water.
 Type-2 : For separation of oil lighter than water
21

22. RECEIVERS
22

23. Classification(1,10):
 Simple distillation
 Flash distillation
 Vacuum distillation
 Molecular distillation
 Fractional distillation
 Destructive distillation
 Compression distillation
 Steam distillation
 Aezotropic distillation
23

24. 1. SIMPLE DISTILLATION:
Principle: liquid boils
when its vapour pressure
is equal to atmospheric
pressure. Is conducted
at its BP. The higher the
relative volatility of a
liquid, the better is the
separation by these
distillation. Heat is
supplied to liquid so that
it boils. The resulting
vapour is transferred to
different place and
condensed.
Application:
•Used for preparation of distilled water and water injection.
•Volatile and aromatic waters are prepared.
•Organic solvents are purified.
•Non volatile solids are separated from volatile liquids.
24

25. 2. FLASH DISTILLATION:
Principle: When a hot
liquid mixture is allowed
to enter from a high
pressure zone into a low
pressure zone, the entire
liquid mixture is suddenly
vaporized which is known
as flash vaporization .
During these chamber
gets cooled. The
individual vapour phase
molecules of high boiling
fraction get condensed,
while low boiling fraction
remains as vapour.
Application:
•Used for separating components, which boil at widely different temperatures.
•Used in petroleum industry for refining crude oil.
25

26. 3.VACCUME DISTILLATION:
Principle: Liquid boils
when vapour pressure
is equal to
atmospheric pressure,
i.e., pressure on its
surface. If the external
pressure is reduced by
applying vacuum, the
boiling point of liquid is
lowered. This principle
is illustrated using an
example of water.
The net result is the
increase in rate of
mass transferred into
vapourApplication:
•Preventing degradation of active constituents
•Enzymes – malt extract, pancreatin
•Vitamins – thiamine, ascorbic acid
•Glycosides – anthraquinones 26

27. 4. MOLECULAR DISTILLATION:
Principle: The substance
to be distilled have very
low vapour pressure.
E.g., viscous liquids, oils,
greases, waxy materials
and high molecular
weight substances.
The pressure exerted by
vapors above the liquid is
much lower. At very low
pressure, the distance
between the evaporating
surface and the
condenser is
approximately equal to
the mean free path of the
vapour molecules.
Application:
•Used in the refining of mixed oils.
•Free fatty acids are distilled at 100 ̊C.
•Vitamin A is separated from fish liver oil.
27

28. 5.FRACTIONAL DISTILLATION:
Principle: When a
liquid mixture is
distilled, the partial
condensation of the
vapour is allowed to
occur in a
fractionating column.
In the column,
ascending vapour
from the still is
allowed to come in
contact with the
condensing vapour
returning to the still.
This results in
enrichment of the
vapour with the more
volatile component.
Application:
•Used for the separation of volatile miscible liquids
with near BP such as a
1. Acetone and water.
2. Chloroform and benzene
28

29.  Distillation is decomposition product of constituents
of the organic matter burnet in absence of air.
 Not used in lab practice but very useful in industrial
process to obtain valuable product from wood, coal
and animal matter.
 It involve the heating of dry organic matter in suitable
vessel in absence of air, until all volatile substances
are driven off.
 The distillate is the decomposition product of
constituents.
 Wood distillation industry and coal caronation
industry provides many useful fuel material with the
method.
6. DESTRUCTIVE DISTILLATION:
29

30.  Compression distillation method was developed to meet
the need of navy and army for fresh water from sea-
water.
 Product obtained is quite pure and pyrogen-free, there for
it meets the requirement of Pharmaceutical industry.
 Its economical from the standpoint of consumption of fuel
and water.
 The feed water is heated in an evaporator for boiling then
a vapour gets separate and conveyed to compressor
which raises its temperature to about 118 ̊ C
 It than flows to the steam chest where its condensed on
the outer surface of tube.
 During condensation, heat is released which is allowed
for heating of fresh feed in the tube.
7.COMPRESSION DISTILLATION:
30

31.  STEAM DISTILLATION:
31

32. Steam distillation of volatile oils (1)
32

33.  Steam distillation is method of distillation carried out
with aid of steam.
 It is used to separate..
- high boiling substance from non-volatile impurities.
- separate immiscible liquids.
Examples:
Boiling point of turpentine = 160 ̊ C
Boiling point of water + turpentine mixture = 95.6 ̊ C
At these temperature vapour pressure of
Water = 86.245 kPa
Turpentine = 15.06 kPa
Sum of vapour pressure = 101.31 kPa
Which is normal atmospheric Pressure and thus high
boiling liquid may be distilled with water at a
temperature much below its BP.
33

34.  Principle: A mixture of immiscible liquid begins to
boil when sum of their vapour pressure is equal to
atmospheric pressure.
In case of mixture of water and turpentine, mixture
boils below the BP of pure water, though turpentine
boils at a much higher temperature than that of
water.
 Application:
• Used to separate immiscible liquids.
E.g., water + toluene
• To extract volatile oils like clove, anise and
eucalyptus oils
• Purification of essential oils like a almond oil.
• Camphor is distilled by these method.
• Aromatic water are prepared.
• Recovery of aniline from the reducer charge.
34

35.  Construction:
• Metallic still can fitted with cork having two
holes.
• Safety tube inserted up to bottom through
one hole to maintain pressure in side steam
can, more over when steam comes out from
safety tube indicates that can is empty.
• Through other hole band tube is passed and
other end of this tube is dipped.
• Flask and condenser is connected with
delivery tube.
• Condenser is connected is receiver with help
of adopter.
35

36.  Working:
• Metallic steam can fitted with cock having two holes.
• Safety tube inserted up to bottom through one hole
to maintain pressure in side stem can, more over
when steam comes out from safety tube indicates
that can is empty.
• Through other hole band tube is passed and other
end of this tube is connected to flask containing non-
aqueous liquid in which tube is dipped.
• Flask and condenser is connected with delivery tube.
• Condenser is connected to receiver with help of
adopter.
• Provision are made to heat both steam and flask
separately
36

37.  Advantages:
• Steam distillation is used for thermo labile
material as higher BP component boil below
100 C
 Disadvantages:
• Product is mixture of water and non-aqueous
liquid, cannot separate completely.
 Limitation:
• Not suitable when two immiscible liquids react with
each other.
37

38. Azeotropic distillation(5)
38

39. 39

40.  Azeotropic distillation: Its volatility
characteristics are always such that it forms
one or more azeotropes, usually of the
minimum boiling type, with the components
of the system called azeotropic distillation.
 An entrainer that forms a heterogeneous
azeotrope with one of the original
component is advantageous because the
recovery of the azeotrope former requires
less equipment.
Example: Use of benzene for dehydrating
ethanol-water mixture.
40

41.  A continuous azeotropic distillation unit for dehydrating alcohol-water
azeotrope is shown in figure.
 The azeotrope is fed to column A. the required quantity of benzene is
added to the feed. The vapour from column A, which approaches the
ternary azeotrope in composition, when cooled to atmospheric
temperature separates into a benzene phase and a water phase .
 These are separated in a decanter. The benzene phase is returned to
the main column as a reflux and to serve as the entrainer and the
water phase is fed to column B in which the benzene is recovered as
the ternary azeotrope which is returned to column A.
 Aqueous alcohol from the base of column B is fed to a column C.
 The overhead from this column, which is 96 % alcohol, is recycled to
the main column for dehydration, and practically pure water is
discarded from the base of the column.
 Anhydrous alcohol is taken out as the residue from the main column
A. since benzene is cycled continuously back to column A.
 Trichloroethylene, BP 87.2 ̊C can be employed as the entrainer
instead of benzene.
41

42. Dehydration of 96% alcohol to absolute alcohol by azeotropic distillation with
benzene.
42

43. Application(1,3)
 Separation of volatile oils.
 Separation of drugs from plant and animal source.
 Purification of organic solvent.
 Manufacture of official preparations.
 Quality control methods.
 Refining of petroleum products.
 Recovery of solvents.
 Purification of drugs obtained from chemical process.
 Production of gasoline, distilled water, xylene, alcohol,
paraffin.
 Gas like nitrogen, oxygen, and argon are distilled from air.
 For making food flavorings
 Used in perfume industries
43

44. Reference:
1. Girish.K.Jani , H.G.Jani et al., Pharmaceutics -1 by B.S.Shah prakashan, page
no: 243-364.
2. Roger Ruan, Yaning Zhang, and Paul Chen et al., Biofuel: introduction,
biochemical(2019), page no: 3-43.
3. Anne marie helmenstine et al.,chemistry journal (2019) page no: 1- 5
4. Norbert Kockmann et al., history of distilation chemistry (2014), page no: 1-10
5. K. Sambhumurthy et al.,Pharmaceutical engineering by new age international
limited, publishers, page no: 126-172
6. J.D.Green, encylopedia of anlytical science (2005), page no: 281-285.
7. Ahmead.Y et al., Science and technology in islam (2001),page no: 65-69.
8. J.F.Richardson, J.H.Harker et al., chemical engineering series vol -2 (2002),
page no: 542-655.
9. A.Kayode Cokar et al., chemistry journal vol -2 (2010), page no: 1-268.
10. Wilfred l.F. Armando et al., 7th edition chemistry (2013), page no: 1-70.
44

45. 11. Zeki Berk Professor et al., by food process engineering and technology 2nd
edition (2013), page no : 329-352.
12. Sue Clarke et al., by essential chemistry for aromatheraphy 2nd edition (2008) ,
page no: 79-93.
13. Kasture et al., pharmaceutical engineering , B.S.Shah prakashan, page no :79-
95.
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46. THANK YOU
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