UNIT OPERATIONS (unit 2) process chemistry

UNIT OPERATIONS
SUBMITTED TO : MR. ARUN KUMAR SUBMITTED BY : SAKET
M. PHARMACY
PHARMACEUTICAL CHEMISTRY
DEPARTMENT OF PHARMACEUTICAL SCIENCE
GURUGRAM UNIVERSITY, GURUGRAM

“
 Unit Operations gives idea about:
• specific physical operation;
• different equipment - its design,
• material of construction and operation;
• calculation of various physical parameters (mass flow, heat
flow, mass balance, power and force etc.).
Unit operations involve a physical change or chemical
transformation such as separation, crystallization, evaporation,
filtration, polymerization, isomerization, and other reactions
INTRODUCTION

EXTRACTION
 Extraction defined as the treatment of the plant or animal tissues with solvent, whereby the
medicinally active constituents or API are dissolved & most of the inert matter
remain undissolved.
 Menstruum: solvent used for extraction.
 Marc: the insoluble material that remains extraction.

“
 Methods of Extraction
1.Maceration
2.Percolation
3.Decoction
4.Digestion
5.Infusion
4
Continued….

Extraction with reflux
• A mixture of reactants and solvent is placed in a
suitable vessel, such as a round bottom flask. This
vessel is connected to a water-cooled Liebig or Vigreux
condenser, which is typically open to the atmosphere at
the top.
• The reaction vessel is heated in order to boil the
reaction mixture; vapours produced from the mixture are
condensed by the condenser, and return to the vessel
through gravity.
• The purpose is to thermally accelerate the reaction by
conducting it at an elevated, controlled temperature (i.e.
the solvent's boiling point) and ambient pressure.
5

Extraction with
agitation
 Agitation is the movement of one or more
components of a mixture to improve contact.
 Putting into motion by shaking or stirring, often
to achieve mixing.
6

Counter current
extraction
 A method of multiple liquid-liquid extractions is countercurrent extraction.
 It permits the separation of substances with different distribution coefficients
(ratios).
 A clever design known as Craig apparatus is used for this purpose (Lyman
C. Craig, 1943).
June 9, 2023
Annual Review
7

Criag apparatus
 Craig apparatus consists of a series of glass tubes (r: 0, 1, 2..) that are designed and arranged such that the
lighter liquid phase is transferred from one tube to the next.
 The liquid-liquid extractions are taking place simultaneously in all tubes of the apparatus which is usually driven
electromechanically.
 The lower (heavier) phase of the two-phase solvent system (e.g. water, blue layer in the picture) is the "stationary
phase" red laver in the picture) is the "mobile phase", whereas the upper (lighter) phase (e.g. hexane , red layer in
picture)
 Here, wet raw material is pulverized using toothed disc disintegrators to produce fine slurry.
 The material to be extracted is moved in one direction (generally in the form of fine slurry) within a cylindrical
extractor where it comes in contact with extraction solvent.
 Finally, sufficiently concentrated extract comes out at one end of the extractor while the marc falls out
from the other end.
8

FILTRATION
Filtration is a process of separation of solids from a fluid by passing the same through a porous medium that
retains the solids but allows the fluid to pass through.
THEORY:
 The mathematical models for flow through a porous medium, cake filtration, and granular bed filtration
may differ, but all follow this basic rule. The energy lost in filtration is proportional to the rate of tow per unit
area.
 The flow of liquid through a filter follows the basic rules that govern flow of any liquid through a medium
offering resistance.
 The rate of flow may be expressed as:
Rate: Driving force/ Resistance
June 9, 2023
Annual Review
10

Pressure
filtration
 This process is owing to the difficulty in removing the cake they are mechanically
complex and expensive.
 The filtration rate is influenced by properties of the slury.
 The rate goes up with increased pressure.
June 9, 2023
Annual Review
11

Plate and Frame
Press
 Simplest of all pressure filters.
 Most widely used press.
 Used for a high degree of clarification of the
fluid.
 When clarity is the main objective, a "batch"
mode of operation is applied.
 As the name implies, the plate and frame filter
press is an assembly of hollow frames and
solid plates that support filter media.
June 9, 2023
Annual Review
12

Advantages Disadvantages
 High solids content cake.
 Can dewater hard-to-dewater sludges.
 Very high solids capture.
 Only mechanical device capable of producing a
cake dry enough to meet landfill requirements in
some locations..
 Large quantities of inorganic conditioning
chemicals are commonly used.
 High capital cost, especially for variable-volume
filter presses.
 Replacement of the media is time consuming.
13

Vacuum Filtration
 Employed on a large scale.
 Rarely used for the collection of crystalline precipitates or sterile
filtration.
 Simple and reliable machines, and therefore have gained wide
acceptance in the chemical, food and pharmaceutical industries.
14

Rotary Drum
Filter
 This is divided into sections, each connected to
a discharge head..
 Each filter unit is rectangular in shape.
 Each unit has a perforated metal surface and is
covered with filter cloth.
15

 Developed to overcome large problem of filter
press and leaf filter. It is very versatile filter.
 It is used generally for those operation in which
the volume is very large.
 It is used where colloidal particles.
 It is used for production of wallboard from
gypsum.
 It can not be used for mixture of colloidal and
course particles.
 It must be used continuously.
16

Centrifugal Filtration
 General class of solids recovery devices.
 Centrifugal force is used to affect the passage of the
liquid through the filter medium.
 This type of filtration is particularly advantageous
when very fine particles are involved.
17

Perforated
Basket
 The device consists of a perforated
metal basket mounted on a vertical
axis.
 Rotation speed 20 to 25
revolutions per second.
18

 Centrifuges have a clean appearance and have
little to no odor problems.
 Not only is the device easy to install and fast at
starting up and shutting down, but also only
requires a small area for operation.
 They can be selected for different applications.
 The device is simple to operate.
 Centrifuge has more process flexibility and higher
levels of performance.
 The machine can be very noisy and can cause
vibration.
 The device has a high-energy consumption due
to highG-forces.
 High initial capital costs.
19

Azeotropic
Distillation
 The technique of addition of another component to form a new low boiling point azeotropic
solution such as benzene can be added to the solution of ethanol and water in
azeotropic distillation.
 The azeotropic distillation unit consists of a container to feed the azeotrope, decanter and
steamer.
 For example; the mixture of acetic acid and water can be separate out with the addition of
an ester like n-butyl acetate.
 Remember the boiling point of acetic acid is 118.1°C and water is100°C.
 Addition of ester whose boiling point is 125°C forms a minimum-boiling azeotrope with water
with boiling point 90.2°C.
20

Continued…..
 Hence azeotropic mixture will be distilled over
as vapor and leave acetic acid at bottoms. The
overhead vapor is condensed and collected in
a decanter.
 Here it forms two insoluble layers in which the
top laver contains pure butyl acetate with water,
and a bottom layer contains pure water
saturated with butyl acetate.
 The top layer is returned to the distillation
column and bottom layer is sent to another
column for the recovery of the ester by
steam stripping.
21

How it works.
 The entrainer decreases the boiling point of azeotropic solution and separates the components of
mixture at different boiling points.
 When azeotropic mixture is heated with entrainer, the condensed over head vapor forms two liquid
phases and collects in the decanter.
 In decanter, the top layer contains benzene whereas bottom layer contains water.
 The top layer of benzene again back to first column as reflux and source of entrainer whereas
bottom layer of water back to 2nd column.
 The bottom of 2nd column contains mixture of ethanol and water which transfers to 3rd column for
distillation.
 Third column contains pure water at bottom and distillate is returned to the1st
column for recycling.
22

Azeotropic distillation of ethanol
 Another example of azeotropic distillation is separation of ethanol with water from its aqueous
solution.
 The boiling point of water is 100 °C and boiling point of ethanol is 78.3°C.
 By addition of benzene to the azeotropic mixture as entrainer, ethanol can be separated out from the
solution.
 Presence of benzene forms a new solution of minimum boiling point with 22.8 mole% ethanol, 23.3
mole% water and 53.9 mole% benzene which boils at 64.86 °C.
 Pure water leaves as the overhead product and pure ethanol leaves the column as bottoms product.
23

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 obsolete by vacuum
distillation.
 Steam distillation remains important in certain
industrial sectors.
June 9, 2023
Annual Review
24

Continuied…
 Many organic compounds tend to decompose at high sustained temperatures.
 Separation by distillation at the normal (1 atmosphere boiling points is not an option, so water or steam is
introduced into the distillation apparatus.
 The water vapor carries small amounts of the vaporized compounds to the condensation flask, where the
condensed liquid phase separates, allowing for easy collection.
 This process effectively allows for distillation at lower temperatures, reducingthe deterioration of the desired
products.
 If the substances to be distilled are very sensitive to heat, steam distillation may be applied under reduced
pressure, thereby reducing the operating temperature further.
 After distillation the vapors are condensed.
 Usually the immediate product is a two-phase system of water and the organic distillate, allowing for
separation of the components by decantation, partitioning or other suitable method.
June 9, 2023
Annual Review
26

Principle
 When a mixture of two practically immiscible liquids is heated while being agitated to expose the surface of
each liquid to the vapor phase, each constituent independently exerts its own vapor 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.
 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.
June 9, 2023
Annual Review
27

UNIT OPERATIONS (unit 2) process chemistry

UNIT OPERATIONS (unit 2) process chemistry

More Related Content

What's hot (20)

Similar to UNIT OPERATIONS (unit 2) process chemistry (20)

Recently uploaded (20)

UNIT OPERATIONS (unit 2) process chemistry