Laboratory

1. ABSTRACT
This experiment to study the effects of temperature on saponification reaction of ethyl acetate
and sodium hydroxide in batch reactor. The batch reactor is the generic term for a type of vessel
widely used in the process industries. In the first experiment, the calibration curve for calibration
versus conductivity has been plotted by preparing 1 L of 0.1 M sodium hydroxide (NaOH)
solution and 1 L of 0.1 M sodium acetate (Na(Ac)) solution. From the curve, the conductivity
have been determined in 100 ml of deionised water for 0%, 25%, 50%, 75% and 100%
conversions. In the second experiment, 2 L of 0.1 M of acetyl acetate and 2 L of 0.1 M sodium
hydroxide was prepared. Then, the reactants were put into the jacketed reactor via the opening
that are located at the top of the reactor. For the first part, the temperature of the water was set at
30°C that will be the same as the reactor and reactant temperature. Then, the stirrer was switched
on. After that, the stirrer speed was set to the minimum speed. After 30 minutes later,
conductivity was observed. The reading was recorded and the steps were repeated for
temperature of 50°C after we collected the mixture in a beaker. Last but not least, after finishing
all the steps in the experiments, mixture inside the reactor was drained off and the reactor was
clean properly. All liquid waste (mixture) was dispose immediately after each experiment.
Lastly, 4 L of deionised water was filled into the tank for cooling process. From the data that
obtained by conducting this experiment, the temperature in term of conversion which was have
the lower conductivity will made the high conversion. For example, at temperature 40oc have
lower conversion and high conductivity which is 8.15 mS/cm. To increase the efficiency batch
reactor, there are some recommendation, firstly, oversize the reactor discharge pumps to drive
the external recirculation through a static mixer into the highly mixed zones. Secondly is a use a
jacketed pump for steam or hot oil ensures consistent temperature through the loop and a better
end product.
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2. INTRODUCTION
First of all, as concerned, the experiment was conducted to study the effect of
temperature on saponification reaction of ethyl acetate and sodium hydroxide in batch reactor. A
batch reactor was a reactor which characterized by its operation. This means the reactor reached
steady state was called batch reactor. The Batch reactor was a generic term for a type of vessel
widely used in the process industries. The vessels of this type were used for a variety of process
operations such as solids dissolution, product mixing, chemical reactions, batch distillation,
crystallisation, liquid or liquid extraction and polymerisation. In some cases, they were not
referred to as reactors but have a name which reflects the role they perform
There were many types of batch reactor such as FED batch rector, stirred batch reactor,
and semi batch reactor. Besides, the reactants and the catalyst in batch reactor were placed in the
reactor which was then closed to transport of matter. The reaction was allowed to proceed for a
given time where upon the mixture of unreacted material together with the product is withdrawn.
Besides that, provision for mixing may be required. Next, in batch reactor, all the reactants are
loaded at once, the concentration then varies with time, but at any one time it was uniform
throughout. Somehow, agitation served to mix separate feeds initially and to enhance heat
transfer. In addition, batch reactors were popular in practice because of their flexibility with
respect to reaction time and to the kinds and quantities of reactions that can be performed.
Batch reactor
2

3. The above picture was the example of image or sketched batch reactor vessels. The
characteristics of a batch reactor were that the total mass of each batch was fixed, each batch was
a closed system, and the reaction time for all elements of fluid was the same. Apart from that,
this reactor was less preferred because it involves high cost of operation and the product quality
more variable than with continuous operation. Hence, the high cost of operation was an example
of disadvantage of batch reactor.
For further information, a batch reactor was used in chemical processes for small scale
operation which were for testing new processes that have not been fully developed, for the
manufacture of expensive products, and for processes that are difficult to convert into continuous
operations. Other than that, the main advantage of a batch reactor was high conversion, which
can be obtained by leaving the reactant in the reactor for long periods of time, but it also has the
disadvantages of high labor costs per batch and the difficulty of large scale production. In a batch
reactor, all the reactants were loaded at once. The concentration then varies with time, but at any
one time it is uniform throughout. Agitation serves to mix separate feeds initially and to enhance
heat transfer. Besides, these reactors were popular in practice because of their flexibility with
respect to reaction time and to the kinds and quantities of reactions that can be performed.
As this experiment involved the saponification process, hence, the term saponification
will be defined. The term of saponification was the name given to the chemical reaction that
occurs when a vegetable oil or animal fat that was mixed with a strong alkali. The products of
the reaction are two which was soap and glycerin. Water was also present, but it does not enter
into the chemical reaction. The water was only a vehicle for the alkali, which was otherwise a
dry powder.
At last but not least, the oils used in modern handmade soap were carefully chosen by the
soap maker for the character they impart to the final soap. Coconut oil creates lots of glycerin,
makes big bubbly lather, and was very stable. Olive oil has natural antioxidants and its soap
makes a creamier lather. Tallow, or rendered beef fat, makes a white, stately bar that was firm
and created abundant lather. Many other oil can be used, each one for a specific reason. The
alkali used in modern soap was either potassium hydroxide that was used to make soap or liquid
soap because of its greater solubility, or sodium hydroxide that was used to make bar soap.
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4. LITERATURE REVIEW
The usual agitator arrangement is a centrally mounted shaft with an overhead drive unit.
Impeller blades are mounted on the shaft. A wide variety of blade designs are used and typically
the blades cover about two thirds of the diameter of the reactor. Where viscous products are
handled, anchor shaped paddles are often used which have a close clearance between the blade
and the vessel walls.(Christe John Geankoplis. Transport Process and Separation Process
Principle)
Most batch reactors also use baffles. These are stationary blades which break up flow
caused by the rotating agitator. These may be fixed to the vessel cover or mounted on the side
walls. Despite significant improvements in agitator blade and baffle design, mixing in large
batch reactors is ultimately constrained by the amount of energy that can be applied. On large
vessels, mixing energies of more than 5 Watts per litre can put an unacceptable burden on the
cooling system. High agitator loads can also create shaft stability problems. Where mixing is a
critical parameter, the batch reactor is not the ideal solution. Much higher mixing rates can be
achieved by using smaller flowing systems with high speed agitators, ultrasonic mixing or static
mixers. (H. Scott Fogler, Elements of Chemical Reaction Engineering)
A batch reactor is used for small-scale operation, for testing new processes that have not
been fully develop, for the manufacture of expensive products, and for processes that are difficult
to convert to CSTR. The reactor can be charged throught the holes at the top. A batch reactor has
neither inflow nor outflow of reactants or products while the reaction is being carried out: Fjo =
Fj = 0.
In – Out + Generation = Accumulation
V
FA 0
FA
rA dV
dN A
dt
V
dN A
dt
rA dV
4

5. (H. Scott Fogler, Elements of Chemical Reaction Engineering)
There are some advantage and disadvantage for using batch reactor. For advantages:
production of high cell densities due to extension of working time (particularly important
in the production of growth-associated products)
controlled conditions in the provision of substrates during the fermentation, particularly
regarding the concentration of specific substrates as for ex. the carbon source
control over the production of by-products or catabolite repression effects due to limited
provision of substrates solely required for product formation
the mode of operation can overcome and control deviations in the organism's growth
pattern1 as found in batch fermentation
allows the replacement of water loss by evaporation
alternative mode of operation for fermentations leading with toxic substrates (cells can
only metabolize a certain quantity at a time) or low solubility compounds
increase of antibiotic-marked plasmid stability by providing the correspondent antibiotic
during the time span of the fermentation
no additional special piece of equipment is required as compared with the batch
fermentation mode of operation
For Disadvantages:
It requires previous analysis of the microorganism, its requirements and the
understanding of its physiology with the productivity.
It requires a substantial amount of operator skill for the set-up, definition and
development of the process.
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6. In a cyclic fed-batch culture, care should be taken in the design of the process to ensure
that toxins do not accumulate to inhibitory levels and that nutrients other than those
incorporated into the feed medium become limiting, Also, if many cycles are run, the
accumulation of non-producing or low-producing variants may result.
The quantities of the components to control must be above the detection limits of the
available measuring equipment.
(H. Scott Fogler, Elements of Chemical Reaction Engineering)
OBJECTIVE
Firstly, the purpose of this experiment was to study the effects of temperature on
saponification reaction of ethyl acetate and sodium hydroxide in batch reactor. In this
experiment, two difference temperatures was used to measure the values of conductivity which is
directly proportional to the concentration of reactants inside the tanks. Hence, the time required
for completed reaction can be known when the values of conductivity become constant.
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7. METHODOLOGY
5.1 Materials/Apparatus
a) 2 L Fermenter
b) Dissolve oxygen probe
c) Ruler
d) Caliper
e) 2 L Distilled water
f) N2 and O2 supply
g) 2 g NaCl
h) 5 ml cooking oil (antifoam)
5.2 Geometric of Stirred Tank Bioreactor
Dimension of components
Liter/mm
Dimension of components
Liter/mm
Operating volume
2L
Ratio of P/D
0.38
Liquid height (L)
15.0cm
Ratio of B/D
0.07
Tank or vessel diameter (D)
21.0cm
Impeller height (I)
180mm
Ratio 0f L/D
57.74
Ratio of I/D
0.86
Impeller diameter (P)
80mm
Number of impeller
2
Baffle width (B)
15mm
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8. 5.3 Determination of KLa at different air flow rate
1. The agitation of bioreactor is set to 300 rpm.
2. Oxygen concentration of the solution is lowered by gassing the liquid out with N2 at 9
L/min until saturated and the flow is stopped.
3. O2 is supplied to the bioreactor at flow rate of 1.0 L/min until saturated, then the flow is
stopped.
4. CL value is obtained at constant time interval during aeration.
5. Steps 2-4 are repeated for different oxygen flow rate (1.5 and 2 L/min).
6. The KLa of stirred tank reactor is determined at different air flow rate.
5.4 Determination of KLa at different agitation speed
1. The agitation of bioreactor is set to 200 rpm.
2. Oxygen concentration of the solution is lowered by gassing the liquid out with N2 at 9
L/min until saturated and the flow is stopped.
3. O2is supplied to the bioreactor at flow rate of 1 L/min until saturated, and then the flow is
stopped.
4. CL value is obtained at constant time interval during aeration.
5. Steps 1-4 are repeated for different agitation speed (400 and 600 rpm).
6. The KLa of stirred tank reactor is determined at different agitation speed.
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9. RESULTS
Molar mass of ethyl-acetate = 88.11g/mol
Molar mass of sodium hydroxide = 40 g/mol
Density of ethyl-acetate =0.895 g/ml
At T = 400C
Time (min)
Conductivity
5
9.92
10
8.90
15
8.50
20
8.42
25
8.20
30
8.15
At T = 600C
Time (min)
Conductivity
5
8.0
10
7.9
15
7.7
20
6.2
25
5.9
30
5.2
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10. Calculation
For NaOH,
NaOH = 9 mL
120 mL NaOH = 20 L
1.5 L NaOH = ?
1.5 x 6 = 9 mL
For EtAC,
= 10.17
M1V1 = M2V2
(10.17)V1 = (0.1)(1.5)
V1 = 15 mL
Conversion + 100 ml DI water
Conductivity,(mS/cm)
100 ml NaOH
for 0% conversion
35.8
75 ml NaOH + 25 ml Na(Ac) for
25% conversion
30.3
50 ml NaOH + 50 ml Na(Ac)
for 50% conversion
24.9
25 ml NaOH + 75ml Na(Ac)
for 75% conversion
19.5
100 ml Na(Ac)
for 100 % conversion
14.55
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11. DISCUSSIONS
Plot the calibration curve of conversion vs. conductivity and discuss relationship between these
parameters.
Graph calibration curve of conversion,X versus
conductivity,mS/cm
120
Conversion,x(%)
100
80
60
40
y = -4.688x + 167.2
R² = 0.999
20
0
0
-20
5
10
15
20
25
30
35
Conductivity, (mS/cm)
From the graph, the conversion is increase when the conductivity is decrease.
Slope=m
y=-4.6887x + 167.27
m=-4.6887
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40

12. Plot a graph of conductivity / conversion vs. temperature. Compare the result for each
temperature in term of conversion etc.
9
8
Conductivity,ms/cm
7
6
5
4
3
2
1
0
0
10
20
30
40
50
60
70
Temperature,(o C)
1) Temperature (40 oc)
Conductivity-8.15 mS/cm
2) Temperature(60 oc)
Conductivity-5.2 mS/cm
From the graph, we can compare the result for temperature in term of conversion which the
lower the conductivity, the higher the conversion. For example, at temperature 40oc have lower
conversion and high conductivity which is 8.15 mS/cm.
1. Give 3 examples on the application of batch reactor in chemical process industries.
i.
Fermentation
ii.
Intermediate or one shot production
iii.
Pharmaceutical
12

13. iv.
Small scale production
2. Suggest a method or way to improve the efficiencies of batch reactor.
Oversize the reactor discharge pumps to drive the external recirculation through a
static mixer into the highly mixed zones.
A jacketed pump for steam or hot oil ensures consistent temperature through the
loop and a better end product.
Using multiple injection points with nozzles at the tank entrances will increase
velocity for better mixing. However, these flow restrictions will increase
horsepower requirements compared to simple recirculation.
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14. CONCLUSION AND RECOMMENDATION
CONCLUSION
From this experiment, we can conclude that the conductivity is inversely
proportional to temperature. Based on the result, for temperature in term of conversion which
the lower the conductivity, the higher the conversion as for example, at temperature 40oc that has
lower conversion will have high conductivity which is 8.15 mS/cm. Particles can only react
when they collide. If a substance heat up, the particles move faster and so collide more
frequently. Apart from that, it is obviously that from the result we obtained, the objective of this
experiment successfully achieved.
RECOMMENDATION
1.
Oversize the reactor discharge pumps to drive the external recirculation through a
static mixer into the highly mixed zones.
2.
Used a jacketed pump for steam or hot oil ensures consistent temperature through
the loop and a better end product.
3.
Using multiple injection points with nozzles at the tank entrances will increase
velocity for better mixing. However, these flow restrictions will increase horsepower
requirements compared to simple recirculation.
4.
Before start the experiment all the apparatus must be clean up and dry before pour
any chemical solution..
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15. REFERENCES
H. Scott Fogler, Elements of Chemical Reaction Engineering (Third Edition), Prentice
Hall, International Series.
Transport Process and Separation Process Principle (Include Unit Operations),
4th
edition, Christe John Geankoplis.
Optimisation of Batch Reactor Operation. Retrieved on 22 February 2011 from
http://www.strath.ac.uk/Other/cpact/Project5/project5sum.htm.
Batch
Reactor.
Retrieved
on
22
February
2011
from
http://www.scribd.com/doc/22995623/Batch-Reactors.
Fed-Batch
Fermentations.
Retrieved
on
22
February
2011
from
http://userpages.umbc.edu/~gferre1/fedbatch.html#Some%20examples%20of%20fedbatch%20use%20in%20industry.
Improve Batch Reactor Temperature Control. Retrieved on 22 February 2011 from
http://www.chemicalprocessing.com/articles/2008/088.html.
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