Experiment _ 1,2,3,4
description
Transcript of Experiment _ 1,2,3,4
Experiment # 1
CONTINUOUS STIRRED TANK REACTOR
Objective:
To find the reaction rate constant in a continuous stirred tank reactor.
Thoery:
Ideal steady-state flow reactor is called the mixed reactor, the backmix reactor, the ideal stirred
tank reactor, the C* (meaning C-star), CSTR, or the CFSTR (constant flow stirred tank reactor),
and, as its names suggest, it is a reactor in which the contents are well stirred and uniform
throughout. Thus,the exit stream from this reactor has the same composition as the fluid within
the reactor. We refer to this type of flow as mixed pow, and the corresponding reactor the mixed
pow reactor, or MFR.
Steady-State Mixed Flow Reactor:
The performance equation for the mixed flow reactor makes an
accounting of a given component within an element of volume of
the system. But since the composition is uniform throughout, the
accounting may be made about the reactor as a whole. By
selecting reactant A for consideration,
input = output + disappearance by reaction + accumulation
FAo = voCAo is the molar feed rate of component A to the reactor,
then considering the reactor as a whole we have
input of A, moles/time = FAo(l - XAo) = FAo
output of A, moles/time = FA = FAo(l - XA)
disappearance of A by reaction = (-rA)V = moles of A reacting/[(time)(volume of fluid)] (Vr)
FAo XA=(-rA)V
which on arrangement becomes
Description:
The continuous stirred tank reactor in the form of either a single tank or more often tank in series
is used widely and in particularly suitable for liquids phase reaction. It is particularly used in the
organic chemicals industry. Advantages include consistent product quality, straightforward
automatic control and low manpower requirements.
Reaction is monitored by conductivity probe as the conductivity probe of solution changes with
conversion of the reactants to product. This means that the inaccurate and inconvenient process
of titration, which was formally used to monitor the reaction process, is no longer necessary.
The Reactor Vessel:
The reactor vessel is set on a base plate which is designed to be located on
the four studs of the CEX service unit and then secured by thumbnuts. The reactor is supported
by three pillars; position the reactor on the CEX service unit such that a single pillar is to the
front.
A stainless steel coil inside the reactor provides the heat transfer surface for either heating or
cooling the chemical reactants. The coil is connected either to be hot water circulator or the CW-
16 chiller. The coil inlet is at the front of the reactor and the coil return is at the rear of the
reactor.
A turbine agitator works in conjunction with a baffle arrangement to provide efficient mixing and
heat transfer. The agitator is driven by an electric motor mounted on the lid of the reactor. The
motor is driven by a variable speed unit mounted in the front of the service unit. The socket for
the motor electrical plug is sited at the rear of the service unit.
Glands in the reactor lid house the conductivity and temperature sensors provided with the
service unit. The larger of the two glands is for the conductivity probe. The glands are unscrewed
by hand, the probes inside completely into the reactor until the rest on the reactor base and then
the glands re-tightened by hand. Sockets in the side of the console on the service unit are
provided to connect each other. There are different sizes so that the probe cannot be connected
wrongly.
Chemical reagents are pumped from the two feed tanks into the reactor separately through
connectors on the base of the reactor. The two feed pumps of the service unit are connected to
these. As reagents are pumped into the reactor, the level increases until it finally over flows the
stand pipe and flows to the drain. The stand pipe may be adjusted in high by loosening the
hexagonal baking nut. A mark is etched onto the stand pipe. For maximum operating volume of
reactor, this mark should be aligned with the baking nut. A stop prevents the stand pipe from
being completely removed, and this also defined the minimum working of volume which is the
half of the maximum volume.
Chemical Reaction:
NaOH + CH3COOC2H5 CH3COONa + CH3CH2OH
Procedure:
Make up to 3liter batches of 0.06M sodium hydroxide.
Make up to 3 liter batches of 0.04M ethyl acetate.
Remove the lid of the reagent vessels and carefully fill with the reagents.
Adjust the set point of temperature controller to 30°C.
Collect conductivity data until a steady state condition is reached in the reactor and this
takes approximately 30 to 45 minutes.
Using the calibration graph for each of the feed pump, set the pump speed control at
specified flow rate.
Set the agitator speed controller to 7.
Switch on both feed pumps and the agitator motor.
After a few minutes the temperature sensor tip will be covered (about 25mm of liquid in
the reactor).
Switch on the hot water circulator.
Calibration of Pump 1:
Potentimetric readings Flow rate(ml/s)
2 0.308
4 0.512
6 0.772
8 1.262
10 1.438
Graph of pump 1:
1 2 3 4 5 6 7 8 9 10 110
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Series2
Rev
Flow
rate
Calibration of Pump 2:
Potentimetric readings Flow rate(ml/s)
3 0.317
5 0.678
7 0.896
8 1.121
9 1.223
Graph of pump 2:
2 3 4 5 6 7 8 9 100
0.2
0.4
0.6
0.8
1
1.2
1.4
Series2
Rev
Flow
rate
Time vs Conductivity data:
Given Data:
Molarity of NaOH = 0.06M
Molarity of CH3COOC2H5 = 0.06M
Volume of the solutions =3.0 dm3
Calculations:
For NaOH
Molarity = no. of moles of solute / dm3 of solution
0.06 = no. of moles / 3
Moles = 0.18
Molar mass = 40g
Time Conductivity
(sec) (mS)
0 0.03
120 1.90
240 2.10
360 2.89
480 3.22
600 3.67
720 4.55
840 5.90
960 5.86
1080 5.84
1200 5.82
Mass of NaOH= 40×0.18 = 7.2g
For CH3COOC2H5
Molarity = no. of moles of solute / dm3 of solution
0.04 = no. of moles / 3
moles = 0.12
Molar mass = 98g
Mass of CH3COOC2H5 = 98×0.12 = 10.56g
Density of CH3COOC2H5 = 0.897 g / ml
Volume of CH3COOC2H5 = Mass / Density
= 10.56 / 0.897
Volume of CH3COOC2H5 = 11.773 ml
Nomenclature:
aµ = NaOH conc. in feed vessel
aᴏ = NaOH conc. in mixed feeds
a1 = NaOH conc. in reactor at time t
a∞ = NaOH conc. in reactor at ∞ time
bµ = CH3COOC2H5 conc. in feed vessel
bᴏ = CH3COOC2H5 conc. in mixed feeds
b1 = CH3COOC2H5 conc. in reactor at time t
b∞ = CH3COOC2H5 conc. in reactor at ∞ time
cµ = CH3COONa conc. in feed vessel
cᴏ = CH3COONa conc. in mixed feeds
c1 = CH3COONa conc. in reactor at time t
c∞ = CH3COONa conc. in reactor at ∞ time
F = Total volume feed rate
Fa = Volume feed rate of NaOH
Fb = Volume feed rate of CH3COOC2H5
k = Specific Rate constant
Xa= Conversion of NaOH
Xc= Conversion of CH3COONa
Λ= Conductivity
Λᴏ= Initial Conductivity
Λ1 = Conductivity at time t
Λ ∞ = Conductivity at ∞ time
Given:
Fa = 86.28ml / min
Fb = 85.68ml / min
aµ = 0.06 mol / dm3
bµ = 0.04 mol / dm3
T = 306 K
Vr = 2 litre
aᴏ= (Fa/ Fa+ Fb) × aµ
= (86.28 / 85.68 +86.28 ) × 0.06
aᴏ = 0.0301 moles / dm3
bᴏ= (Fb/ Fa+ Fb) × bµ
= ( 85 .68/85.68 +86.28 ) × 0.04
bᴏ = 0.01993 moles / dm3
c∞ = aᴏ
Λc∞ = 0.070 [ 1 + 0.0284 (T – 294) ] ×c∞
= 0.070 [ 1 + 0.0284 (306 – 294) ] × 0.0301
Λc∞ = 2.825 × 10-3
Λao = 0.195 [ 1 + 0.0184 (T – 294) ] × aᴏ
= 0.195 [ 1 + 0.0184 (306 – 294) ] × 0.0301
Λao = 7.165 × 10-3
Assume cᴏ = 0
Λᴏ= Λao
Λᴏ = 7.165 × 10-3
a∞ = aᴏ - bᴏ for aᴏ ≥ bᴏ
a∞ = 0 for aᴏ<bᴏ
a∞ = 0.0301-0.01993=0.01017
Λao= 0.195 [ 1 + 0.0184 (T – 294) ] × a∞
= 0.195 [ 1 + 0.0184 (306 – 294) ] × 0.01017
Λao = 2.4210× 10-3
Λ∞ = Λc∞ +Λa∞
Λ∞ = 2.825 × 10-3 + 2.4210× 10-3
Λ∞ = 5.2460× 10-3
a1 = ( a∞ - aᴏ )[ Λᴏ - Λt / Λᴏ - Λ∞ ] + aᴏ
a1 = (0.01017 – 0.0301)[ 7.165 × 10-3 – 5.82 × 10-3/7.165 × 10-3 –
5.2460× 10-3] + 0.0301
a1 = 0.01613mol / dm3
c1 = c∞[Λᴏ - Λ1 / Λᴏ - Λ∞ ] (for cᴏ = 0)
c1 = 0.03 [ 7.165 × 10-3 – 5.82 × 10-3/7.165 × 10-3 – 5.2460× 10-3]
c1 = 0.0mol / dm3
Xa= aᴏ- a1/ aᴏ
= 0.0301- 0.01613 / 0.0301
Xa= 0.4641
Xc= c1/ c∞
= 0.01116 / 0.01993
Xc= 0.56
k = ( Fa+ Fb / V ) × (aᴏ - a1 / a12 ) ×1/ 1000 × 60
= ( 86.28+85.68 / 2) × (0.0301 – 0.01613/ 0.016132 ) ×1/ 1000 × 60
k = 0.079 mol / dm3 s
Results:
k = 0.079 mol / dm3 s (reaction rate constant)
k= 0.111 mol/ dm3 s(from literature)
Experiment # 2
LIQUID PHASE BATCH REACTER
Objective:
To determine the order and value of the rate constant for the homogeneous liquid
Phase reaction of caustic soda with ethyl acetate in a batch reactor:
NaOH + CH3COOC2H5 C2H5OH + CH3COONa
Introduction:
A batch reactor may be described as a vessel in which chemicals are placed to react.
Batch reactors are normally used in small-scale laboratory set-ups to study the kinetics of
chemical reactions. To determine the order and rate constant of a chemical reaction, the variation
of a property of the reaction mixture is observed as the reaction progresses. Data collected
usually consist of changes in variables such as concentration of a component, total volume of the
system or a physical property like electrical conductivity. The data are then analyzed using
pertinent equations to find desired kinetic parameters.It is mostly used in food industries.
Construction:
A typical batch reactor consists of a tank with an agitator and integral heating/cooling system.
These vessels may vary in size from less than 1 litre to more than 15,000 litres. They are usually
fabricated in steel, stainless steel, glass lined steel, glass or exotic alloy. Liquids and solids are
usually charged via connections in the top cover of the reactor. Vapors and gases also discharge
through connections in the top. Liquids are usually discharged out of the bottom.
Advantages of Batch Reactor:
The advantages of the batch reactor lie with its versatility. A single vessel can carry out a
sequence of different operations without the need to break containment. This is particularly
useful when processing toxic or highly potent compounds.
Material balance :
rate of input - rate of output- rate of disappearance = rate of accumulation
Fj0 – Fj +∫o
v
rj dV = dNjdt
A batch reactor has neither inflow nor outflow of reactants or products while the reaction is being
carried out. Fj0 = Fj =0 .The resulting general mole balance on species j is
∫o
v
rj dV = dNjdt
If the reaction mixture is perfectly mixed so that there is no variation in the rate of
reaction throughout the reactor volume, rj can be taken out of the integral and the
mole balance can be written as
dNjdt
= rj v
Consider an elementary reaction …
aA + bB =cC + dD
Rate of disappearance of A =-rA =dNA
dt
Where NA is the number of moles in the reactor at any time Consatnt volume conditions can be
assumed for most of the liquid phase reactions or for gas phase reactions with no change in
number of moles
Then NA = V * CA where CA is the concentration of A in the reactor.
-rA =dCadt
Then for the reaction given above
-rA= kCaACbB
Where …. k= rate constant
a is the order of reaction w.r.t A and b is the order w.r.t B. If the order of the reaction w.r.t each
reactant are equal to the stoichiometric coefficients of these reactants, then the reaction is
elementary. Else it is nonelementary. Order and the rate constants of the reaction can be obtained
by experiments.
Mainly two types of analysis may be used for rate law determination.
(a) Integral method of analysis
(b) Differential method of analysis.
Procedure:
In the reactor shown in fig., mix 1.0 liter of the 0.1M caustic soda solution with 1.0 liter
of the 0.1M ethyl acetate solution at an arbitrary time (t = 0) at room temperature. Switch
on the stirrer immediately and set it to an intermediate speed to avoid splashing.
Start the timer as soon as you start mixing the reactants.
After a certain time interval, use a pipette to withdraw 25ml sample from the reactor, and
immediately quench it with 25ml of excess 0.05M hydrochloric acid.[You should have
the quenching acid sample ready before taking the sample from the reactor.]
Add 2 - 3 drops of phenolphthalein to the quenched sample and back titrate with 0.05M
NaOH solution until the end point is detected (in this case a stable pink color) .
Record the amount of NaOH used in the titration.
Repeat steps (3) - (5) every 3 minutes for the first five samples and thereafter every 5
minutes. Take a total of 14 samples making sure that you record the time for each new
sample.
Given Data:
Molarity of NaOH = 0.02M
Molarity of CH3COOC2H5 = 0.02M
Volume of the solutions = 28 liter
Calculations:
For NaOH
Molarity = no. of moles of solute / dm3 of solution
0.02 = no. of moles / 28
Moles = 0.56
Molar mass = 40g
Mass of NaOH= 40×0.56 = 22.4g
For CH3COOC2H5
Molarity = no. of moles of solute / dm3 of solution
0.02 = no. of moles / 28
moles = 0.56
Molar mass = 98g
Mass of CH3COOC2H5 = 98×0.56 = 54.88g
Density of CH3COOC2H5 = 0.897 g / ml
Volume of CH3COOC2H5 = Mass / Density
= 54.88 / 0.897
Volume of CH3COOC2H5 = 61.18 ml
Time (T) Conductivity (mS)
0 1.97
3 1.92
6 1.89
9 1.84
12 1.80
15 1.73
18 1.70
21 1.67
24 1.65
27 1.65
30 1.65
Nomenclature:
aµ = NaOH conc. in feed vessel
aᴏ = NaOH conc. in mixed feeds
a1 = NaOH conc. in reactor at time t
a∞ = NaOH conc. in reactor at ∞ time
bµ = CH3COOC2H5 conc. in feed vessel
bᴏ = CH3COOC2H5 conc. in mixed feeds
b1 = CH3COOC2H5 conc. in reactor at time t
b∞ = CH3COOC2H5 conc. in reactor at ∞ time
cµ = CH3COONa conc. in feed vessel
cᴏ = CH3COONa conc. in mixed feeds
c1 = CH3COONa conc. in reactor at time t
c∞ = CH3COONa conc. in reactor at ∞ time
F = Total volume feed rate
Fa = Volume feed rate of NaOH
Fb = Volume feed rate of CH3COOC2H5
k = Specific Rate constant
Xa= Conversion of NaOH
Xc= Conversion of CH3COONa
Λ= Conductivity
Λᴏ= Initial Conductivity
Λ1 = Conductivity at time t
Λ ∞ = Conductivity at ∞ time
Given:
Fa = 50ml / min
Fb = 50ml / min
aµ = 0.02 mol / dm3
bµ = 0.02 mol / dm3
T = 306 K
Vr = 56 litre
aᴏ= (Fa/ Fa+ Fb) × aµ
= (50/50+50 ) × 0.02
aᴏ = 0.01 moles / dm3
bᴏ= (Fb/ Fa+ Fb) × bµ
= (50/50+50 ) × 0.02
bᴏ = 0.01 moles / dm3
c∞ = aᴏ
Λc∞ = 0.070 [ 1 + 0.0284 (T – 294) ] ×c∞
= 0.070 [ 1 + 0.0284 (306 – 294) ] × 0.01
Λc∞ = 9.3 × 10-4
Λao = 0.195 [ 1 + 0.0184 (T – 294) ] × aᴏ
= 0.195 [ 1 + 0.0184 (306 – 294) ] × 0.01
Λao = 2.38 × 10-3
Assume cᴏ = 0
Λᴏ= Λao
Λᴏ = = 2.38 × 10-3
a∞ = aᴏ - bᴏ for aᴏ ≥ bᴏ
a∞ = 0 for aᴏ<bᴏ
a∞ = 0.01-0.01=0.0
Λao= 0.0
Λ∞ = Λc∞ +Λa∞
Λ∞ = 9.3 × 10-4 + 0.0
a1 = ( a∞ - aᴏ )[ Λᴏ - Λt / Λᴏ - Λ∞ ] + aᴏ
a1 = (0.0 – 0.01)[ 2.38 × 10-3 – 9.3 × 10-3 /2.38 × 10-3 –
9.3× 10-4] + 0.01
a1 = 0.007mol / dm3
c1 = c∞[Λᴏ - Λ1 / Λᴏ - Λ∞ ] (for cᴏ = 0)
c1 = 0.01 [2.38× 10-3 – 9.3 × 10-3/2.38× 10-3 – 9.3× 10-3]
c1 = 0.01mol / dm3
Xa= aᴏ- a1/ aᴏ
= 0.01- 0.007/ 0.01
Xa= 30
Xc= c1/ c∞
= 0.01 / 0.019
Xc= 0.5263
k = ( Fa+ Fb / V ) × (aᴏ - a1 / a12 ) ×1/ 1000 × 60
= ( 50+50 / 56) × (0.01 – 0.007/ 0.0072 ) ×1/ 1000 × 60
k = 0.065 mol / dm3 s
Results:
k = 0.065 mol / dm3 s (reaction rate constant)
k= 0.111 mol/ dm3 s(from literature)
References:
Levenspiel, O., "Chemical Reaction Engineering", 2nd ed., Wiley and Sons,
N.Y., p. 41 (1977).
Smith, J.M., "Chemical Engineering Kinetics", 3rd ed., McGraw-Hill Book
Comp., N.Y., p. 37 (1981).
Holland, C. D "An Introduction to Chemical Engineering Kinetics & Reactor
Design." Chp. 8, John Wiley Inc., N.Y., (1977).
Experiment # 3
TUBULAR FLOW REACTOR
Objective:
To measure heat generation and heat removal characteristics of methanol oxidation reaction.
Theory:
The methanol oxidation system developed corresponds in many respects to CSTR
system. Except for end effects the wire temperature is essentially uniform. Reaction occurs at a
single temperature and the system need not be considered a distributed-parameter system.
A plot of the rate of heat generation by reaction against wire temperature has a sigmoid shape. At
lower temperature, the reaction is rate controlled while at higher temperatures the reaction is
diffusion transport-controlled.
Depletion of reactants in the chamber is believed to be negligible under the conditions to be used.
The process of transport of reactants and products is a combination of molecular diffusion with
thermal and forced convection.
A plot of the heat removal rate against wire temperature will show the expected increase with
difference between wire temperature and chamber temperature. The heat removal corresponds to
that in a CSTR with a heat transfer surface. Heat removal from the wire occurs by radiation in
addition to convection and conduction.
Description:
A schematic diagram of the system is shown in the figure. The helium-oxygen mixture
is supplied from a cylinder, passed through a rotameter and fed to a sparger immersed in
methanol at 0oC. The saturated (or partially saturated) gas passes through a coil to the air-
jacketed reaction chamber which contains the platinum wire. A by-pass of the sparger is
provided. Reactor exit gases are vented within a fume hood. Hot air for the chamber jacket is
supplied by a hair-dryer type gun. The current control circuit is shown in figure.
The 90% helium & 10% oxygen mixture is premixed in a conventional cylinder. The gases
passes through a pressure regulator, shut-off valve, rubber tubing, control valve and rotameter to
the carburetor. High-pressure tubing (1/4-inch I.D) is used downstream of the rotameter. The
carburetor is a 2 1/2 -inch I.D, 8-inch long glass cylinder containing methanol in which a fritted
glass sparger is placed. The carburetor is immersed in ice water contained in a 4 ½-inch I.D.
wide-mouth vacuum flask. The carburetor gas passes to the reactor. A carburetor by-pass tube is
provided with a pinch clamp.
The reactor chamber is a 7/8-inch I.D. glass tube, 6 inches long, contained at the top of a second
glass tube (2-inch I.D., 18 inches long) through which hot air from a heat gun is blown.
The reactor feed gas passes through a tubing coil within the jacket for preheating prior to entering
the reactor. The platinum wire is suspended in a horizontal loop at the center of the reactor.
Exhaust gases from the reactor and the jacket are vented at the top of the reactor assembly. The
heat capacity of the system is kept deliberately low so that rapid temperature equilibrium can be
obtained. Resistance of the wire is measured with the commercial Kelvin double bridge circuit.
Electrical current for resistance measurements and for heating the wire is supplied by an
automobile storage battery and a solid-state control circuit.
The platinum wire (0.003 to 0.005 inch diameter, about 1.5 inches long) is spot welded to two
copper rods (3/32-inch diameter, tinned) and held by Teflon plug inserted (loose fit) in the top of
the reaction chamber. Hose in the plug allow gas exit and insertion of a thermometer.
Since wires are melted by overheating, spare assembly are kept on hand.
For reasons of safety, the reactor assembly and the carburetor are located behind Plexiglas shield
located within and exhaust hood. Provided the methanol concentration in the helium-oxygen
mixtures does not exceed that corresponding to saturation at 0oC, the carbureted gas is not
flammable at temperature below 200oC. With higher methanol concentration or at higher
temperatures, the mixtures may be flammable and/or explosive. To minimize the severity of a
possible explosion, the volumes of carbureted gas contained in the reactor and in the carburetor
are minimized.
Steady-State Plug Flow Reactor:
In a plug flow reactor the composition of the fluid varies from point to point along a flow
path; consequently, the material balance for a reaction component must be made for a differential
element of volume dV.
input = output + disappearance by reaction + accumulation
see for volume dV that
input of A, moles/time = FA
output of A, moles/time = FA + dFA
disappearance of A by reaction,( moles/time) = (-rA)dV.
= (moles A reacting)/ (time)(volume of fluid)
FA = FA + dFA + (-rA)dV
d FA = d[FAº (1-XA)]
FAº * d XA = (-rA)dV
Procedure:
The storage battery is charged and the methanol flash is cooled to 0oC.
Initial observations of spontaneous ignition and extinction are made in order to check the
activity of the wire.
Set a gas flow rate for which these phenomena are observable with chamber temperature
in the range of 25o-200oC. Usually flow rates in the range of 10-20% of full scale on the
rotameter are suitable, with a fix flow rate and reaction chamber temperature.
The resistance of the wire is measured for a range of wire currents.
Measurements without methanol in the feed give the heat removal-wire temperature curve since
the heat removal is equal to the electrical heat input.
If it is assumed that the heat removal for a given wire temperature is unaffected by the presence of
the methanol, then the heat of reaction can be taken as a difference in electrical heat inputs with
and without methanol present.
Experiment # 4
BATCH ENZYME REACTOR
Objective:
To determine Michaelis-Menten rate equation constants in a batch enzyme reactor.
Theory:
Batch enzyme reaction system utilization the industrially important glucose isomerization
reaction catalyzed by glucose isomerase. The purpose of the unit is to demonstrate batch enzyme
kinetics and enzyme characteristics. The reaction takes place inside a stirred vessel where the
stirrer itself is a porous basket inside which the enzyme is immobilized.
The BE1 introduces the fundamentals of batch enzyme catalysis. It consists of a bench-top unit
onto which is mounted a reactor vessel in which the glucose isomerase-mediated reaction takes
place. The reactor itself is made of clear acrylic which gives good visibility. A cruciform
geometry impeller constructed from stainless steel mesh retains the immobilized enzyme whilst
allowing efficient mixing with the liquid reactant (glucose solution). The impeller is a variable
speed type. The reaction temperature is maintained using two heaters and a temperature sensor
mounted within the reactor. These are linked to a PID controller which is programmed to
maintain the desired set-point temperature. Safety interlocks prevent the heaters being activated
when there is a low reactor liquid level or when the impeller is inactive.
A continuous sampling loop driven by a peristaltic pump removes liquid from the reactor and
transfers it to a tubular coil heat exchanger where it is cooled prior to passing through a
polarimeter where the angle of rotation of polarized light is measured. From this angle
measurement the concentration of both glucose reactant and fructose product can be determined.
This eliminates the need for manual glucose assays. The measurement system relies on the fact
that both glucose and fructose solutions rotate beams of polarized light, glucose to the right and
fructose to the left. The polarimetry measurement method allows the progress of the reaction to
be monitored on-line.
The polarimeter assembly consists of an elongated optical flow cell mounted between two
polarizing lenses, one of which is fixed (polarizer) and the other being free to rotate (analyzer).
On the outside of the polarizer is a light source and on the outside of the analyzer is a detector
which detects the intensity of emitted light that has passed through both polarizing lenses and the
sample tube. Attached to the analyzer is an angle measurement device. Both the optical
transmission and the angle of rotation are relayed to electronic displays on the control console.
Chemical Reaction:
Glucose Fructose
Procedure:
Prepare the buffer, glucose solutions and enzyme a day before.
Turn on the circuit breaker at rear and on/off switch on front of the unit.
Press the scroll key to get the temperature reading and adjust it using up and down keys.
Set the circulation pump to high for priming. After priming slow down the speed.
Set the reactor temperature to 60°C.
Turn on the water supply to the heat exchanger.
Adjust the hand wheel of Polari meter to an angle of rotation of 0.
Run the experiment after settings.
Polari meter readings should be taken every 3 minutes.
Plot the glucose concentration (µmol/ml) against time (min) and plot a linear regression for the
initial straight line section of the graph. Determine the gradient of the linear regression for
glucose concentration. The gradient is the reaction rate r.
r = KWCS / KM +CS
where:
r = rate (µmoles glucose converted per minute)
k = rate constant (µmoles converted per gram per minute)
W = mass of dry enzyme in the reactor (grams)
CS = reactant (substrate) con (g/ml or mol/litre)
KM = Michaelis-Menten constant (same units as CS)
Plot the reciprocal of the reaction rate against the reciprocal of the starting substrate (glucose)
concentration enables the constants of the Michaelis-Menten equation to be determined from the
intercept and gradient since:
1/r = KM/kWCS +1/kW
Glucose stock solution should be diluted with buffer solution in the ratios given in the table
below:
Glucose
concentration
% w/v
10.0 13.0 20.0 30.0 45.0
Glucose
concentration
% w/w
9.7 12.4 18.7 27.1 35.1
Volume of
glucose stock
(ml)
215 279 430 645 967
Volume of
buffer (ml)785 721 570 355 33
Observations & Calculations:
Cs 1/CsGradient(micromole/ml/min)
r(micromole/min)
1/r
0.215 4.6511 -4.3157 4315.7 0.00023
0.471 2.1231 -6.9215 6921.5 0.000145
From Michaelis-Menton Plot:
Gradient= Km/kW=0.000036
Intercept=kW=0.00007361
As, From above expression:
Km=0.000036×kW
So, Km=0.000036×0.00007361
Km = 2.47×10-9
Raw data for glucose concentration 21.5g/ml:
Temperature(T2)
Specific rotation of Fructose at
T2
Specific rotation of
glucose at T2
RotationConc. of glucose
Time
17.4 -93.9 52.2 58.68 0.223 317.7 -93.6 52.2 58.11 0.223 617.1 -94.1 52.2 59.04 0.220 917.4 -93.6 52.2 59.90 0.219 1217.7 -93.6 52.2 58.92 0.216 1517.8 -93.5 52.2 59.61 0.208 1817.9 -93.6 52.2 58.27 0.202 2117.8 -93.6 52.2 58.47 0.198 2417.8 -93.6 52.2 59.24 0.194 2717.8 -93.5 52.2 58.31 0.187 3017.9 -93.7 52.2 59.33 0.184 3317.8 -93.6 52.2 58.31 0.180 3617.8 -93.6 52.2 58.43 0.177 39
Raw data for glucose concentration 47.1g/ml:
Temperature(T2)
Specific rotation of Fructose at
T2
Specific rotation of
glucose at T2
RotationConc. of glucose
Time
16.2 -94.7 52.3 -1.87 0.009 411.9 -97.7 52.3 -2.64 0.013 813.0 -97.0 52.3 -1.53 -0.007 1218.7 -93.0 52.2 34.63 0.471 1618.9 -92.7 52.2 34.48 0.471 2018.6 -93. 52.2 32.94 0.463 2419.0 -92.7 52.2 33.51 0.466 2819.3 -92.5 52.2 32.12 0.459 3219.4 -92.5 52.2 31.74 0.457 3618.8 -92.4 52.2 30.90 0.453 4018.8 -92.8 52.2 29.48 0.446 4418.9 -92.9 52.2 28.24 0.440 4819.3 -92.7 52.2 26.86 0.433 5219.3 -92.5 52.2 26.86 0.433 5619.3 -92.5 52.2 26.37 0.431 6019.3 -92.3 52.2 26.35 0.430 64