1. الرحيم الرحمن ا بسمالرحيم الرحمن ا بسم
In the Name of Allah, the MostIn the Name of Allah, the Most
Beneficent, the Most Merciful.Beneficent, the Most Merciful.
2. 2
A New Method for Carboxymethylation of
Starch at Mild Conditions
M.A. ElSheikh
National Research Centre, Textile Research Division,
El-Tahrir St., Dokki, Cairo, Egypt, postal code 12311.
E-mail: manal_elsheikh@yahoo.com
4. 4
The textile industry is one of the most
important industries in Egypt.
Unfortunately, the CMS used in the
Egyptian textile industry is not a local
product. The need to produce a local CMS
with lower costs for use in the textile
industry, as a substitute for imported CMS,
was the motive behind the current work.
5. 5
What is new?What is new?
Carboxymethyl starch was first
synthesized in 1924.
Many reports and patents have
been published on the preparation
and manufacture of CMS.
6. 6
In this work, a new method
has been adopted and used to
produce a high quality CMS
product at mild condition.
7. 7
Carboxymethylation took place at room
temperature (30o
C)
Mild reaction conditions were employed.
Little concentrations of etherifying agents were
applied.
All the reactions took place without stirring
during the reaction course.
Simple apparatus for the carboxymethylation
process was used.
However:
A 100% reaction efficiency and a completely cold
water soluble product with a clear and
transparent solution were obtained.
9. 9
Optimization
Factors affecting the reaction
•Reaction time
•Catalyst concentration
• Sequence of addition
•Cooling during the addition
•Material : liquor ratio
•Ethanol: water ratio
•Type of solvent
Characterization
•Degree of substitution (DS)
•Reaction efficiency (E%)
•Reproducibility
•Different kinds of starch
•Solubility
•Apparent viscosity
•Rheological properties
•Transparency
•Sizing and desizing
•Tensile strength
•Elongation at break
Utilization
As sizing agent
for cotton fibers
10. 10
Carboxymethylation
A certain amount of maize starch was placed in sealable bottle
and mixed together with a known volume of the solvent.
An aqueous solution of sodium hydroxide was added drop
wise to the starch-solvent mixture under stirring until the
whole amount of sodium hydroxide was added. The sodium
salt solution of monochloroacetic acid prepared by the
reaction of monochloroacetic acid with sodium carbonate
monohydrate was added drop wise to the starch-solvent-
sodium hydroxide mixture under continuous stirring until
complete addition of the sodium monochloroacetate
solution. Stirring was then stopped and the bottle was
closed and kept at 30o
C for certain reaction time. After
carboxymethylation, the CMS samples were washed with
ethanol : water solution (80:20) while excess alkali was
neutralized using acetic acid. After washing, the CMS
samples were filtered, oven dried at 100o
C.
11. 11
Mechanism of the reaction
The carboxymethylation process could be considered by
the following three reactions:
NaOH
2ClCH2COOH +Na2CO3.H2O 2ClCH2COONa + CO2+ 2H2O (1)
St-OH + ClCH2COONa St-OCH2COONa + NaCl + H2O (2)
NaOH + ClCH2COONa HO-CH2COONa + NaCl (3)
12. 12
Chloroacetic acid, sodium
carbonate and sodium hydroxide
were used in equivalent molar
ratios (0.2 mole/mole starch). An
alkali metal hydroxide catalyst was
used to accelerate the
carboxymethylation reaction at
room temperature.
13. 13
Factors Affecting the Carboxymethylation
Reaction Expressed as DS and E%
solvent type
Ethanol : water ratio
M:L ratio
Cooling
Catalyst concentration
Reaction time (seven days)
Reaction time (50 h)
DSandE%
0.2, 100%
0.1989, 99.36%
0.185, 93%
0.185, 93%
0.172, 86%
0.1375,68.75%
0.068, 34.2%
14. 14
Rate of Carboxymethylation Reaction (Effect of
Reaction Time)
1. DS, reaction efficiency and rate constant
after 50 hours (Figure 1 (a and b)). DS= 0.068
and E%=34.2% were obtained after 50
hours. Rate constant = 0.00724.
2. DS, reaction efficiency and rate constant
after seven days (Figure 2 (a and b)). DS=
0.1375 , and E%= 68.75% were obtained
after 50 hours. Rate constant = 0.00466.
15. 15
[ClCH2COONa]
and [NaOH]:
0.2 mole/mole
St.; Temp.:
30o
C; Time:
0-50 h; M:L
ratio: 1:2.5;
EtOH:H2O
ratio:70:30;
Sequence: I;
No cooling.
Figure 1(a): Rate of carboxymethylation reaction within the first fifty
hours
0
0.02
0.04
0.06
0.08
0 10 20 30 40 50 60
Time (h)
Degreeofsubstitution
-4
1
6
11
16
21
26
31
36
ReactionEfficiency(%)
DS Reaction Efficiency
Figure 1(b): Carboxymethylation rate
constant within the first fifty hours
y = -0.0031x - 0.731
-1.5
-1
-0.5
0
0 10 20 30 40 50 60
Time (h)
log(a-x)
correlation coefficient = 0.996
Slpoe = -0.00314
k1 = 0.00724
16. 16
Figure 2(a): Rate of carboxymethylation within seven days
0
0.04
0.08
0.12
0.16
0 24 48 72 96 120 144 168 192
Time (h)
Degreeofsubstitution
-5
5
15
25
35
45
55
65
75
ReactionEfficiency(%)
DS E%
Figure 2 (b): Carboxymethylation
rate constant within seven days
y = -0.002x - 0.8569
-1.5
-1
-0.5
0
0 50 100 150 200
Time (h)
log(a-x)
correlation coefficient = 0.954
Slpoe = -0.00202
k = 0.00466
[ClCH2COONa]
and [NaOH]:
0.2 mole/mole
St.; Temp.:
30o
C; Time:
0-168 h; M:L
ratio: 1:1.5;
EtOH:H2O
ratio:70:30;
Sequence: I;
No cooling.
17. 17
Effect of catalyst
concentration
DS of 0.172 with reaction efficiency of 86%
was obtained after 24 hours of
carboxymethylation using 0.3 mole/mole
St. of catalyst.
19. 19
Sequence of Addition and
Cooling During Addition
sequence I (solvent then starch then sodium
hydroxide then catalyst then ClCH2COONa),
sequence II (solvent then sodium hydroxide then
catalyst then starch then ClCH2COONa) and
sequence III (solvent then sodium hydroxide
then catalyst then ClCH2COONa then starch).
Regardless of the sequence of addition, the DS
and the reaction efficiency were about 0.185
and 93% respectively.
The increase in the DS and the reaction efficiency
is certainly due to the cooling effect.
20. 20
Figure 4: Effect of cooling and sequence of addition on the degree
of substitution and the reaction efficiency
0
0.05
0.1
0.15
0.2
I II III
Sequence of addition
Degreeofsubstitution
0
25
50
75
100
ReactionEfficiency(%)
DS
E%
[ClCH2COONa]
and [NaOH]:
0.2 mole/mole
St.; [catalyst]:
0.3 mole/mole
St; Temp.:
30o
C; Time:
24 h; M:L
ratio: 1:1.5;
EtOH:H2O
ratio:70:30;
Sequence: I,
II and III;
Cooling.
21. 21
Material : Liquor Ratio
1:1.5 constitutes the optimal material :
liquor ratio. Maximum DS and reaction
efficiency obtained at this point were
0.185 and 93% respectively.
22. 22
Figure 5: Effect of material : liquor ratio on the degree of substitution
and the reaction efficiency
0
0.05
0.1
0.15
0.2
1:1 1:1.5 1:2 1:2.5 1:3
Material : Liquor ratio
Degreeofsubstitution
0
25
50
75
100
ReactionEfficiency(%)
DS
E%
[ClCH2COONa]
and [NaOH]:
0.2 mole/mole
St.; [catalyst]:
0.3 mole/mole
St; Temp.:
30o
C; Time: 24
h; M:L ratio:
1:1- 1:3;
EtOH:H2O
ratio:70:30;
Sequence: I;
Cooling.
23. 23
Ethanol : Water Ratio
• Maximum DS and reaction efficiency
were obtained at an ethanol : water ratio
of 90:10 (0.1989 and 99.36%
respectively).
24. 24
Figure 6: Effect of ethanol : water ratio on the degree of substitution and
the reaction efficiency
0
0.05
0.1
0.15
0.2
50:50 60:40 70:30 80:20 90:10
Ethanol : Water ratio
Degreeofsubstitution
0
25
50
75
100
ReactionEfficiency(%)
E%
DS
[ClCH2COONa] and
[NaOH]: 0.2
mole/mole St.;
[catalyst]: 0.3
mole/mole St;
Temp.: 30o
C; Time:
24 h; M:L ratio:
1:1.5; EtOH:H2O
ratio:50:50-90:10;
Sequence: I;
Cooling.
25. 25
Type of Solvent
• The highest DS and reaction efficiency was achieved
with isopropanol and the lowest with propylene glycol.
• The DS and reaction efficiency using the
aforementioned solvents follow the descending order:
• Isopropanol > Ethanol > Tertiary butanol > Methanol >
Propylene glycol
• A DS of 0.2 and a reaction efficiency of 100% were
finally obtained using isopropanol as the solvent. The
use of isopropanol led to a 100% reaction efficiency
while the use of ethanol led to a 99.36% which is an
excellent results for both. This means that both
isopropanol and ethanol can be used efficiently for the
carboxymethylation o starch.
26. 26
Figure 7: Effect of type of solvent on the degree of substitution and the
reaction efficiency
0
0.05
0.1
0.15
0.2
MeOH EtOH Isopropanol Tert. butanol Propylene
glycol
Type of Solvent
Degreeofsubstitution
0
25
50
75
100
ReactionEfficiency(%)
DS
E%
[ClCH2COONa] and
[NaOH]: 0.2
mole/mole St.;
[catalyst]: 0.3
mole/mole St;
Temp.: 30o
C; Time:
24 h; M:L ratio:
1:1.5; Solvent:H2O
ratio:90:10;
Sequence: I;
Cooling.
27. 27
Optimum Conditions
• Optimum conditions for attaining a DS of 0.2 and a
reaction efficiency of 100% were:
• Concentration of ClCH2COONa: 0.2 mole/mole St.,
• Concentration of NaOH: 0.2 mole/mole St.,
• Concentration of Catalyst: 0.3 mole/mole St,
• Carboxymethylation temperature: 30o
C,
• Carboxymethylation time: 24 hours,
• Material : liquor ratio: 1:1.5,
• Solvent :H2O ratio: 90:10,
• Sequence of addition: Solvent then sodium hydroxide
then catalyst then starch then ClCH2COONa,
• Cooling: Cooling during addition of the reactants.
28. 28
The importance of catalyst in the
carboxymethylation process
• Maximum DS and reaction efficiency of
the CMS produced in the presence and in
the absence of catalyst were 0.1923 and
96.14% versus 0.1078 and 53.88%
respectively.
• The rate constants of carboxymethylation
reactions in presence and in absence of
catalyst were 0.0867 and 0.0288
respectively.
29. 29
Figure 8 (a): Rate of carboxymethylation in presence and in
absence of catalyst
0
0.04
0.08
0.12
0.16
0.2
0 5 10 15 20 25 30
Time (h)
DegreeofSubstitution
0
25
50
75
100
ReactionEfficiency(%)
DS (catalyst) DS (no catalyst)
E% (catalyst) E% (no catalyst)
Figure 8 (b): Carboxymethylation rate constant in presence and
in absence of catalyst
y = -0.0376x - 1.3174
y = -0.0125x - 0.7641
-3
-2.5
-2
-1.5
-1
-0.5
0
0 5 10 15 20 25
Time (h)
log(a-x)
catalyst
no catalyst
correlation coefficient =0.92798
Slpoe = -0.03764
k =0.0867
correlation coefficient =0.9632
Slpoe = -0.0125
k =0.0288
31. 31
Type of starch
The high values of DS and reaction efficiency reveal that
the carboxymethylation process is suitable for different
kinds of starch under the set of reaction conditions used.
Table 2: Type of Starch
Type of
starch
Theoretical
DS
Practical
DS
Reaction
Efficiency (%)
Maize 0.2 0.2
100
Rice 0.2 0.1938
96.9
Potato 0.2 0.1984
99.2
32. 32
Characterization of CMS
produced
The results obtained from the tensile strength
and elongation at break of the light cotton fabric
sized with CMS under test reveals the suitability
of this CMS as a sizing agent.
Desizing efficiency of 98% at 30o
C (Table 3) is
another evidence of the suitability of CMS under
test as a sizing agent where the size is removed
efficiently using mild conditions.
33. 33
Practical DS 0.2
Reaction efficiency 100%
Solubility in cold water
(pH=7)
soluble
% Transmittance (0.1%)
aqueous solution
97%
Viscosity at 516 s-1
(mPa s)
(pH=7(
NS
CMS
350
198.3
Rheological properties non-Newtonian pseudoplastic fluid
Sizing
• Control
• Sized with cooked CMS
Desizing efficiency
% of size removal at 30o
C
Tensile strength )
kg(
30.8 kg
42.7 kg
98%
Elongation at break
(%)
7
5.9
Table 3: Major properties of CMS produced
34. 34
CONCLUSION
The new carboxymethylation method produced
CMS with DS of 0.2 and reaction efficiency of
100% using 0.2 mole of both ClCH2COONa and
NaOH /mole St., 0.3 mole catalyst /mole St., M:L
ratio: 1:1.5, isopropanol:H2O ratio: 90:10,
cooling during addition of the reactants, for 24
hours at 30o
C. The new carboxymethylation
process was found reproducible and suitable for
different types of starch. The CMS produced
was cold water soluble giving a transparent
solution with viscosity of 198.3 mPa s at shear
rate of 516 s-1
. The CMS produced was suitable
for use as sizing agent.
