What is enzymatic Desizing? Effect of temperature on enzymatic desizing :
 |
| Enzymatic Desizing |
Enzymatic desizing uses enzymes to remove the size which was applied
on the fabric. Enzymes are high molecular weight protein biocatalysts. These
can be extracted from animals, plants or bacteria. They are specific in action.
Title:
To observe the effect of temperature on
enzyme desizing of 100% cotton fabric.
Abstract:
In this experiment we were having the task to
perform enzymatic desizing of fabric sample at different temperature
that was presented to us .The fabric samples were provided to us which had
different weights respect to each other and we have to undergo the process of
enzymatic desizing for each of them with change in amount of temperature
applied. The desized fabric after experiment was related with griege fabric
sample ton relate absobancy. Tegewa rating was checked and hand feel for each
sample respect to griege fabric was also observed.
Introduction:
Desizing is the process wherein the size
carried out to the warp yarn earlier than weaving is removed to facilitate the
penetration of dyes and chemical substances within the subsequent wet
processing operations. In the system of desizing, not only sizing agents,
however additionally a few natural impurities are eliminated from fibres. In
desizing, the starches and polymers which are applied which are insoluble, are
transformed into water soluble compound to ease of their elimination. Desizing
of cotton material may be achieved by way of bodily, chemical or combination of
physical and chemical mechanism, specifically rot steeping, acid steeping,
remedy with enzyme and oxidizing agents.
Desizing has the following types:
·
Enzymatic desizing of starches on
cotton fabrics
·
Oxidative desizing
·
Acid desizing
.
Acid Desizing :
In this approach cotton fabric is dealt with with dilute sulfuric acid with a awareness of 5-10 g/1 at a temperature of approximately 40oC for 3-4 hrs. Dilute acid attacks the polymer chain of starch and due to chain cleavage of starch molecule brief water soluble or dispersible chain segments are shaped. The degraded starch is eliminated from the cloth by means of everyday washing remedy.
Enzymatic Desizing:
This experiment was done by the process of enzymatic
desizing. Enzymatic desizing uses enzymes to remove the size which was applied
on the fabric. Enzymes are high molecular weight protein biocatalysts. These
can be extracted from animals, plants or bacteria. They are specific in action.
The processes performed through enzymes are more environmentally friendly. The
enzymes used for starch degradation are amylases hydrolyzing the starch into
water soluble product. Moreover, the amylases have no effect on cotton
structure. Enzymes are very sensitive to temperature and pH so while working
with enzyme one should keep in mind this point.
Enzymatic desizing is much more better than the other two
of the desizing procedures because firstly it is very fast as compared to acid
and rot desizing and secondly it is environment friendly and last but not the
least as compared to acid no damage is done to the fabric.Thats why enzymatic
desizing is by far the mostly used method in industries.
Oxidative Desizing:
In oxidative desizing the risk of damage to the cellulose
fiber is very high and its use for desizing is increasingly rare. Oxidative
desizing uses potassium or sodium per sulfate or sodium bromate as an oxidizing
agent
Materials and Method:
Materials:
- Sized 100% cotton fabric
- Distilled water
- Wetting agent = 2g/l
- Enzyme (Rucolase EPE 124) = 2, 4 g/l
- Liquor Ratio = 1:50
- PH = 6.5
- Temperature = 90⸰c
- Time = 45 mints
Desizing Procedure:
First of all 5 samples of 100% sized cotton fabrics
were taken.The Samples were weighted on weighing balance. According to liquor
ratio 1:50, distilled water was added to steel container. Calculated enzyme
concentrations and wetting agent concentrations were added to those containers
separately and set the pH according to given pH
by adding given acid and base in the solution separately. Cotton fabric
samples were dipped in container and heated in water bath at 90˚C for 45
minutes. Continuous stirring was performed for efficient desizing. Then the
samples were further rinsed in cold water. The rinsed desized fabric samples
were dried in oven at 120˚C for 5-6minutes.
Characterizations:
Hand Feel:
Took a sample of textile fabric and felt the surface of
fabric with the help of index fingers and thumb before and after scouring
process. The sized and desized fabrics were felt by hand to check softness and
variation after desizing at different enzyme concentrations.
- Weight loss:
Weight loss is defined as the amount of weight loss
after the removal of sized material. The weight of cotton sample were measured
at the start and the after the removal of starch were again measured and weight
loss was calculated.
W1 = weight before desizing
W2 = weight after desizing
Weight loss % =
- Tegewa rating
Drop of potassium iodide solution on desized samples were rubbed. The
color variation was checked with TEGEWA color table.
- Water Absorbency:
A drop of water was dropped on sample before desizing
and samples after desizing. Time was noted for water drop absorbed into sample
and was compared with the griege fabric..
Results and Discussion:
The fabric loss the weight after desizing
process because the natural coloring matter and any other colouring matter is
removed from natural fibers that is why the fabric loss it’s weight after
process.
Weight loss%:
Table 1 Effect of temperature concentration on weight
loss
Temperature (⸰C)
|
Weight loss%
|
40
|
8.9
|
50
|
12.9
|
60
|
10.8
|
80
|
9.4
|
90
|
12.92
|
Figure 1 Effect
of temperature on the weight loss of
fabric during de-sizing
The table shows that with increase in temperature the
desizing efficiency also increase that’s why sample that was desized at 90⸰C
has hight weight loss. It’s mean it’s good desized than that of other samples.
Table 2 Tegeva Rating:
Temperature (⸰C)
|
Tegava rating
|
40
|
5
|
50
|
6
|
60
|
4
|
80
|
7
|
90
|
7
|
Figure 2 Tegewa rating of fabric samples
Table (2) and Figure
(2) present the Tegewa ratings of the samples of fabric. Higher the de-sizing
of a sample higher the value of Tegewa. Tegewa ratting increase with increase
in temperature . at 90⸰C temperature highest the value of Tegewa than that of other samples.
Hand feel:
Hand feel of the
de-sized fabric was soft as compared to that of gray fabric. Sample e was
having the softest hand feel as compared to other samples because large amount
of sizing material was removed from it due to a relatively change in
concentration of pH used in it.
Water Absorbency:
This water absorbency test shows that by changing the temperature of the solution the time it takes to absorb water were
different.
Table 3 Effect of temperature on
absorbency
Temperature (⸰C)
|
Time Taken(sec.)
|
40
|
8
|
60
|
3
|
70
|
2
|
80
|
0.89
|
90
|
0.7
|
Table show that at 90⸰C the
time of water absorb is less than that of other temperatures.
Conclusion:
The conclusion we draw from whole of this practical was
that in the enzymatic desizing process by increase in temperature of the
solution the desizing efficiency also increase. Desizing at 90⸰C temperature is
good than that of other samples which were desized at lower temperature from 90⸰C
. Because at 90⸰C enzyme is active and it helps to degradation of starch.
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