Research Journal of 
Recent 
Sciences 
______
______________________________
______
____
___
 
ISSN 2277
-
2502
 
 
Vol. 
2
 
(
ISC
-
2012
), 
35
-
37
 
(201
3
)
 
Res.J.
Recent
.
Sci.
 
 
 
International Science Congress Association
 
 
 
 
  
35
 
Short Communication 
 
A Step 
t
owards Environmental Protection in Textile Wet Processing
 
 
Shah S.R. and Shah J.N. 
 
Department of Textile Chemistry, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001
,
 
INDIA
 
 
Available online at:
 
www.isca.in
 
Received
 
28
th
 
May
 
2012
, revised
 
28
th
 
December
 
2012
, accepted
 
4
th
 
January
 
201
3
 
 
 
 
Abstract 
 
Environmental awareness is the most often talked subject in today’s industrial and social scene all over the world. In
 
India, 
right now the quantum of problem associated with the effluent by industrial waste is small but with rapid industrialization, 
increases rapidly to a significant level. Chemical processing of textile material is one of the leading consumers of water 
(50 to 
300 liters of water per kg of textile material) and the second biggest effluent generating industry. Among the various wet 
processing steps, pretreatment process, utilize the highest amount of water. Many approaches, namely, development of 
machines/
techniques to reduce liquor consumption, application of green chemicals, biotechnology applications, quality control 
and inventory management, and others have been made to minimize water/effluent minimization. In the present research, the 
two important ste
ps in pretreatment process, namely mercerization of cotton and scouring of synthetic fibers have been 
centralized through water consumption to minimize effluent loads. Both these processes have been performed in the present 
work through the application of 
solvents (no water used). After the said pretreatment processes more than 90% of solvent can 
be recovered and recycled for next processes. The new innovative processes were compared with the conventional processes. 
The results obtained are quite comparable
 
to that of conventional process and encouraging. In future commercialization of 
these processes will be tried.
 
 
Keywords: 
Environment, 
p
retreatment, 
s
olvent, 
t
extiles, 
w
et processing
.
 
 
Introduction 
 
Next to leather, textile industries are leading consum
er of water. 
Cotton fibres required the highest (appx 250 
–
 
350 Kg / Kg of 
fabric) and synthetic fibres the lowest (appx 100 
–
 
200 Kg / Kg 
of fabric) amount of water. The water consumed in processing 
department is about three times than all the other units
 
put 
together and bleaching proces
s, the highest consumer (table
1)
1
-
3
. 
The conventional preparatory processes of textiles namely, 
desizing, scouring, bleaching and washing are highly water and 
energy consuming operations (table
–
2
)
4
. 
 
 
Table
–
1
 
Water consump
tion in textiles units
 
Process
 
Water consumption 
(%) of total
 
Bleaching 
and
 
finishing
 
38
 
Dyeing
 
16
 
Prrinting
 
8
 
Boiler
 
14
 
Humidification (spnning 
and
 
weaving)
 
15
 
Sanitary 
and
 
others
 
9
 
 
Various approaches have been developed in textile processing to 
m
inimize water consumption
5
-
7
.
 
Development of machineries 
having low liquor ratio
. 
Conversion of batch
-
wise process into 
semi
-
continuous/continuous process
. 
Development of chemicals 
/ auxiliaries to improve process efficiency
. 
Application of 
solvent in pret
reatment & other processes
. 
Development in 
washing mechanism such as counter current washing, aquatex 
washing, powerful jets, vibrator washing etc
. 
Reuse and recycle 
of process chemicals / liquor
. 
Many researchers have worked on 
the said principles to mini
mise water usage (and energy usage) 
in pretreatment process. However, very few literatures were 
available pertaining to use of solvent technology in pretreatment 
and mostly all in scattered manner 
8
-
14, 16
. In the present 
research, two important operations
 
of pretreatment namely, 
mercerisation of cotton and scouring of synthetic fibres have 
been performed by using the solvent (No water). The efficiency 
of solvent processes have been compared with that of 
conventional processes. Further, solvents have been r
ecovered 
and reused in next operations and result were analyzed.  
 
 
Table
–
2
 
Consumption of water 
and
 
energy in pretreatment process
 
Process
 
Consumption of 
water
 
(Kg / Kg of Fabric)
 
Consumption of 
steam
 
(Kg / Kg of Fabric)
 
Desaizing
 
3
 
0.25
 
Washing
 
20
 
0.35
 
Couring
 
2
 
1.75
 
Washing
 
20
 
0.30
 
Bleaching
 
2
 
1.00
 
Washing
 
40
 
0.60
 
Total
 
87
 
4.20
 
Research Journal of 
Recent 
Sciences 
______
_
_
_______________________________
______________
_
________
 
ISSN 2277
-
2502
 
Vol. 
2
 
(
ISC
-
2012
), 
35
-
37
 
(201
3
)
 
 
 
Res.J.Recent.Sci
 
  
 
International Science Congress Association
 
 
36
 
 
Material
 
and Method
s
 
The plain woven cotton, polyester and nylon fabrics were 
procured from local textile unit and used throughout the 
experiments (table
–
3
). All the chem
icals used in present 
investigation were of laboratory reagent grade. The details of 
two solvents used in present study ha
ve been reported in table.
 
Table
–
3
 
Specifications of fabrics used
 
Fibre/Specifications
 
Cotton
 
Polyester
 
Nylon
 
Wt (gm) / mt
2
 
125
 
106
 
1
11
 
EPI
 
103
 
66
 
74
 
RPI
 
100
 
57
 
66
 
Stage
 
After 
bleaching
 
Grey
 
Grey
 
 
Table
–
4
 
Specifications of solvents used
 
Solvent / 
Specifications
 
Ammonia
 
Trichloroethylene
 
Chemical formula
 
NH
3
 
C
l
CH=CC
l
2
 
Molecular weight
 
17
 
130.5
 
Boiling Point (
o
C)
 
-
 
33.4
 
86.9
 
Speci
fic gravity (g/cc)
 
0.817
 
1.464
 
 
Mercerization of cotton: 
Cotton fabric was conventionally 
mercerised on laboratory model chain mercerising machine. The 
fabric was padded in sodium hydroxide solution (48 
–
 
52
o
 
Tw) 
at room temperature and given dwell time o
f 45 seconds with 
warp tension. In the solvent mercerisation process, cotton fabric 
was passed through liquid ammonia solution and aged for 45 
–
 
60 seconds with warp tension. In both the processes after 
mercerisation fabric was washed thoroughly to neutral
 
pH with 
distilled water. In solvent process, after mercerisation ammonia 
was recovered and recycled for next operation.
 
 
Scouring of synthetic fibres: 
Polyester and nylon fabrics were 
scoured conventionally using non ionic detergent (1 % w/v) at 
90
o
C for 
30 minutes. In the solvent scouring process, polyester 
and nylon fabrics were treated in solvent (trichloroethylene) at 
50
o
C for 10 minutes. After completion of scouring, solvent was 
recovered by distillation process and reused. After scouring, in 
both the
 
operations, fabric was washed to neutral pH with 
distilled water.
 
 
Analytical procedures
: 
Weight loss percentage of tre
a
ted 
samples were determined by finding the differences in weight of 
sample before and after treatment and always after conditioning. 
We
ttability of sample was determined by standard prescribed 
drop test method. Moisture content, tensile strength and dye 
exhaustion of various samples were determined as per the 
process prescribed earlier 
15
. Swelling of fibre, cross
-
section and 
uniformity o
f reactions were analysed microscopically. Luster 
and feel of various samples were evaluated by subjective test 
method.      
 
Results and 
D
iscussion
 
Mercerization of cotton using ammonia:
 
Cotton fabric was 
mercerized using liquor ammonia (solvent) and comp
ared with 
conventional caustic soda process. The efficiency of 
mercerisation waas determined in terms various parameters 
namely, swelling, cross section, lustre, moisture content, 
dyeability etc and results obtained are reported in table
–
5
.
 
 
Ammonia is a p
owerful and rapid swelling agent for cellulosic 
fibres and reacting mainly on ordered region. The swelling 
reaction in liquid ammonia proceeds at  considerably faster rate 
than in conventional caustic soda treatment. Further, the 
recycled ammonia has also 
comparatively faster rate of swelling 
than conventional process. Liquid ammonia treatment results in 
a smooth and more uniform fibre surface compared to caustic 
soda treatment because of the less compressive strains and 
frictional force in former one. Cott
on fabrics treated by liquid 
ammonia process improved the tensile properties, luster, 
appearance and wrinkle recovery of the materials. Liquid 
ammonia causes swelling of cellulose and can be completed 
recycled. Because of the cyclic nature of this process,
 
there 
would be no pollution, while conventional mercerising using 
caustic soda creates problems of pollution. Moisture absorption 
capacity is related with the porosity of structure. 
 
 
Table
–
5
 
Properties of mercerized cotton after conventional and 
liquor a
mmonia processes
 
Property
 
Caustic 
treated
 
Ammonia 
treated
 
Recycled 
and
 
treated
 
Swelling
 
Slower 
and
 
less
 
Faster 
and
 
high
 
Medium
 
Cross section
 
Round 
and
 
lower 
thickness of 
cell wall
 
Round 
and
 
increase in  
thickness of 
cell wall
 
Round 
and
 
higher 
convoluated
 
Uniformity
 
Poor
 
Better
 
Medium
 
Luster
 
Superior
 
Medium
 
Lower
 
Moisture 
content (%)
a
 
5.71
 
5.84
 
5.74
 
Dye exhaustion 
(%)
b
 
153
 
144
 
139
 
Tensile strength 
(kg/cm)
c
 
4.11
 
4.19
 
4.16
 
Values of untreated fibre a : Moi
sture content = 5.61 %, b : Dye 
exhaustion = 10
0 %,
 
c : Tensile strength = 3.84 kg/cm
 
  
 
Higher moisture content on liquor ammonia mercerization 
indicates increase in porosity of structure. Comparative dyeing 
tests on unmercerized, caustic mercerized and ammonia 
mercerized cotton samples indicated tha
t caustic mercerization 
greatly enhanced dye substantivity compared to ammonia
 
treatment. This may be because the swelling occurs with 
ammonia is mainly in the ordered region while in case of caustic 
soda in both the regions i.e. ordered and disordered and
 
dye 
molecules do not enter in ordered structure. Compared to 
Research Journal of 
Recent 
Sciences 
______
_
_
_______________________________
______________
_
________
 
ISSN 2277
-
2502
 
Vol. 
2
 
(
ISC
-
2012
), 
35
-
37
 
(201
3
)
 
 
 
Res.J.Recent.Sci
 
  
 
International Science Congress Association
 
 
37
 
untreated sample, the liquor ammonia treated sample appears 
rounder but lesser than the conventional treated sample. The 
uniformity of fibrillar structure is better in case of ammonia 
compared t
o caustic soda resulting in improvement of tensile 
strength in higher values. This can be explain as : Liquid 
ammonia process is both ‘Inter fibrilar’ and ‘Intra fibrilar’. The 
differences between caustic soda and liquid ammonia, is in the 
size of penetrat
ing molecules. Ammonia molecules are smaller
 
in size penetrates better in the cellulosic structure and also cross 
links with the parent molecules. However, the boiling point of 
liquid ammonia is 
-
33
o
C and therefore the said process is very 
difficult to ope
rate. This is to be handled very carefully and 
recycled effectively.
 
 
Solvent scouring of synthetic fibres
: 
Scouring of the most 
commonly used synthetic fabrics (polyester 
and
 
nylon) are 
carried out using solvent and conventional methods. The 
efficiency of
 
scouring was evaluated in terms of weight loss 
percentage; wettability, strength loss etc. are reported in table
–
6
.
 
It has been found that (table
–
6
) weight loss percentage is 
slightly higher on both the fibres with solvent in comparison to 
conventional pr
ocess. Further, wettability and dyeability values 
are also improved in solvent scoured samples. This may be due 
to the removal of all the impurities by high penetrating action of 
solvent. No oligomers in polyester have been observed on 
solvent scoured samp
le and feel of fabrics also improved. 
However, tensile strength reduced to higher extent in case of 
solvent scouring process in comparison to conventional process. 
 
 
Important significance of solvent scouring for synthetic 
fibres can summarized as : 
Feel o
f the fabric appears fuller
. 
Complete removal of oligomers from polyester fibre
. 
Lower 
cost of process (as solvent can be recycled)
. 
Better dyeability 
and wetability
. 
Minimum damage to the material
. 
Reduced 
water pollution
. 
Solvents used in textile process
ing are 
inexpensive, readily available, non
-
toxic, non
-
flammable, stable 
to repeated recovery, inert to textiles and non
-
corrosive. The 
main difficulties of solvent scouring are the need for systems to 
recover from fabric after processing. However, the gro
wing 
problems associated with the increasing demand for raw water 
and discharge of effluent have given an impetus to the solvent 
based processing systems.
 
 
 
Conclusion
 
 
Development of solvent based processing techniques of textiles, 
have gained much popula
rity in view of the water shortage in all 
parts of world. Two important steps of pretreatment i.e. 
mercerization of cotton and scouring of synthetic fibres, which 
consume lots of water and toxic chemicals have been examined 
by solvent treatment. It has bee
n safely said that both the 
processes can be satisfactorily carried out with the solvents. The 
outputs of laboratory results are quite compatible to the 
conventional process. Liquor ammonia is the best alternative for 
caustic mercerization for cotton and c
hlorinated solvents to the 
conventional scouring for synthetic fibres. 
 
 
References
 
1.
 
During G, 
Rev Prog Color
, 
(7),
70 
(1976)
 
2.
 
Carbonell J, Egili H 
and
 
Perriy M, 
Amer Dyestuff Rep.
,
 
(44),
 
66
 
(1976)
 
3.
 
Jhala B
.
P
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and
 
Bhatt S
.
R
.
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J Text Asson.
, 33 
(1995)
 
 
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Shah H
.
A
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, Tiwary R
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V
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and
 
Trivedi P
.
K
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19
 
(1987)
 
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Brenner E
.
, 
Melliand Textilberichte
, 
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742
 
(1994)
.
 
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ATIRA Research note, CCT/61, 
(1961)
 
7.
 
Duckworth C
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and
 
Thawites J
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J
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85,
 
225 
(1969)
 
8.
 
Switer S
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and
 
Simpson, 
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, 
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1,
 
35 
(1972)
 
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3(535),
 
156 
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Kolb, AATCC Symposiu
m, Textile Solvent Technology, 
97 
(1973)
 
 
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Goddar, 
 
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, 54
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Bredereck K
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and
 
Saafar A
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Melliand Textilber
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63,
 
510
 
(1982)
 
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Bredereck K
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,
 
Textilveredlung,
 
13,
 
498, 
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Wakida T
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et al., 
Text Res J.,
 
111,
 
154
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Shah S
.
R
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and
 
Shah J
.
N
.
, 
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,
 
61 
(2009)
 
16.
 
Saravanan D.,
 
J Text Asso.
, 
66, 
133 
(2005)
 
 
Table 
–
 
6
 
Scouring of PET and Nylon using solvent and conventional process
 
 
Properties
 
Polyester
 
Nylon
 
Grey
 
Solvent 
treated
 
Conventional
 
treated
 
Grey
 
Solvent 
treated
 
Conventional
 
treated
 
Weight loss (%)
 
-
 
4.13
 
3.71
 
-
 
4.28
 
3.76
 
Absorbency (Sc)
 
�180
 
4
 
6
 
� 180
 
3
 
6
 
Dye exhaustion (%)
 
100
 
140
 
128
 
100
 
151
 
136
 
Feel
 
Harsh
 
Fuller
 
Medium
 
Harsh
 
Better
 
Medi
um
 
Cost (per/kg)
 
-
 
X
 
1.8 X
 
-
 
X
 
2.1 X
 
Oligomers
 
High
 
No
 
Medium
 
-
 
-
 
-
 
Strength (kg/cm)
 
7.34
 
6.12
 
6.86
 
7.10
 
6.31
 
6.52
 
 
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