Authors: Sujal Sandeep
Patani, Soham Koik, Pakshal Porwal, Darshan Ganesh Shahane
Guided by: Prof. Dr. Y.M.
Indi
D.K.T.E.
Society’s Textile and Engineering Institute, Ichalkaranji
Highlight/Abstract:
This article investigates
the potential of directly dyeing 100% cotton fabric for dark shades using
reactive dyes without undergoing conventional pre-treatment processes like
scouring, bleaching, and mercerization. The process utilizes cationization of
cotton fabric with keratin hydrolysate, aiming to save energy, time, and reduce
production costs while maintaining color brilliancy. A comparison between the
cationized dyeing process and the conventional dyeing process is also presented,
focusing on washing and rubbing fastness.
Introduction
In the textile industry,
traditional dyeing processes for cotton fabrics often require several
preparatory steps, including scouring, bleaching, and mercerization, which
consume significant amounts of energy and water. With increasing concerns
regarding environmental sustainability and energy conservation, there is a
growing need to explore alternative methods that reduce water and energy
consumption, while still achieving high-quality results.
One promising method for
achieving this goal is the cationization of cotton fabric. Cationization refers
to the process of modifying cotton fibers to carry positive charges on their
surface, which can interact more easily with negatively charged dye molecules, especially
reactive dyes. This article explores the possibility of directly dyeing cotton
fabric for dark shades using reactive dyes through the cationization of cotton
with keratin hydrolysate, thereby eliminating the need for intermediate
pre-treatment processes.
Objective
The primary objective of
this study is to examine whether it is feasible to directly dye 100% cotton
fabric for dark shades using reactive dyes without the need for scouring,
bleaching, and mercerization. The key aims of this modified dyeing process are:
- To analyze the washing and rubbing fastness of cationized cotton fabric and compare them to samples dyed via conventional methods.
- To minimize the use of intermediate pre-treatment processes.
- To reduce energy consumption and production costs.
- To achieve a similar brilliancy of dark shades as conventional methods.
- The study is driven by the need to conserve water and energy, as well as reduce overall production costs in textile manufacturing.
Methodology
Cationization of Cotton with
Keratin Hydrolysate
Cotton fibers are primarily
made up of cellulose, which contains hydroxyl groups (-OH) that are reactive
and can form bonds with other molecules. Keratin hydrolysate, derived from
wool, contains positively charged amino groups (-NH₃⁺ or -NR₄⁺), which can bond with the
negatively charged hydroxyl
groups on cotton fibers. The ionic interaction between these positively charged
keratin hydrolysate molecules and the negatively charged cellulose fibers leads
to the formation of a cationic cotton fiber, which is more receptive to anionic
dyes such as reactive dyes.
The cationization reaction
can be described as follows:
Cellulose-OH + Keratin-NH₃⁺ → Cellulose-O-NH₃⁺
This reaction results in a
modified cotton fiber with a positive charge on its surface, making it more
suitable for binding with anionic dyes.
Dyeing of Cationized Cotton
Once the cotton is
cationized, it can be dyed with reactive dyes, which typically carry a negative
charge due to the presence of sulfonate (-SO₃⁻) or
carboxyl (-COO⁻)
groups. The positive charge on the cationized cotton fibers attracts the
negatively charged dye molecules, resulting in electrostatic interactions
between the fiber and the dye. This interaction forms an ionic bond between the
cotton fiber and the dye.
The dyeing reaction can be
described as:
Cellulose-O-NH₃⁺ + Anionic Dye-SO₃⁻ → Cellulose-O-Dye (ionic
bond)
This reaction ensures that
the dye is effectively fixed onto the cotton fibers, achieving a stable and
durable color.
Extraction of Keratin
Hydrolysate
Keratin hydrolysate is
extracted from wool by treating it with caustic soda (NaOH) under controlled
conditions. The extraction process involves hydrolyzing the keratin protein,
breaking it into smaller peptides, which can then be modified to carry cationic
groups. The extraction process is optimized for maximum yield by adjusting
parameters such as temperature, extraction time, and the concentration of
caustic soda.
The optimal conditions for
keratin extraction were determined using a Taguchi design of experiments, which
tested different combinations of temperature, time, and concentration. After
extraction, the keratin hydrolysate solution was filtered and stored for use in
the cationization process.
Results and Discussion
Fastness Properties
After dyeing the cationized
cotton samples with reactive dyes, several fastness properties were tested,
including washing and rubbing fastness. The results were compared to
conventional cotton dyeing methods that involved scouring, bleaching, and
mercerization.
The washing fastness of the
cationized cotton samples was found to be comparable to the conventional
samples, with minimal color fading or bleeding. Similarly, the rubbing fastness
of the cationized samples was also satisfactory, demonstrating that the
modified dyeing process did not compromise the durability of the fabric.
Color Brilliancy
The color brilliancy of the
dark shades achieved through cationization was evaluated in comparison with the
conventional method. The results indicated that the cationized cotton samples
exhibited similar color depth and brilliancy to those produced through
conventional dyeing processes. This suggests that cationization can effectively
facilitate the direct dyeing of cotton fabric without sacrificing color
quality.
Environmental and Economic
Benefits
One of the significant
advantages of the cationization process is the reduction in the need for
intermediate pre-treatment steps. Traditional cotton dyeing processes require
scouring, bleaching, and mercerization, which consume large amounts of water
and energy. By eliminating these steps, the cationization process reduces water
and energy consumption, leading to environmental and economic benefits.
Additionally, the
cationization process can help reduce the cost of production by minimizing the
number of chemical treatments and reducing the need for salt, which is often
used in conventional dyeing processes. This saltless dyeing process not only
saves on chemical costs but also helps mitigate the environmental impact of salt
discharge into wastewater.
Conclusion
The study successfully
demonstrates that it is possible to directly dye 100% cotton fabric for dark
shades using reactive dyes through the cationization of cotton with keratin
hydrolysate. The cationized cotton fabric exhibited comparable washing and
rubbing fastness to conventionally dyed fabrics, while maintaining similar
color brilliancy. Furthermore, the process offers significant environmental and
economic advantages by reducing water and energy consumption, as well as
eliminating the need for intermediate pre-treatment steps.
This research opens up new
possibilities for energy-efficient, cost-effective, and environmentally
sustainable dyeing processes in the textile industry. Future studies could
explore the scalability of the process and its applicability to a wider range
of dyeing applications.
References:
- AKTEK, T. & MILLAT, A. M. 'Salt Free Dyeing of Cotton Fiber A Critical Review", International Journal of Textile Science, 6, 21-33(2017)
- CHATTOPADHYAY. D. "Cationization of cotton for low salt or salt free Dyeing".2001
- Peter I Hauser Energy - water pollution reduction with fibre reactive dyes and cationized cotton.
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