DYES: ENVIRONMENTAL IMPACT AND
• Guided by:
• Prof.- G.S. Bramha
• Prof.- Sri Lalitha
• Prof.- Renu Rani
Avinash Kr. Singh
• What is a dye?
• Types of dyes
• Impacts of dyes on environment
• Harmful effects of dyes
• Remediation measures
What is a Dye?
• A natural or synthetic substance used to add a
color to or change the color of something. Such
substances with considerable coloring capacity
are widely employed in the in the production of
consumer products, including paints, textile,
printing inks, pharmaceutical, food, cosmetics,
plastics, photographic and paper industries.
Types of dyes
Types of dyes
1. Natural dyes
2. Synthetic dyes
3. Food dyes
5.Other dyes like leather, laser
And also based on chemical classification With respect to
the number and production volumes, azo dyes are the
largest group of colorants, constituting 60-70% of all organic
dyes produced in the world.
• They have a wide range of applications in the textile, pharmaceutical and
cosmetic industries, and are also used in food, paper, leather and paints
• At present, India contributes about 6% of the share in the global market with a
CAGR of more than 15% in the last decade.
• The dyeing process in various industries has garnered a lot of attention lately
because of the emerging concept of sustainability and eco-friendly variants.
• Till the midst of nineteenth century all the dyes used for textile products were
• The textile industry is accountable for using and producing 1.3 million tons of dyes
and pigments, most of which are made synthetically.
• The textile industry is one of the largest sectors globally and produces an
astonishing 60 billion kilograms of fabric annually, using up to 9 trillion gallons of
• Heavy metals in the colorants used in printing industry has severe effects on the
• For example, titanium oxide, chromate, molybdenum, and iron are used as
pigments; titanium oxide is used for pearlescent pigments; and aluminum and
brass are used in metallic inks.
• Ink is a liquid or paste that contains
pigments or dyes and is used to color a
surface to produce an image, text, or
design. Ink is used for drawing or writing
with a pen, brush, or quill.
Air pollution –
• Most processes performed in textile
mills produce atmospheric emissions.
Gaseous emissions have been
identified as the second greatest
pollution problem (after effluent
quality) for the textile industry.
• Speculation concerning the amounts and types of air pollutants emitted from
textile operations has been widespread but, generally, air emission data for
textile manufacturing operations are not readily available.
• Air pollution is the most difficult type of pollution to sample, test, and quantify
in an audit.
• The wastewater from textile plants
is classified as the most polluting of
all the industrial sectors,
considering the volume generated
as well as the effluent composition
• In addition, the increased demand for textile products and the proportional
increase in their production, and the use of synthetic dyes have together
contributed to dye wastewater becoming one of the substantial sources of severe
pollution problems in current times.
• Dyes can remain in the environment for an extended period of time, because of
high thermal and photo stability to resist bio degradation..
HARMFUL EFFECTS OF DYES
o Dyes absorb and reflect sunlight in water. This diminishes photosynthetic activity
of algae and seriously influences the food chain.
o Many dyes and their breakdown products are carcinogenic, mutagenic and/or
toxic to life.
o Triple primary cancers involving skin, kidney, urinary bladder and liver of dye
workers have been reported.
o Textile dyes can cause allergies such as contact dermatitis and respiratory
diseases, allergic reaction in eyes, skin irritation, and irritation to mucous
membrane and the upper respiratory tract.
• Certain reactive dyes causes respiratory sensitization of workers who are
occupationally exposed to them.
• The presence of very small amounts of dyes in the water, seriously affects the quality
and transparency of water bodies such as lakes, rivers and others, damages the
• The highly toxic and mutagenic dyes decrease light penetration and photosynthetic
activity, causing oxygen deficiency and limiting downstream beneficial uses such as
recreation, drinking water and irrigation.
• Azo dyes have toxic effects, especially carcinogenic and mutagenic. They enter the
body by ingestion and are metabolized by intestinal microorganisms causing DNA
o Enhance the existing effluent disposal treatment plants through Reverse
Osmosis (RO) and the resultant water can be used as fresh water for the
o Industries should switch over to Cleaner Production Technologies (CPT) by
using combination of soft flow machines, low salt dyes and membranes
filtration. This effectively reduces the water consumption by 50%.
o Use of activated carbon in the absorption of chemicals in waste from the
dye process, which has shown to greatly reduce some of the pollutants in
o Dye fed silk worms' take silk farming to the next level:
Researchers have come up with a process wherein by adding a chemical dye to
the diet of the silkworms, cocoons are produced in bright; luminous hues. The
process is expected to eliminate the requirements of conservative dyeing such as
huge volumes of water. It would to result in restricting water and environmental
o Air Dyeing Technology is a dyeing process that
uses air instead of water to dye garments,
allowing companies to create garments with
vivid designs and colors, without polluting the
water and environment.
• It uses 95 percent less water.
• Emits 84 percent less Green House Gases
• Requires 87 percent less energy
o Ultrasound-assisted textile dyeing: Ultrasound-assisted textile dyeing was first
reported by Sokolov and Tumansky in 1941.
The use of ultrasonic energy has been widely studied in terms of improving washing
fastness.Ultrasonic energy can clean or homogenize materials, accelerating both
physical and chemical reactions, and these qualities can be used to improve textile
• The Dyestuffs Manufacturers Association of India, popularly known as DMAI
was set up in 1950, to promote and protect trade, commerce . The organization
needs to promote environment concerns of this industry and the ways to
• An alternative to minimize the problems related to the treatment of textile
effluents would be the development of more effective dye that can be fixed fiber
with higher efficiency decreasing losses on tailings waters and reducing the
amount of dye required in the dyeing process
• Moral outrage will not convince many leading manufacturers to change their
ways; as long as companies do not pay a price for the land and water their
suppliers poison, the excessive use and abuse of environmental parameters like
air and water to dye products will continue.