This document discusses natural dyes and their extraction process. It provides information on various plants used for natural dye extraction in India and the colors they produce. It also describes different extraction methods like aqueous, alkali, acid, microwave and ultrasonic assisted, solvent and supercritical fluid extraction. Key steps involved in natural dye production include collecting plant materials, testing for color content, drying, size reduction, extraction of coloring components, drying of dye obtained, and packing. Analytical techniques mentioned for identification of dyes include HPLC, LC-MS and spectrophotometry.

1. D.ANNISH JENEFA
B.Sc., Hort.
Lecture Number : 34

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• A dye is a highly coloured substance used to impart colour to an
infinite variety of material like textiles , paper , wood , varnishes ,
leather , ink , foodstuff , cosmetics , medicine etc.,

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• These days environmental protection has become a challenge for the textile
industry because it utilizes lot of chemical for colouration of textile materials.
• These chemicals are harmful for both human as well as environment.
• There is a wide range of natural products in India as it is one of the 17 mega
diverse countries.
• India is well known country of colours as it harbours a wealthy and beautiful
floral resourses

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• Dyeing time
• Temperature
• Liquor ratio
• pH
• Dyeing method
• Mordant and dye concentration (lightness and darkness of the dye)

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• Natural dyes require an element to create a bond between fabric and dye
particle.
• The Mordant is known as the element which can facilitate chemical reaction
taking place between textile fibre and dye.
• As a result , the dye is absorbed into the textile material.
• A Mordant is utilised to fix the dye to fabric and to incorporate colour fastness.

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Metallic mordants
• Metal salts of chromium,
iron, aluminium, cupper,
tin
Oil mordants
• Turkey red oil
Natural mordants
• Tea leaves
• Myrobola
• vinegar

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MORDANT EFFECT
Alum Brightens the colour obtained from a dye source.
Iron/Copper Darkens/saddens hues , produces blacks , brown , grey.
Copper vitriol Improves likelihood of obtaining a green hue.
Tin Produces bright colours especially yellow , orange , red.
Chrome Highly toxic – should not be used for dyeing at home.

8. Flowers used for dye extraction
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Tagetes erecta
• Yellow colour
• Cotton and silk fabrics
• Alum and copper sulphate

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Spathodea campanulata
• Red colour
• Cotton and silk fabrics
• Myrobolan , alum

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Rosa sp.
• Pink,Yellow
• Cotton,silk,wool fabrics
• Ferrous sulphate,Stannus choride

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Chrysanthemum morifolium
• Pink,red,dark purple
• Cotton , silk fibres
• Copper sulphate

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Nerium oleander
• Pink
• DSSC

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Hibiscus rosa-sinensis
• Red
• Camel wool
• alum

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Ixora coccinea
• Red
• Cotton
• Ferrous sulphate

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Dahilia sp.
• Purple
• Silk , cotton fabrics
• Copper sulphate

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Peitophorum pterocarpum
• Yellow
• Cotton , wool
• Alum

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Aqueous extraction
Alkali or Acid extraction
Microwave and Ultrasonic assisted extraction
Fermentation
Enzymatic extraction
Solvent extraction
Super critical fluid extraction

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• Traditional method used to extract dyes from plants and other materials.
• Material is broken into small pieces or powdered and sieved.
• They are soaked in water overnight to loosen the cell structure.
• Then they are boiled at 80 to 85 degree for 1 hour to get dye solution.
• The dye solution is filtered to remove remnants.
• ADVANTAGE: Easily applied to textile material.
• DISADVANTAGE : Long time taking process , more water required , Low dye yield

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• Prepare 1% alkaline solution with 1gram Sodium carbonate or Sodium hydroxide in 100ml of
water at 100 degree .
• Experimentally it is seen that at 800 – 900C for 1 hr, the extraction is better, so this is the
optimized time & temperature for extraction process.
• Filter the dye solution.
ACID EXTRACTION
• Prepare 1% acidic solution by adding 1ml HCL in 100ml of water at 100 degree
• Experimentally it is seen that at 900 – 1000C for 1 hr, the extraction is better, so this is the
optimized time & temperature for extraction process.
• Filter the dye solution.

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• When dye containing material is treated with water or any other solvent in
presence of ultrasonic very small bubbles or cavitation are formed in liquid.
• Millions of these bubbles form and collapse every second.
• The creation of very high temperature and pressure during extraction increases
extraction , efficiency and in short time.

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• The materials are treated with minimum amount of solvent in
presence of microwave energy source.
• Microwave increase the rate of extraction process .
• So extraction can be completed in short time with better yield.

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• Eg: Acetone , petroleum ether , chloroform , ethanol , methanol
• The water or alcohol extraction method is able to extract both water soluble and
insoluble substance from plant materials.
• DISADVANTAGES:
• Toxic residues , extraction material is not readily soluble in water.
ALCOHOL METHOD:
• 50ml of alcohol is added to 50ml of soft water .
• Alcohol enters the dye material and boil.
• Filter the dye.

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• Powder is initially defatted with petroleum benzene [60-80 degree] by required
amount of ethanol by using an extractor for 72 hours.
• Extract is filtered by using filter paper and dry at 45 degree .
• Extract is kept in sterile bottle under refrigerated condition until use.
• METHANOL METHOD:
• Powder is taken and extracted by 20% aq.methanol using Soxhlet extraction
method.
• Dye powder is slightly soluble in hot water and completely soluble in alkaline
material.

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• A gas function as a super critical fluid above its critical values of
temperature and pressure.
• Their viscosity is low and can diffuse better into the substrate.
• This is non toxic and high cost.

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COLLECT THE PLANT MATERIAL WHEN THEY ARE AT PEAK OF THEIR
COLOUR

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TESTING OF RAW MATERIALS FOR ASSESSMENT OF COLOUR CONTENTS

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DRY THEM IN SHADE

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SIZE REDUCTION BY PULVERIZING

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SEPARATION OF DIFFERENT SIZE BY VIBRATING SCREEN

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EXTRACTION OF COLOURING COMPONENTS

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DRYING OF COLOURING MATTER[DYE] IN SPRAY DRYER

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PACKING : LIQUID FORM , PASTE FORM / POWDER FORM

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• High-performance liquid chromatography - (HPLC)
• Liquid Chromatography
• Liquid Chromatography-Mass Spectrometry - (LC MS)
• Spectrophotometer

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• A weaver’s garden : growing plants for natural dyes and fabrics – Rita buchanan
• Handbook on natural dyes for industrial application
• Natural dyes for textiles : sources , chemistry , and application – padma shree
vankar