Now You Know Salt Free Dyeing of Cotton Fabric with Reactive Dyes

Salt Free Dyeing of Cotton Fabric Using Reactive Dye

Yogesh.T
Dept of Textile Chemistry
SSM College of Engineering
Komarapalayam – 638 183, India
Email: yogeshdtp66@gmail.com

ABSTRACT

Cellulose fabrics dyed with reactive dyes require a large amount of salt and alkali, which affect environmental pollution and fresh watercourses. Due to the hydrolysis of the dye during dyeing, the dyeing effluent consists of large amount of hydrolyzed dye. And it requires a high volume of water to remove hydrolyzed dye in washing process. The cotton fabric is dyed with reactive dyes using conventional method. This method requires more electrolytes for exhaustion and alkali for fixation. The use of high salt concentration and low reactive dye fixation lead to environmental problem related to highly colored effluent with high salt content .these problem can be overcome by improve the dye substantively of cotton in the absence of salt and pretreating the fabric with polyacrylamide at different concentration and the primary hydroxyl groups of cellulose modified into amide groups then treatment at different concentration using pad-dry process. Pretreatment sample are dyed without salt as an electrolyte.

The pretreated sample increases the dye uptake as well as deep color yield k/s value, washing and rubbing fastness. Then main function of pretreatment to improve dye & fiber affinity and also control the toxicity of effluent .

Samples were dyed and evaluate the dye uptake, shade % and also the discharged solution is evaluated for BOD, COD& TDS value.

CHAPTER 1

INTRODUCTION

Cotton fibers are widely applied in textile industry due to its excellent properties of hygroscopicity, air permeability, biodegradability, no static electricity, good comfort and this fiber has good strength and it is known to provide comfort, good moisture absorption and good wicking properties etc. The dyeing of these fibers are generally done with reactive dyes due to its brilliancy ,variety of hue, high wet fastness, convenient usage and high applicability. These reactive dyes contain a reactive group, either a haloheterocycle or an activated double bond, that when applied to a fiber in an alkaline dye bath, forms a chemical bond with hydroxyl group on the cellulosic fiber.

The popularity of reactive dyes for dyeing of cotton, environmental problems associated with their use have received attention. Since cotton has only moderate affinity for most reactive dyes, large quantities of electrolytes such as NaCl or Na2So4 (40-100 gpl) are normally required for exhaustion. Hence dye bath exhaustion and fixation can still be as low as 50% for some dyes. Wastewater therefore contains a significant quantity of dye and salt, leading to serious environmental problems. In recent years, reactive dyes maintain the largest annual consumption in the world among the dyes used for which establishes its important status in the dye manufacture industry. But some problems, such as low dye utilization, large amount of electrolyte used and high volume of wastewater discharged, always exist in the application of reactive dyes. The dyeing of one kilogram of cotton with reactive dyes demands from 70 to 150 litre water, 0.6-0.8 Kg NaC1 and from 30 to 60 g dyestuffs. Due to these problems this class of dyes is the most unfavorable one from the ecological point of view, these effluents produced gives high values of BOD/COD (Biological oxygen demand / Chemical oxygen demand) and increases salinity of the rivers affects the delicate biochemistry of aquatic life. More than 80,000 tons of reactive dyes are produced and consumed each year, making it possible to quantify the total amount of pollution caused by their use.

It has been found that pretreatment of cotton before dyeing can offer a simple and effective method of improving dye-fibre affinity, avoiding the need for salt as an electrolyte in the dye bath. It has been found that polyacrylamide is a physical modifying agent.

In this process a new fiber modification technique based on cationic acrylic copolymer is retreated with cotton fiber because it believed that pre-treated of cellulosic fiber with Polymer to offer an opportunity for increasing both the substantivity and reactivity of fibers towards reactive dyes under neutral conditions. The nature of a reactive polymer resin is such that it may react with nucleophilic sites in cellulosic fibers or in the polymer itself, thus fixing the polymer to the substrate. During subsequent dyeing, further reactions between the polymer and the dyestuff, the fiber and the dyestuff, and the fibre and the polymer and can be expected to take place, forming cross-link within the fibers.

The pretreatment of cotton fabric with polyacrylamide demonstrates the introduction of functional amino groups which increase the substantivity and also the reactivity of cotton. The cationic charged amino groups may be involved in the adsorption of anionic chromophore of reactive dyes. The improved dye ability is postulated due to the presence of amide groups (-CONH2) available from the polyacrylamide which also tents to improve the reactivity of cellulosic substrate. The process involve in pad-dry process at 80*c. The attachment of the dye molecules onto the partially-modified cellulosic substrate is by covalent bonding since no dyes strips out from the dyed sample. The fastness values of all such dyed samples are quite satisfactory and comparable with those of conventional dyed samples.

1.1 OBJECTIVES

To elimination of salt as an electrolyte.
To reduce the hydrolysis of dye molecules.
To achieve maximum dye fixation.
To improve the highest dye up-take
To reduce low volume of water requirement during washing process
To improve fastness properties and compare different fastness.
To control low level of BOD,COD value
To control low level of TDS value
To reduce the environmental pollution.

CHAPTER 2

LITERATURE REVIEW

2.1 THEORIES OF COLOUR AND CONSTITUTION
A compound appears colored if it selectively absorbs light in the visible region and reflects the light of wave length in the rest of the visible region. The amount of light energy absorbed in the visible spectrum is the only responsible factor for the shade of the color. The main function of absorbed energy is to raise the molecule from the ground state energy to the excited state.

If the electrons of a molecule are tightly bound as in saturated compound no light of visible will be absorbed and hence the compound appears colorless. If the electrons of a molecule are loosely bound as in saturated compound absorbance occurs in the visible region and hence the compound appears colored.

Types and definition
Coloring materials are mainly of three types. Dyes, pigments and lakes (ingrain dyes). A dye has three parts in its structure chromophore, chromogen and auxochrome and is soluble in a specific medium under certain conditions.

Chromopores: Chromopores are group of atoms , the II electrons of which may get transfer from ground state to excited state by absorption of radiation ,thus producing the hue.

Auxochromopores: Auxochromopores are group of atoms which tend to increase resonance by interacting the unshared pair of electrons on nitrogen or oxygen atoms of the auxochromes, with II electrons of aromatic ring. Auxochrome is a substituted acidic or basic group in dye structure to intensify depth of shade, e.g. -OH, COOH, SO.H, -NH, -NH(CH.). etc.. Further addition of substituents to dye structure deepens the shade and extent of deepening varies with increase in molecular weight of dye.

Chromogen retains chromophore and plays a crucial role to determine the final hue and its affinity for fibre, fastness, stability, etc.

Substantivity / Affinity:
The substantivity of a dye for a fibre can be defined as an attraction between the fibre and the dye under given dyeing conditions, where by the dye is selectively extracted from the an application medium by the fibre. The term affinity is used as it is more clearly defined and can be given numerical value (usually in joules per mole). It is defined as the difference between the chemical potential of the dye in its standard state in the fibre and the corresponding potential in the dye. In simple terms substantivity or affinity indicates the ability of a dye to go from the solution phase to the fibre.

Exhaustion:
This is a measure of the proportion of the dye absorbed by the fibre relation to that remaining in the dye bath. Thus, it indicates the amount of dye that has moved from the solution into the fibre under given dyeing conditions. It is also a measure of the substantivity of the dye for the fibre.

Exhaustion is defined as the mass of dye taken up by the material divided by the total initial mass of dye in the bath, but for a bath of constant volume.

For example, if the exhaustion of a dye bath is 75%, it means that 75% of the dye in the dye bath has moved from the dye solution or dye liquor into the fiber. The term exhaustion is mainly applicable to batch –wise dyeing which is also called exhaust dyeing. Textile yarn and fabric are often dyed by the exhaust dyeing technique.

Aggregation:
Aggregation numbers - the average number of dye molecules in a micelle - had been determined from diffusion coefficients, electrical conductivity measurements, osmotic pressures, membrane filtration, and light scattering. Aggregation increases with increasing dye concentration and decreases with increasing temperature. Exact aggregation numbers and the number of incorporated counter ions, which determine the actual overall electric charge of the micelle, are imprecisely known. It is usually assumed that a rapid exchange occurs between free dye molecules in the solution and dye micelles of various sizes.

Material to Liquor Ratio:
This expression refers to the weight volume relationship between the fibre to be dyed and the total volume of dye bath .It is normally abbreviated as MLR and sometimes written as M:L ratio. An M:L ratio of 1: 10 means that a dye bath volume of 10 litres is required to dye 1kg of dry fibre.

The material to liquor ratio is also referred to as an inverse ratio and called the liquor to goods ratio or simply the liquor ratio and this ratio is given by the following expression.

Total volume of dye liquor in ml
Liquor to goods ratio = -----------------------------------------------------------------------
Dry weight of material dyed in grams.

Thus 5 gms of material dyed at a liquor to goods ratio of 5:1 would use 5x5 =25ml of dye liquor. Alternatively, 3gms of material dyed in dye bath of 60ml has a liquor / goods ratio of 60/3 or 20 / 1 or 20:1

Shade Percentage:
Shade percentage refers to the quantity of dye taken for a dyeing expressed as a percentage of the dry weight of the fibre to be dyed. For example, If 1g of a dye is taken fordyeing100gof textile material, the shade percentage is referred to as 1 % Shade. If a kilogram of fibre is required to be dyed to a3.5 5shade, the amount of dye to be taken would be (1000x 3.5 ) /100 = 35 grams.

Formula for calculation
Ml of dye solution required or added = Percentage of depth of shade x weight of fibre to be dyed in gms.

Concentration of stock dye solution in g/100ml

For example. If 3% shade is required to be dyed on 4gof cotton yarn using a solution of one gram of dye in200ml of water (ie 0.5g in 100ml water ), the ml of the stock dye solution required would be, ml of dye solution required or added = 3x4 / 0.5 =24ml

2.2 THE GENERAL THEORY OF DYEING
Dyeing is the process of coloring textile materials by immersing them in an aqueous solution of dye, called dye liquor. Normally the dye liquor consists of dye, water and an auxiliary. To improve the effectiveness of dyeing, heat is usually applied to the dye liquor.

The general theory of dyeing explains the interaction between dye, fibre, water and dye auxiliary. More specifically, it explains:

Force of repulsion which are developed between the dye molecules and water.
Force of attraction which are developed between the dye molecules and fibres.

These forces are responsible for the dye molecules leaving the aqueous dye liquor entering and attaching themselves to the polymers of the fibres.

The dye molecule
Dye molecules are organic molecules, which can be classified as:

Anionic – in which the colour is caused by the anionic part of the dye molecule;
Cationic – in which the color is caused by the cationic part of the dye molecule;
Disperse- in which the colour is caused by the whole molecule. The first two dye molecule types are applied from an aqueous solution. The third is applied from an aqueous dispersion.

A dye stuff is a substance which is capable of colouring a textile material in such a manner that it associate closely with the fiber , that it is not removable by simple physical means (eg : rubbing or mild deterging ). It must be soluble in water, are capable of going into solution by chemical means, whereby a highly dispersed condition may be regarded as a form of solution.

An essential feature of the dyeing process is that the dye molecule must be capable of entering the fibre structure, the path for the dye molecules is provided by the intermolecular spaces in the fibre and once the dye has entered the fibre structure it becomes firmly attached to the surface of the molecules either by purely physical forces (Secondary Valences) or by chemical combination. The former mode of attachment is believed to be prevalent in the dyeing of cellulosic fibres, the latter mode in the dyeing of protein fibres. Acetate rayon and synthetic fibres resist penetration by the dye molecules, but certain dyes are capable of forming a solid solution with the fibrous molecule; for dyeing with other dyes, the synthetic fibres may be swollen with suitable agents. Swelling of the fibers appears to play a large part in dyeing of all fibres, and is principally affected by water (or solvents in the case of synthetics) and by raising the temperature of the dye bath.

The dyeing process can thus be considered as taking place in three phases:

Attachment of the dye molecule to the surface of the fibre
Penetration into the intermolecular spaces as well as diffusion through the fibre,
Orientation (and fixation) along the long chain molecules.

Dyeing is governed by three factors, the dye, the fibre and the dye liquor. All the three lead an independent assistance which influences the technique of dyeing. A dye must be water soluble in order to dye textile materials. It may be soluble by nature of its chemical interference. The solution of the dye from which it is applied is called the ‘dye bath’. A dye may have direct ‘affinity’ for a fibre (or vice versa) i.e., it is held by the fibre either physically (adsorption) or chemically (combination) as soon as the fibre is immersed in the dye bath .Accumulation of the dye in the fibre is a gradual processes, the rate of such building up being referred to as the ‘rate of dyeing’. This rate of dyeing is governed by the condition of the dye bath , namely concentration of dye, temperature , and presence of electrolytes;. It is proportional to all three factors. The rate of dyeing I is also influenced by the ‘ Material to liquor’ which is expressed by a fraction, e.g. 1:20, which means one part (by weight) of the textile material dyed in twenty times its weight of dye bath. The rate off dyeing decreases with increasing ratio of goods to liquor.

Dyeing is carried out to produce a certain ‘Shade’ by which is meant a certain colour, difference in shade being due to different ‘Hue’. A blue shade may, for instance have a greenish or a reddish hue. The amount of dye needed for the production of a certain depth of shade is expressed as a percentage of the weight of the material. A 1 % dyeing represents a shade produced by the colouring of 100 lbs. of material with one lb. of (commercial) dye, under well defined dyeing conditions. It is necessary to define these conditions because of their influence on the ‘exhaustion’ of the dye bath.

2.3 FASTNESS PROPERTIES OF DYES:
When a dye is present on a fabric it is expected to have certain properties. Thus when a dyed or printed fabric (garments, curtain materials, furnishing fabric etc.) is exposed to sun light during its use, the dye should not fade or change its colour, i.e., it should have high light fastness.

The dye should posse’s good washing fastness if the cloth dyed with it is used for making garments. Otherwise staining of garments which strip dyestuffs occurs during the washing of many garments. These dyes should also have good perspiration fastness. Perspiration of certain people is acidic in nature and of theirs, alkaline. When people wearing colored garments perspire a part of the dye coming into contact with the perspiration may be strip and stain the undergarment or the skin of the wearer.

A single dye, which dyes all the known major textile fibres is not made yet. Some of fibres are dyed with certain classes of dyes and other fibres with other classes. Thus cotton, mercerized cotton, linen, viscose rayon, cupramonium rayon etc. (cellulosic fibers) are dyed with vat, reactive, direct, azoic (naphthol and base), sulphur, oxidation colour, mineral colour and basic dye (after moderating). Wool and silk (protein fibres) are dyed with acid dyes, basic dyes (without the use of mordant), acid mordant dyes (special acid dyes which can combine with metals like chromium dyeing and produce wash fast dyeing .Example metal-complex dyes (dyes containing the metal atom in their molecular structure so that the metal atom need not be incorporated into the dye during dyeing) .

Acetate and triacetate and polyester fibres are dyed with disperse dyes. Polyamide fibres are dyed with acid dyes, metal-complex dyes, disperse dyes. Acrylic fibres are dyed with basic (cationic) dyes.

Dye selection
There are numerous factors involved in the selection of dyes for colouring a fabric in a particular shade. Some of these are:

The types of fibres present
The form of the textile material and the degree of levelness required - level dyeing is less critical for loose fibres, whichare subsequently blended, than it is for fabric
The fastness properties required for any subsequent manufacturing processes and for the particular end-use
The dyeing method to be used, the overall cost, and the machinery available
The actual colour requested by the customer.

2.4 REACTIVE DYES
In 1956 Rattee + Stephen (ICI) introduced “first” reactive dyes– chlorotriazines.

Reactive dyes are chemically react with cotton fibre and form covalent bond and become a part of the fibre. The reactive dyes contains several groups that are shown in below,

water solubilising group
chromophore
bridging group
reactive group
leaving group

2.4.1 Properties of Reactive Dyes:

It have sulphonic acid groups in the molecules and readily soluble in water.
Less substantive than direct dyes, hence more salt is required for exhaustion.
Dyestuff react and combine chemically (covalently) with cellulose, so called reactive dyes.
Easy penetration and good leveling property.
Moderate to good light and wash fastness properties.
Formation of covalent bond occur in alkaline medium
These dyes, unlike any other class of dye stuffs, react and combine chemically (covalently) with cellulose and this leading to excellent wash-fastness.
These dyes give very bright shades such as orange, pink, magenta etc, which were not possible with other class of dyes.
They do not react with water nearly as readily as with cellulosic hydroxyl in alkaline conditions, so that they can be applied from an aqueous solution.
Reactivity of the dyestuffs can be reduced when desirable by blocking one of the reactive chlorine atoms giving H-type Procions.
Procions are dyes with small molecules; their molecules do not have to be very long as those of direct dyes to match the distance between absorption sites on the fibre. Short molecules bring two advantages (a) Clarity and brightness of hue and (b) easy penetration and therefore good leveling.
Because there is some, even although not very much reaction between procion dyestuffs and water, it is very important to wash the dyed fibre thoroughly clean and free from the reaction product with water.
The formation of the covalent bond between dye and fibre occurs under alkaline conditions. The presence of acids may reverse this process. Perspiration and atmospheric pollution which are both slightly acid may affect textile materials coloured with reactive dyes and result in some fading
Reactive syes can be applied to cellulosic fibres by exhaust (batch), pad batch (sermi-continuous), continuous dyeing method.

2.4.2 Classification of Reactive dyes:
Reactive dyes can be classified basically into three groups

Group 1: Alkali Controllable
Group 2: Salt Controllable
Group 3: Temperature Controllable

On the basis of reactive system, reactive dyes can be classified as

Monofunctional Reactive dyes:

Dyes are characterized by the presence of reactive groups- one or more reactive species at individual locations in the dye molecule.
Examples of this type is mono chloro triazine, dichloro triazine and vinylsulphone dyes

Bi Functional Reactive dyes:
These dyes are characterized by the presence of two reactive groups of same type ( MCT or DCT) or different type(MCT&VS) at two different locations in the dye molecule.

Bifunctional again divided into:

1. Homo bifunctional- dyes having two reactive systems of same type (triazine or vinylsulphone).
2. Hetero bifunctional – dyes having two reactive systems of mixed type (triazine - vinylsulphone).

These dyes have High exhaustion and high fixation with good colour yield.
Less pollution
Very popular for exhaust dyeing applications
High exhaustion – due to high molecular weight of dyes
High fixation – due to presence of two reactive systems

2.4.3 Classification based on Reactive system:
Reactive dyes form a covalent bond between fibre and dye. They are classified depending on the reactive group present and the optimized conditions in which they are best used. Depending on the type of reaction, the reactive dyes are broadly divided in to two categories:

A. Dyes reacting through Nucleophilic substitution reactions
B. Dyes reacting through Nucleophilic addition reactions.

A. Dyes reacting through Nucleophilic substitution reactions:

(1) Dichlorotriazynilamino types of dyes

Salt Free Dyeing of Cotton Fabric Using Reactive Dye Now You Know Salt Free Dyeing of Cotton Fabric with Reactive Dyes

Figure.2.1: Structure of Dichlorotriazynilamino dyes

These are more reactive than monochloro type of dyes and require lower temperature and milder alkali for dyeing and fixation. These are known as Cold brand reactive dyes.

(2) Monochlorotriazynylamino type of dyes

Figure 2.2: Structure of Monochlorotriazynylamino dyes

These require higher temperature and stronger alkali for dyeing and fixation. These are called hot brand reactive dyes.

B. Dyes reacting through Nucleophilic addition reactions:

(1) Dyes containing Vinyl sulphone group
As such this is not soluble in water, so it is marketed in its soluble form i.e., β - hydroxy ethylene sulphone sulphuric acid ester derivatives.

RSO₂–CH₂-CH₂OSO₃Na

2.4.4 Chemistry behind Reactive Dyeing:
The dyeing principle is based on fiber reactivity and involves the reaction of a functional group of the dyestuff with a site on the fiber to form a covalent link between the dye molecule and the substance.

The Four structural feature of typical reactive dyes molecule are:

The chromophoric grouping, contributing the color
The reactive system, enabling the dye to react with hydroxy group in cellulose.
A bridging group that links the reactive system to the chromophore.
One or more solublising group, usually sulphuric acid substituent attached to the chromophoric group for their colour, although the azo chromophore –N=N- is by itself the most important.

All the reactive dyes contain sodium sulphonate group for solubility and dissolve in water to give coloured sulphonate anions and sodium cations. Most reactive dyes have one to four of these sulphonate group, General form of reactive dye is as follows:

S------R----B----X

Where,

S = Water solubility group
R = Chromophore
X = Reactive System
B = Bond between reactive system and Chromophore

2.5 COLD BRAND AND HOT BRAND REACTIVE DYES
The reactivity of these dyes is dyes are due to the chlorine atoms attached to the triazine ring. When two chlorine atoms are present in the dye molecule are called Dichloro Procions. Dichloro procions are referred to as M-type procions and their characteristic is that they will combine with alkaline cellulose at room temperature (20oC to 30oC) and hence they are called cold brand reactive dyes when only one chlorine atom is present in the dyestuff molecule, the reactivity of the dye decreases considerably and the dyeing has to be carried out at a higher temperature (65oC to 80oC). Hence these dyes are called hot brand reactive dyes. Mono chloro procions are referred to as ‘H’ type procions. Normally ‘M’ Brands are suitable for dyeing and H brands are suitable for printing.The instability of the solutions of the cold-dyeing procion colours was a serious disadvantage in their application to textile printing. The stock solution for printing must be kept and used for several hours. The reactive dyes having only one chlorine atom in their molecule are less reactive. Their aqueous solutions, therefore, are more stable and very suitable for printing.

2.5.1 TYPES OF REACTIVE DYES:

Cold brand reactive dye -‘M’ brand
Hot brand reactive dye -‘H’ brand (or ‘X’ brand)
High exhaust reactive dye -‘HE’ brand
High exhaust reactive dye -‘ME’ brand
Vinyl Sulphone reactive dye - for dyeing and printing
Low salt reactive dye - LS dyes

2.6 APPLICATION OF HOT BRAND DYES ON COTTON:

MONOCHLOROTRIAZINYL, REACTIVE DYES (OR) PROCION + H BRAND

The mono chlorotriazinyl dyes or hot brand reactive dyes are less reactive. Their aqueous solutions are more stable but they do not react with cellulose so readily and the temperature of dyeing must be increased to 60oC to 70oC and in some cases, as high as 90oC to 95oC.

The dyestuffs are dissolved by making them into a paste with cold water, followed by dilution with more water.

Figure 2.3: Cibacron Brilliant Red B

The dye bath in made by dissolving sufficient common salt to give a concentration of 40 to 80 parts per 1000 according to the depth of the shade, the goods already having been entered. The temperature is brought up to 40oC and the machine is run for five to ten minutes in order that the fabric can be uniformly impregnated. The pre dissolved dye is then added in two portions at five minute intervals followed by the alkali which should be 20 parts per 1000 of soda ash. The alkali should be added in two portions at five minute intervals and the temperature then raised to between 60 to 90oC according to that which is recommended for the dye selected. Dyeing is continued for a period of 20 to 40 minutes and then continued for 30 to 60 minutes when soda ash (Alkali) is used. After dyeing, the materials must be rinsed and soap boiled to remove hydrolysed and unfixed dye.

After treatment:

Treat the dyed material with 1 to 2 g/l of neutral soap at boil for 15 minutes and wash it.
Treat the soaped material with 2 to 3 g/l of cationic dye fixing agent at 40oC for 20 to 30 minutes and dry it.

2.7 ON GOING RESEARCH ON SALTFREE DYEING OF COTTON FABRIC USING REACTIVE DYES
Cellulosic fabric is dyed with reactive dyes require large amount of salt, which pollutes fresh water . Due to the hydrolysis of the dye, the dyeing effluent consists of large amount of hydrolyzed dye, and it requires high volume of water to remove the hydrolyzed dye in washing process. The cotton fabrics were dyed with reactive dyes using conventional method and pre-treating the fabric with Polyvinylamine Chloride. Pretreated samples were dyed without using salt as an electrolyte. It was found that pretreatment of cotton fabrics with Polyvinylamine Chloride increases the dye uptake and shows good wash fastness and rubbing fastness. There was a slight increase in crease recovery angle and flexural rigidity in pretreated sample. It is considered that Polyvinylamine Chloride is found to be effective for pretreatment in salt free dyeing of cotton fabrics.

It has been found that pretreatment of cotton before dyeing can offer a simple and effective method of improving dye-fibre affinity, avoiding the need for salt as electrolyte in dye bath. It has been found that Poly (Vinylamine Chloride) [PVAmHCl] is a physical modifying agent. Its wide range of properties has found use in Catalysis, Chelating, liquid chromatography, treatment of wastewater, recovery of oil and in polymeric dyes.it involving chemical modification of Cellulosic. Nonreactive pretreatments including some polymers with affinity for cellulose tend to be desorbed during dyeing and inhibit uptake of dye or cause it to precipitate. This study has established the value of polymeric quaternary ammonium compounds, amines or amides, which may be attached to cotton by non-chemical mechanisms. Despite the encouraging results obtained with non-reactive polymers in the salt free dyeing of cotton, problems remain in dye selection and obtaining level results. The aim of this work to determine the effectiveness of PVAmHCl as pretreatment agent of cotton fabrics in improving its dyeability with reactive dyes and in achieving evenness of dye uptake. It was also to determine the effectiveness of pretreatment of dyed fabrics on K/S value and fastness properties like wash fastness and Rub fastness. Various physical properties like tensile strength, flexural rigidity,cloth crease recovery angle and aerial density were also determined to see the effect of PVAmHCl. Results obtained were analyzed to arrive at some advantages of the pretreatment.

2.7.1 FUNCTION OF POLYVINYLAMINE CHLORIDE (PVAmHCl)
PVAmHCl has been used as a physical modifying agent. Due to its wide range of properties, PVAmHCl has found use in catalysis,liquid chromography, treatment of wastewater, recovery of oil and in polymeric dyes. It has been used in application as diverse as paper making and biomedical research, but it’s used for modification of cotton for salt free dyeing as not been previously reported. Interest in PVAmHCl arises from the presence of large number of cationic sites (NH+3Cl-). Nucleophilic sites involving primary amino group within the PVAmHCl molecule are of particular value for achieving salt free dyeing of cotton with reactive dyes. As the pH increases, the proportion of NH+3Cl- groups in the molecule decreases and that of NH2 groups increases.

Process
The fabric sample was desized by using acid desizing method. The fabric was scoured by alkali method using standard procedure. Then it was subjected to bleaching process using hydrogen peroxide as bleaching agent. Padding method was used for pretreatment of cotton with PVAmHCl the pH of pretreatment liquor was maintained at buffer comprising potassium dihydrogen phosphate and Sodium Hydroxide. Padding was carried out using 2 dips (4 min for each) and 2 nips. Fabric samples were pre dried at room temperature and then baked at 102oC for 12 min in rapid baker. Padding was done at different concentration of PVAmHCl.Then cotton fabric dyed with salt and without salt, then process efficiency analysed and compared.

2.8 SALT FREE DYEING WHY?
In recent years there has been an increasing awareness about environmental friendliness in all human activities. The textile industry is a water intensive industry with water being used in every stage of wet processing from sizing, desizing, scouring and bleaching of fibers to the dyeing, finishing and printing of fabrics. Every textile plant requires large volumes of water and produces high volumes of effluent wastewater. The typical textile dye wastewater composition is quite complex. The demand for environmental friendly dyes and application processes is therefore very strong.

Reactive dyes have become very popular for cotton due to its brilliancy, variety of hue, high wet fastness, convenient usage and high applicability

Reactive dyes are anionic in character and cotton fibers also adopt anionic surface charge in water causing limited exhaustion of dye due to charge repulsion. Large quantities of electrolyte (30-100 g/l) are thus added to overcome this problem. One of the major problem of reactive dyeing is the large amount of electrolyte required for exhaust and pad application [4] which leads to environmental problem. In addition, inadequate dye exhaustion and fixation result in coloured effluents. As environmental problems arising from dyeing with reactive dyes have become critical, many studies have been devoted to improving the substantivity of cotton fiber for reactive dyes, thus reducing or eliminating the amount of electrolyte used.

2.9 FUNCTION OF SALT IN THE DYEING PROCESS:
The salt in the reactive dyeing increases the affinity of the dye towards the Cellulosic substrate. Salt increases the exhaustion rate of reactive dyestuffs.

As reactive dyestuffs have a lower affinity, more inorganic salt is required when using reactive dyestuffs in order to accelerate absorption. While the amount of inorganic salt used varies according to the type of dyestuff used, recently developed high-fixation dyestuffs with improved affinity allow the amount of inorganic salt to be reduced.

Due to considerations of effectiveness and cost, both Glauber's salt and common salt (sodium chloride) are used in dyeing. In terms of their role as an inorganic salt, these two are effectively the same because of the sodium cation active in both.

2.10 ROLE OF SALT IN REACTIVE DYEING:
Inorganic salts have two main functions in exhaustion dyeing with reactive dyestuffs:

Improving the affinity of the dyestuff
Acceleration of the dyestuff's association and lowering of its solubility.

Generally reactive dyes contains sulphonic acid (-SO3H) group which is insoluble in water. During the manufacturing of the reactive dyes these sulphonic acid groups are converted into the sodium salt of sulphonic acid (-SO3Na) which is soluble in water.

Reactive dye – SO3H + Na⁺ → Reactive dye SO3Na

Figure.2.4: Salt reaction

Generally when the reactive dye goes in the water, it is solublised giving dye anions and sodium cations

Reactive dye – SO3Na + Water -- → Reactive dye – SO3⁻ + Na ⁺

(Dye anion) (Sodium cation)

2.11 WHY SALT IS USED IN DYEING?
The textile substrate and dye molecule, not necessarily should have of homogeneous characteristics to combine with each other. In such case, we require some catalyst to facilitate dyeing action on fabric. Salt plays this crucial role of catalyst. Salt has an extremely high affinity for water. Broadly speaking, Salt is necessary in three ways, firstly, to drive dye into textile during the dyeing process in textile. Secondly, use of salt leads to maximum exhaustion of dye molecules during dyeing process in textiles. Thirdly it is used as an electrolyte for migration, adsorption and fixation of the dyestuff to the cellulose material.

Salts plays important role in reactive dyeing by improving the affinity of the dyestuff towards the fibre and acceleration of the dyestuff's association and lowering its solubility. Normally, Glauber's salt or common salt/ vacuum salt is used for this purpose. The presence of chlorine ion in the common salt may cause corrosion of the equipment. Hence, Glauber's salt is always preferred over common salt. Glauber's salt is a common name for sodium sulfate decahydrate, Na2SO4.10H2O; it occurs as white or colorless monoclinic crystals. Upon exposure to fairly dry air it effloresces, forming powdery anhydrous sodium sulfate. Johann Glauber’s was the first to produce the salt (from Hungarian spring waters). Glauber's salt is water soluble, has a salty, bitter taste, and is sometimes used in medicine as a mild laxative; it is also widely used in dyeing. Vacuum salt is the common name of sodium chloride (NaCl).

2.12 STANDARDS NORMS FOR DISCHARGE OF EFFLUENTS WATER

S. No.	Industry	Parameter		Standard (applicable for all modes of disposal*)
1	All Integrated textile units, units of Cotton / Woollen / Carpets / Polyester, Units having Printing / Dyeing / Bleaching process or manufacturing and Garment units.	TREATED E	EFFLUENTS	Maximum concentration values in mg/l except for pH, colour, and SAR
		pH		6.5 to 8.5
		Suspended Solids		100
		Colour, P.C.U Cobalt Units)	(Platinum	150
		Bio-Chemical Demand [3days (BOD₃)	Oxygen at 27^oC]	30
		Oil and Grease		10
		Chemical Oxygen Demand (COD)		250
		Total Chromium as (Cr)		2.0
		Sulphide (as S)		2.0
		Phenolic Compounds (as C₆H₅OH)		1.0
		Total Dissolved Solids, Inorganic (TDS)		2100**
		Sodium Absorption Ratio (SAR)		26**
		Ammonical Nitrogen (as N)		50

Table 2.5 .Standared forms for effluent water

NOTE:

*In case of direct disposal into rivers and lakes, the Central Pollution Control Board (CPCB) or State Pollution Control Boards / Pollution Control Committees (SPCBs / PCCs) may specify more stringent standards depending upon the quality of the recipient system.
**Standards for TDS and SAR shall not be applicable in case of marine disposal through proper marine outfall.
The treated effluent shall be allowed to be discharged in the ambient environment only after exhausting options for reuse in industrial process / irrigation in order to minimise freshwater usage.
Any textile unit attached with the Common Effluent Treatment Plant (CETP) shall achieve the inlet and treated effluent quality standards as specified in serial number 55 of Schedule-I to the Environment (Protection) Rules, 1986 and shall also be jointly and severally responsible for ensuring compliance.
The standalone Micro, Small and Medium Enterprises (MSMEs) as per the MSME Development Act, 2006 shall meet the values specified above.

CHAPTER 3
METHODOLOGY

3.1 RAW MATERIAL:

FABRIC:
100% cotton grey plain woven fabric was used for this project, which is having Arial density of 102 g/m2 and it has been obtained from vetrivel textiles, erode, India and the fabric characteristics are listed in the Table.

Geometrical parameters of fabric:

Fabric	Ends/inch	Picks/inch	Gsm	Warp count(Ne)	Weft count(Ne)	Thickness(mm)
100% cotton	106	96	102	100	80	0.14

Table .3.1 fabric parameters

3.2 DESIZING OF COTTON FABRIC
Desizing is the process of to remove size or starch from the Grey fabric which is applied during weaving and to make the fabric more absorbent to facilitate dyeing and printing.

3.2.1 Recipe:

Enzyme - 2.0%
Wetting agent - 1.0%
Sodium chloride - 1.0%
Temperature - 50-60°c
PH -6 - 7
Duration -1-2 Hours

3.2.2 Procedure:

The given sample is weighed by using electronic balance
↓
Prepare the desizing bath set with 2.0% enzyme,1.0% wetting agent and salt by using 1:20 material to liquor ratio.
↓
The temperature of the bath is to be raised to 50°c then enter the well wetted and squeezed material into the bath and worked for 2 hours
↓
Then the material is taken out from the bath and washed thoroughly using hot water and cold water
↓
Finally the material is squeezed and dried.

3.3 SCOURING OF COTTON FABRIC
Scouring is the process of to remove natural impurities as well as added impurities.the impurities such as oils, fats, wax and colouring matters.the hydrophobic in character as possible and leave the fabric in a highly absorptive condition without under going chemical or physical damage of the material.

3.3.1 Recipe:

Wetting agent - 1.0%
Sodium hydroxide (NAOH) - 2-3%
Sodium carbonate(NA2SO3) -1.0%
Soap - 0.5%
Temperature -boiling temperature
PH - 10 to 11
Duration - 2 to 3 hours

3.3.2 Procedure:

The given sample is weighed by using electronic balance
↓
The scouring bath is set with caustic soda 2-3%,soda ash 1%,wettind agent 1% and soap 0.5% by using material to liquor ratio as 1:20
↓
The temperature of the bath is raised boil and scouring solution is stirred
↓
The well wetted and squeezed material is entered into the scoring bath and is worked for 2 to 3 hours
↓
The material is turned out frequent intervals for proper scouring
↓
The material is completely immersed under boiling liquor.the material should not be exposed to atmospheric air.
↓
After scouring treatment, material is taken out from the bath wash thoroughly then the sample is neutralized with 1% HCL
↓
Then wash thoroughly and dried .thus scoured sample.

3.4 BLEACHING OF COTTON
Bleaching is the process of to remove the natural colouring matter and any other colouring matter is removed from cotton.then improve the whiteness of the material and absorbence also improved by bleaching process. During scouring of cotton all impurities are removed except the natural colouring matter leaving material satisfactorily absorbent.

3.4.1 Recipe:

Wetting agent - 1%
Hydrogen peroxide - 2-8%
Soda ash - 0.5 -1%
Caustic soda - 0.5 %
Sodium silicate - 1 to 2%
Temperature - 80-85°c
PH - 10 to 11.5
Duration - 1-2 hours

3.4.2 Procedure:

The given sample is weighed by using electronic balance
↓
Prepare the bleaching bath with the required amount of wetting agent,hydrogen peroxide,sodium silicate,soda ash,caustic soda using 1:20 material to liquor ratio
↓
The bleaching bath is well stirred
↓
Adjust the PH of the bath 10.5 to 11.0 by adding sodium carbonate
↓
Then raise the temperature to 50°c.enter the well scoured fabric into this bath,work for 10 mins
↓
Then raise the temperature to 85°c and continue the bleaching bath for 2 hours
↓
Finally remove the fabric wash well and dried.

3.4.3 After treatment:

After bleaching of cotton with hydrogen peroxide is over, a residue Of hydrogen peroxide may left out in the fabric
↓
Take 1-3% catalase enzyme and treat the material for a period of 15 mins at room temperature with neutral PH.
↓
Then cold wash neutralizing with 0.5% acetic acid
↓
Finally thoroughly wash and dry.

3.5 CONVENTIONAL METHOD OF DYEING USING SALT

3.5.1 Recipe for dyeing process:

Dyes	Shade %	Wetting agent %	Salt in gpl	Soda ash in gpl	Levelling agent	Temp °c	Time
Red HE3B(120)	1 %	1-2 %	20 gpl	10 gpl	1-2 gpl	80-85°c	1 – 2 hours
	2 %	1-2 %	30 gpl	20 gpl	1-2 gpl
	3 %	1-2 %	40 gpl	30 gpl	1-2 gpl
Red HE8B(1520	1 %	1-2 %	20 gpl	10 gpl	1-2 gpl	80-85°c	1 – 2 hours
	2 %	1-2 %	30 gpl	20 gpl	1-2 gpl
	3 %	1-2 %	40 gpl	30 gpl	1-2 gpl
Yellow HE4R(81)	1 %	1-2 %	20 gpl	10 gpl	1-2 gpl	80-85°c	1 – 2 hours
	2 %	1-2 %	30 gpl	20 gpl	1-2 gpl
	3 %	1-2 %	40 gpl	30 gpl	1-2 gpl
Navy blue HEGN(198)	1 %	1-2 %	20 gpl	10 gpl	1-2 gpl	80-85°c	1 – 2 hours
	2 %	1-2 %	30 gpl	20 gpl	1-2 gpl
	3 %	1-2 %	40 gpl	30 gpl	1-2 gpl
Blue HERD(160)	1 %	1-2 %	20 gpl	10 gpl	1-2 gpl	80-85°c	1 – 2 hours
	2 %	1-2 %	30 gpl	20 gpl	1-2 gpl
	3 %	1-2 %	40 gpl	30 gpl	1-2 gpl

Table 3.2 conventional dyeing recipe

3.5.2 Calculation:

Material to liquor ratio = 1:20 = fabric weight in gm × 20 (liquor ratio)

                                                   Shade % × weight of the fabric in gm
Amount of dye solution(ml) = --------------------------------------------------------------------
                                                                  Stock solution %

                                      Required amount (g/l) ×liquor ratio ×sample weight
Amount of salt (gm) = -------------------------------------------------------------------------------
                                                                           1000

                                                          Required amount(g/l) × liquor ratio × sample wt.
Amount of chemical solution(ml) = -----------------------------------------------------------------------
                                                                          1000 × conc.of stock solution %

Water = 5 × 20 = 100 ml
Required quantity of dye solution =(1% × 5 ) / (1%) =5 ml
Required quantity of salt =(20 gpl ×20 ×5) / (1000) = 2gm
Required quantity of soda ash =(30 gpl ×20 ×5) / (1000) =3 gm
Required quantity of levelling agent = (1gpl ×20×5) / (1000) = 0.1 gm
Required quantity of wetting agent =(1 ×5) / (1) =5 ml
Required quantity of water =Total amount of water(M:L:R) -dyes = 100-10 =90 ml

3.5.3 Procedure:

The required quantity of dyestuff is pasted with little quantity of cold water
↓
then dilution of hot water having the temperature of about 80°c with stirring and filteration if necessary.
↓
Prepare the dye bath with the required quantity of dyestuff in 1:20 M:L:R at 40°c .enter the well scoured/bleached wetted cotton material into the hot dye bath and work the material for 15 mins.
↓
Then temperature of the bath is gradually raised to 70-80°c.after 15 mins add the required quantity of pre-dissolved common salt preferably in 3 or 4 portions over a period of 30-45 mins.
↓
then add the required quantity of soda ash into the dye bath for fixation of the dyestuff in the fibre and work further abourt 30 mins during the addition of soda ash the dye bath temperature should not be below 80°c.
↓
Then remove the fabric from the dye bath and washed,rinsed well.

3.5.4 Soaping:

In order to remove the loosely adhered dye particles and to improve the fastness property of dyeing the material .
↓
soaping treatment with 1-5 gpl of soap at boiling condition for 30 mins .then wash ,rinse well and dry for shade.

3.6 TREATMENT OF FABRIC WITH POLYACRYLAMIDE

3.6.1 Preparation of polyacrylamide gel:

Crustacean shells
↓
Size reduction
↓
Protein separation
↓
NAOH washing
↓
Demineralization of HCL
↓
Washing and watering
↓
Discoloration
↓
Chitin
↓
Deacetylation(NAOH)
↓
Washing and watering
↓
Polyacrylamide

3.6.2 Properties of polyacrylamide:

Linear polyamine
Reactive Amino Groups
Reactive Hydroxyl Groups are available
Water soluble and positively charge at acidic PH.
Solution properties of chitosan in free Amine (-NH2) form soluble in acidic solution.
Insoluble at pH’s > 6.5 Insoluble in H2SO4
Limited solubility in H3PO4
Insoluble in many organic solvents
Soluble at pH < 6.5
Form viscous solutions
Solution shear thinning, forms gels with polyanions
Will remain soluble in some alcohol-water mixture.

3.6.3 Chemical properties of polyacrylamide:

Chitosan is a linear polyamine (poly-o-glucosamine) with reactive hydroxyl and amine group. Biocompatility, Cicatrizing,Anti-cholesterolemic agent,Chelation agent,
Biodegradable, Strengthening the immunity, Antimicrobial activity, Deodrant properties of Chitosan, Water Treatment and Pollution Control.

3.6.4 Preparation of fabric
The fabric sample was desized using the acid desizing method. The fabric was scoured by the alkali method using a standard procedure. Then, it was subjected to a bleaching process using hydrogen peroxide as the bleaching agent.

3.6.5 Pretreatment of cotton with polyacrylamide
The grey cotton fabric are treated Pre-washed cotton fabrics were immersed for 15 to 20 minutes in the polyacrylamide gel with different concentrations separately: 5%, 10%, 15%. The padding processes were then completed with pick up weight of around 80%. Finally, the cotton fabrics were dried at 80 °C for 3 min and cured at 150 °C for 3 min and finally rinsed with warm water (40 ºC) for 1 min. Finally fabric rinsed with running cold water and dried again.

3.6.6 Recipe:

Sl.no	Polyacrylamide concentration (%)	Wetting agent (%)
1	5 %	1-2 %
2	10 %	1-2 %
3	15 %	1-2 %

3.6.7 Calculation:

Material to liquor ratio = 1:20 = fabric weight in gm × 20 (liquor ratio)
= 5 × 20 =100 ml

Amoint of polyacrylamide solution(ml) = (Req. % × wt. of the fabric in gm)/(stock sol.%)
= ( 5 × 5 ) / (1%) = 25 ml

Amount of wetting agent = (Req.gpl×liquor ratio×wt.of sample)/(1000)
= (1×20×5 )/(1000) =0.1 ml

Required quantity of water =Total amount of water(M:L:R) -auxiliars
= 100- 27 =75 ml

3.6.8 Procedure:

The polyacrylamide solution are prepared at different concentration like 5%,10%,10%

↓

The bleached cotton fabric are immersed in polyacrylamide solution at neutral condition for15-20mins

↓

The fabric are squeezed by 2 bowls or 3 bowls padding mangle

↓

Then fabric are dried at 80°c for 3 mins

↓

The dried fabric are cured at 130-150°C for 3 mins

↓

The cured fabric rinsed with warm water (40°c) for 1mins

↓

The fabric are rinsed with cold water

↓

Finally dried.

3.6.9 REACTION OF POLYACRYLAMIDE THROUGH CELLULOSE:

Figure 3.4: Structure of polyacrylamide

In this process a new fiber modification technique based on cationic acrylic copolymer is retreated with cotton fiber because it believed that pre-treated of cellulosic fiber with Polymer to offer an opportunity for increasing both the substantivity and reactivity of fibers towards reactive dyes under neutral conditions. The nature of a reactive polymer resin is such that it may react with nucleophilic sites in cellulosic fibers or in the polymer itself, thus fixing the polymer to the substrate. During subsequent dyeing, further reactions between the polymer and the dyestuff, the fiber and the dyestuff, and the fibre and the polymer and can be expected to take place, forming cross-link within the fibers.

Then pretreated fabric are dryed at 80°c suitable temperature and cured at 130°c then the fabric are dyed with reactive dyes without salt .this process to eliminate the electrolyte to the dyeing process.

3.7 UNCONVENTIONAL DYEING PROCESS WITHOUT SALT

3.7.1Recipe for dyeing process:

Dyes	Shade %	Wetting agent %	Soda ash in gpl	Levelling agent	Temp °c	Time
Red HE3B(120)	1 %	1-2 %	10 gpl	1-2 gpl	80-85°c	1-2 hour
	2 %	1-2 %	20 gpl	1-2 gpl
	3 %	1-2 %	30 gpl	1-2 gpl
Red HE8B(152)	1 %	1-2 %	10 gpl	1-2 gpl	80-85°c	1-2 hour
	2 %	1-2 %	20 gpl	1-2 gpl
	3 %	1-2 %	30 gpl	1-2 gpl
Yellow HE4R(81)	1 %	1-2 %	10 gpl	1-2 gpl	80-85°c	1-2 hour
	2 %	1-2 %	20 gpl	1-2 gpl
	3 %	1-2 %	30 gpl	1-2 gpl
Navy blue HEGN(198)	1 %	1-2 %	10 gpl	1-2 gpl	80-85°c	1-2 hour
	2 %	1-2 %	20 gpl	1-2 gpl
	3 %	1-2 %	30 gpl	1-2 gpl
Blue HERD(160)	1 %	1-2 %	10 gpl	1-2 gpl	80-85°c	1-2 hour
	2 %	1-2 %	20 gpl	1-2 gpl
	3 %	1-2 %	30 gpl	1-2 gpl

Table 3.5 recipe for unconventional dyeing

3.7.2 Procedure:

The required quantity of dyestuff is pasted with little quantity of cold water

↓

Then dilution of hot water having the temperature of about 80°c with stirring and filteration if necessary.

↓

Prepare the dye bath with the required quantity of dyestuff in 1:20 M:L:R at 40°c .enter the well scoured/bleached wetted cotton material into the hot dye bath and work the material for 15 mins.

↓

Then temperature of the bath is gradually raised to 70-80°c.after 15mins required quantity of 1st half portion of soda ash added to the dye bath for fixation.

↓

Then add the 2nd half portion of soda ash into the dye bath for fixation of the dyestuff in the fibre and work further abourt 30 mins during the addition of soda ash the dye bath temperature should not be below 80°c.

↓

Then remove the fabric from the dye bath and washed,rinsed well.

3.7.3 Soaping:

In order to remove the loosely adhered dye particles and to improve the fastness property of dyeing the material .
↓
Soaping treatment with 1-5 gpl of soap at boiling condition for 30 mins .then wash ,rinse well and dry for shade.

3.8 TESTING METHODS
The Dyed samples are tested such as washing fastness, rubbing fastness, light and perspiration fastness, Delta E value and biological oxygen demand, chemical oxygen demand and total dissolved solids as per standard methods. AATCC, ASTM, ISO Test standards are followed for analyzing the fastness properties and can be assessed by using Grey Scale.

3.8.1 Measurement of washing fastness

Principle of Testing:
A sample of textile in the form of fabric is in contact with a piece of specified adjacent fabrics in mechanically agitated in a soap or soap-soda solution, rinsed and dried. The change in colour of the specimen and the staining of the adjacent fabrics are assessed with a grey scales.

Sampling:
The sample should be a representative sample or one agreed to between the buyer and the seller.

Apparatus:
A suitable mechanical washing machine with the following requirements to be used.

Water bath containing a rotor by means of which contains 500ml capacity is rotated at a speed of 40+ revolutions/ min. The containers may be stainless steel or glass.
Means of thermostatically controlling the temperature of the water bath so as to maintain the temperature an accuracy of 40 + 2oC.

Washing test:
The washing fastness of the dyed textiles may be performed under 5 different standard test conditions as shown in the table below.

Washing Test No.	Second Adjacent fabric	Soap solution conc.	Soda ash conc.	Tempof test ^o C	Time of treatment	Steel balls of 6mm dia	M : L ratio	IS Test Number
1.	Wool 10x4cm	5 g/l	NIL	40 + 2^oC	30 min.	---	1 : 50	IS687:1979
2.	Wool 10x4cm	5g/l	NIL	50 + 2^oC	45 min.	---	1 : 50	IS3361:1979
3.	Wool 10x4cm	5 g/l	2 g/l	60 + 2^oC	30 min.	---	1 : 50	IS764:1979
4.	Viscose 10x4cm	5 g/l	2 g/l	95 + 2^oC	30 min.	10	1 : 50	IS765:1979
5.	Viscose 10x4cm	5 g/l	2 g/l	95 + 2^oC	4 hrs.	10	1 : 50	IS3417:1979

Table 3.6 Washing fastness recipe

As per the specifications the test specimens of size 10 x 4 cm is taken. Then two pieces of adjacent fabrics of 10 x 4 cm( as per the given specifications and fabrics type) are taken. Then a composite specimen is prepared by keeping the test specimen in between the two pieces of un dyed cloth and stitched around at the four edges as shown in figure. Necessary soap soda solution is prepared as per the M :L ratio 1 :50. The specimen is kept in the container of the washing machine with the soap or soap soda solution. The containers are closed and washing is carried for 30 minutes with 40 o C. Remove the composite specimen , rinse it twice in cold water and cold running water for ten minutes.

Remove the stitches along the two long sides and one short side. Open out the composite specimen and dried it in hot air oven at 60 o C or at room temperature.

Evaluation of colour fastness to washing:
The composite specimens containing the specimen is evaluated with the grey scale for a. Change in colour, b. Staining

The grey scale consists of 9 pairs of standard grey chips, each pair representing the difference in colours (shade and strength) corresponding to the numerical fastness rating. This ratings may be described in qualitative terms as follows.

Rating	Qualitative Description
5	Excellent
4 – 5	Very Good to Excellent
4	Very Good
3 – 4	Good to very good
3	Good
2 – 3	Fair to Good
2	Fair
1 – 2	Poor to fair
1	Poor

Table 3.7 grey scale rating

Similarly another set of grey scale for staining

3.8.2 MEASUREMENT OF RUBBING FASTNESS
Principle: Specimens of textiles are rubbed with dry rubbing cloth and with wet rubbing cloth by means of rubbing finger of specified dimensions. The staining of rubbing cloth is assessed with the grey scale for staining. The ratings are assessed for dry rubbing and wet rubbing fastness of the specimen.procedure followed by ISO method. [ISO-105-X12]

Sampling: The sample shall be selected so as to be the representative of sample of the lot or as agreed to between the buyer and seller.

Apparatus:

Figure3.8: Crock meter

A crock meter is used which consist of a flat surface to hold the specimen and a rubbing finger of 1.6mm diameter to have a to and fro motion in a straight line along a 10cm track on the specimen with a downward force of 9 Newton’s.

Rubbing cotton cloth: This should be bleached without any finish and cut it into a size of 5 x 5 cm.

Test Specimen: It should not be less than 14 cm x 5 cm. Two pieces are to be used one in warp way and one in weft way for dry rubbing test. Similarly for wet rubbing test two pieces are to be used.

Procedure: Fix the test specimen to the rubbing device by means of clamps such that the long direction of the specimen follows the track of the device.

a). Dry rubbing: Dry rubbing cloth is fixed flat in place of over the end of the finger of the device. Fix the test specimen to the rubbing device by means of clamps such that the long direction of the specimen follows the track of the device. Operate the apparatus and rub the test specimen to and fro in a straight line along the track to 10 times with the downward force of 9 Newton’s. Remove the test specimen out and compare it with the standard fabric for staining test. Assign the rating by using the grey scale for staining. Each test is conducted for warp and weft way directions of the fabric.

b). Wet rubbing: Fix the test specimen to the rubbing device by means of clamps such that the long direction of the specimen follows the track of the device. A standard cloth is wetted for 10 min. in a disc containing distilled water to take-up about 100%. Then it is fixed flat over the end of the finger of the testing device. Operate the apparatus and rub the test specimen to and fro in a straight line along the track to 10 times with the downward force of 9 Newton’s. Remove the test specimen out and compare it with the standard fabric for staining test. Assign the rating by using the grey scale for staining. Each test is conducted for warp and weft way directions of the fabric.

Evaluation of colour fastness to rubbing:
The composite specimens containing the specimen is evaluated with the grey scale for a. Change in colour b. Staining

The grey scale consists of 9 pairs of standard grey chips, each pair representing the difference in colours (shade and strength) corresponding to the numerical fastness rating. This ratings may be described in qualitative terms as follows.

Rating	Qualitative Description
5	Excellent
4 – 5	Very Good to Excellent
4	Very Good
3 – 4	Good to very good
3	Good
2 – 3	Fair to Good
2	Fair
1 – 2	Poor to fair
1	Poor

Table 3.9.grey scale rating for rubbing fastness testing

3.8.3 MEASUREMENT OF FASTNESS TO ALKALI, ACID PERSPIRATION:

Principle: Specimens of the Textiles in contact with adjacent fabrics are treated with two different solutions of acid and alkali immerse it for 30 minutes and the removed .The materials is uniformly squeezed and placed under a specified load for 4 hrs in between the two acrylic sheets of perspirometer for 4 hours .Then the samples are removed from the plates, stitches are removed on three sides of the samples, then dried and compared for the shade variation in the gray scales for assessment of shade variations.

Reagents: As human perspiration may be acid or alkali two solutions are prepared.

a. Alkali solution : Freshly prepared ,containing the following chemicals per litre

0.5 g of Sodium chloride (Nacl) and
5g of disodium hydrogen orthophosphate dodecahydrate

b. Acid Solution : Freshly prepared ,containing the following chemicals per litre:

5g 1- hisitidine monohydrochloride monohydrate

5g of sodium chloride and 5g of sodium dihydrogen orthophosphate dehydrate

This solution is brought to pH 5.5 with acetic acid solution.

Preparation of test Specimens:
If the textile to be tested in the form of fabric, place a specimen 10 x 4 cm in size between two 10x 4 cm pieces of the two kinds of adjacent fabrics and sew along one of the shorter sides to form a composite specimen. Two such composite specimens are required.

Procedure : Wet one of the composite specimen thoroughly in the alkaline solution using a liquor to specimen ratio of 50 : 1 and allow it to remain in the solution at room temperature for 30 minutes. press and move it from time to time to ensure good and uniform penetration of the liquor .Pour off the liquor and wipe the excess liquor offthe specimen between two glass rods.

Then palce the composite specimen between two glass or acrylic resin paltes under a force of 5.1 kgs (as the specimen is 10 x 4 cm in size ) in a perspirometer.Keep the perspirometer in the air oven at 37 + /- 2 ○C for hours.

Open out the composite specimen by breaking the stitches on all the sides except one of the shorter sides. Dry the three parts in air at temperature not more than 60°C

With the three parts in contact only at the remaining line of stitching.

Treat the second composite in acid solution as noted above instead of alkaline solution. Evaluate the change in colour of the treated test specimens and the degree ofstaining of the two pieces of adjacent fabric with help of the grey scale and assign theratings, taking care to first cool the test specimens and the adjacent fabrics to room temperature. In case of doubt in the rating given by an observer, the accessestment should be done by at least three observers and the overall average rating should be reported.

Figure 3.10: Perspirometer

Similarly another set of grey scale for staining

The test specimen is evaluated for staining and then ratings are accessed.

3.8.4 MEASUREMENT OF LIGHT FASTNESS
Dyed or Printed material is exposed in day light / artificial xenon arc lamp light to assess the Light fastenss Property.It is assessed on a scale of eight (1……..8): 1 representing the least fastness and 8 the best.

Principle:
A specimen of the textile is exposed to day-light under prescribed conditions, including protection from rain, along with eight dyed wool standards. The fastness is assessed by comparing the change in color of the specimen with that of the standards.

Blue wool standards produced in Europe are identified by the numerical designation 1 to 8. These standards are blue wool cloths dyed with the dyes listed below. The range from 1 (very low light fastness) to 8 (very high light fastness)

List of standard wool dyes:

S.No	LF dye rating	CI Designation	Chemical class
1	Acilan Brilliant Blue FFR	CI Acid Blue 104	Triaryl methane
2	Acilan Brilliant Blue FFB	CI Acid Blue 109	Triaryl methane
3	Coomassie Brilliant Blue R	CI Acid Blue 83	Triaryl methane
4	Supramine Blue EG	CI Acid Blue 121	Azine
5	Solway Blue EG	CI Acid Blue 47	Anthraquinonoid
6	Alizarin Light Blue 4GL	CI Acid Blue 23	Anthraquinonoid
7	Soledon Blue 4 BC pdr	CI Solublised Vat Blue 5	Indigoid
8	Indigosol Blue AGG	CI Solublised Vat Blue 8	Indigoid

Table 3.11 List of standard wool dyes

The dyeing strength in both of the standard systems of 1 to 8 are omitted because of certain manufacturing problems but the sets of the standard dyeing are marketed after getting them matched in depth of shade and fading rate with those of the master set.

Assessment of light fastness:
Compare the change in color of the test specimen with the changes which have occurred in the standard patterns. The light fastness of the specimen is the number of the standard pattern which shows similar changes in color (Visual contrast between the exposed and unexposed portions of the specimen). If the specimen shows changes in color, approximately half way between two standards, half rating may be given for eg, 3 – 4.

Figure 3.11: Grey scale

Table 3.12. Fastness raing

3.8.5 COMPUTER COLOUR MATCHING
Colour can be defined as the effect on the brain of an observer when an object is viewed in the presence of a light source.

In textile industries, the desired color is obtained by mixing three or four dyes. The most important problem in the industry is how to arrive at the perfect match to the customer’s samples using minimum amount of chemicals and dyes. This job is normally attended by an expert dyeing master who decides the three or four dyes color recipe to reproduce a given shade. The dyeing master maintains the record of his experience in “shade Bank” and selects one of the color recipes, which may be close to the standard. He, then, makes necessary changes by trial and error method to obtain the exact match.most appropriate recipe depending on the cost of production and quality of the products required. This technique is known as Computer Aided Color Matching.

A computer colour matching system comprises of,

A spectrophotometer
A personnel computer
A colour matching software

A spectrophotometer is an instrument which measures colour of an object. To measure colour of an object we use reflectance spectrophotometer. The spectrophotometer consist of light source, integrating sphere, dispersion device, detector, signal processor or microprocessor

Light source:
The light source illuminates the specimen. The light source used in spectrophotometers are tungsten halogen, xenon flash, light emitting diode, emits the light in the visible region.

Integrating sphere: It is coated with barium sulphate, to simulate the conditions of daylight

Dispersion device (prism): It splits the light in to various colours.

Detector:
A sensor which detects energy of the light source that is reflected back by object

Signal processor or microprocessor:
In optical sensor the electrical signal is generated proportional to light energy reflected from the sample. These electrical signals corresponding to different wavelengths are fed to microprocessor. The microprocessor converts the analogue signal from optical sensor into digital form to compute and display several colour parameters following CIE recommendations. (CIE- commission International del’Eclairage or International Commission of Illumination).For textile Samples the measurements in a spectral range from 400 to 700nm at 20nm interval is used.

The colour matching software consist of the following modules / programmes:

Quality assurance:
All QA applications involve comparing batches against a standard.

QA functions in the following applications:

colour difference assessment for approved standard and a batch
whiteness / yellowness index for assessing whiteness of OBA treated samples and yellowness for white textile substrates.
pass / fail status for batch production

K/S Data generation:
Generate K/S data using representative substrates and processes. Analyses K/S data outputs for various colorant properties

Formulation:
Match new as well as current shades and obtain formulation for cost saving. It performs colour matching for a given target using selected dyes.

Batch correction: Use batch correction for laboratory and production correction. It will help in reducing trail and error method.

Colour maker:
Use colour maker program for generating new shades.

Shade Library:
Stores all lab and productions shades into computer.

File management:
Use file management for creating a user data. keep back up of data files using this program.

Instrument :

Figure 3.13.Computer colour matching instrument

Select instrument using setup. Calibrate spectrophotometer and set communication codes between computer and instrument.the final delta E value calculated by ccm software.

3.8.6 MEASUREMENT OF BIOLOGICAL OXYGEN DEMAND (BOD)

BOD:
Biological oxygen demand is the amount of dissolved oxygen needed(i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at a certain temperature over a specific time period.

Apparatus:

Incubator
Burette
Pipette
Conical flask
BOD bottles

Chemical required:

Manganese,sulphate
Sodium azide
Potassium iodide
Sodium hydroxide
Starch,potassium fluoride
Sodium thiosulphate

Theory:
BOD is the amount of oxygen utilized by microorganisms in biological process that break down organic matter in water.it is a measure of organic pollutant load.greater the oxidizable organic matter in water,the greater will be the BOD,thus ,the strength of waste is expressed in terms of BOD. BOD, is important to know the amount of organic matter present in the waste and that the quantity of oxygen required for its stabilization .the BOD values are thus very useful in process designed to measure treatment plant efficiency and operation.

The origin of organic compounds are complete the human excreta,vegetables,animal waste, and industrial waste.the amount of organic matter present in water shows the amount of biological oxygen demand. large amount of sewage introduced into water body do not get diluted sufficiently. Microorgnisms use up all the oxygen in the water to oxidize organic matter as a result of which water becames useless for drinking and for the other purposes.

The complete degradation of organic matter may take 20 to 30 days .simple organic compounds like glucose are almost completely oxidized in 5 days while domestic sewage is oxidized to 65 %in this period. Complex organic compounds get oxidized only upto 40% in the same period. The 20 to 30 days period is of least significance in practice.therefore ,the BOD test has been developed for 5 days at 20°c .BOD in general gives a qualitative index of organic substance which are degraded quickly in a short period time.

The BOD value is measure by measuring the difference of dissolved oxygen (DO) of the same water sample in 5 days.DO present in water is calculated by using the formula.

Dissolved oxygen (mg/l) = ( A.N.8 ) /(S-C) ×1000

Where,
A = ml of 0.025 N thiosulphate solution consumed
N = normality of standard thiosulphate solution
C = Total volume of potassium manganese, sulphate, alkali iodide azide, Potassium fluoride
S = volume of water sample

Procedure:
The water samples was collected in two bottles .one BOD bottle was incubated in BOD incubator for 5 days or 3 days at 20*c while DO of another BOD was determined on the 1 st day. After 5 days or 3 days ,another BOD bottles was removed from the incubator and DO was determined.difference in DO was calculated ,which gave the measure of BOD.

Calculation:

BOD of water is calculated by using the formula,

                        DO 1 – DO 5
BOD (mg/l) = ------------------------
                                P

Where,
DO 1-DO in water sample in 1 st day.
DO 5- DO in water sample in 5 days.
P = decimal volumetric fraction

                                             A.N.8
Dissolved oxygen (mg/l) = ------------------ × 1000
                                             S – C

Where,
A = ml of 0.025 N thiosulphate sil.consumed
N = normality of standard thiosulphate solution
C = Total volume of potassium manganese, sulphate alkali iodide azide, Potassium fluoride
S = volume of water sample

3.8.7 MEASUREMENT OF CHEMICAL OXYGEN DEMAND (COD)

Introduction:
Chemical Oxygen Demand (COD) test determines the oxygen requirement equivalent of organic matter that is susceptible to oxidation with the help of a strong chemical oxidant. It is an important, rapidly measured parameters as a means of measuring organic strength for streams and polluted water bodies. The test can be related empirically to BOD, organic carbon or organic matter in samples from a specific source taking into account its limitations. The test is useful in studying performance evaluation of wastewater treatment plants and monitoring relatively polluted water bodies. COD determination has advantage over BOD determination. COD results can be obtained in 3-4 hrs as compared to 3-5days required for BOD test.

Open Reflux method

Principle
The open reflux method is suitable for a wide range of wastes with a large sample size. The dichromate reflux method is preferred over procedures using other oxidants (e.g. potassium permanganate) because of its superior oxidizing ability, applicability to a wide variety of samples and ease of manipulation. Oxidation of most organic compounds is up to 95-100% of the theoretical value.

The organic matter gets oxidised completely by potassium dichromate (K2Cr2O7) with silver sulphate as catalyst in the presence of concentrated H2SO4 to produce CO2 and H2O. The excess K2Cr2O7 remaining after the reaction is titrated with ferrous ammonium sulphate [Fe (NH4)2(SO4)2]. The dichromate consumed gives the oxygen (O2) required for oxidation of the organic matter. The chemical reactions involved in the method are as under:

a. 2K₂Cr₂O₇+ 8 H₂SO₄® 2 K₂SO₄+ 2Cr₂(SO₄)3 + 8 H₂O + 3O

b. C₆H₁₂O₆+ 6O₂® 6CO₂+ 6H₂O

c. Cr₂O7^--+ 6Fe⁺⁺+ 14H⁺® 6Fe⁺⁺⁺+ 2Cr³⁺+ 7H₂O

Apparatus and equipment

250 or 500mL Erlenmeyer flask with standard (24/40) tapered glass joints
Friedrich’s reflux condenser (12 inch) with standard (24/40) tapered glass joints
Electric hot plate or six-unit heating shelf
Volumetric pipettes (10, 25, and 50mL capacity)
Burette, 50mL with 0.1mL accuracy
Burette stand and clamp
Analytical balance, accuracy 0.001g
Spatula
Volumetric flasks (1000mL capacity)
Boiling beads, glass
Magnetic stirrer and stirring bars.

Reagents and standards

a. Standard potassium dichromate solution, 0.25N (0.04167 M): Dissolve 12.259g K2Cr2O7 dried at 103°C for 24h in distilled water and dilute to 1000mL. Add about 120mg sulphamic acid to take care of 6 mg/L NO2 – N.

b. Sulphuric acid reagent: Add 10g of Ag2SO4 to 1000mL concentrated H2SO4 and let stand for one to two days for complete dissolution.

c. Standard ferrous ammonium sulphate approx. 0.25N (0.25M): Dissolve 98g Fe(NH4)2(SO4)2.6H2O in about 400mL distilled water. Add 20mL concentrated H2SO4 and dilute to 1000mL.

d. Ferroin indicator: Dissolve 1.485g 1, 10-phenanthroline monohydrate and 695mg FeSO4.7H2O in distilled water and dilute to 100mL.

e. Mercuric Sulphates: HgSO4, crystals, analytical grade

f. Potassium hydrogen phthalate (KHP) Standard: Dissolve 425mg lightly crushed dried potassium hydrogen phthalate (HOOC.C6H4.COOK) in distilled water and dilute to 1000mL. This solution has a theoretical COD of 500μg O2/mL. This solution is stable when refrigerated, up to 3 months in the absence of visible biological growth.

Sample collection, preservation and storage
Preferably collect samples in glass bottles. Homogenise samples containing settleable solids. If there is delay in collection and analysis, preserve sample by acidification to pH≤2 using concentrated H2SO4. Samples can be preserved for maximum 7 d.

Procedure

Sample preparation: All samples high in solids should be blended for 2 minutes at high speed and stirred when an aliquot is taken for analysis. Select the appropriate volume of sample based on expected COD range, e.g. for COD range of 50-500 mg/L take 25-50mL of sample. Sample volume less than 25mL should not be pipetted directly, but serially diluted and then a portion of the diluted sample taken. Dilution factor should be incorporated in calculations.

500mL of sample diluted to 1000mL = 0.5mL sample/mL of diluent, 50mL = 25mL of sample.
100mL of sample diluted to 1,000mL = 0.1mL sample/mL diluent, 50mL of diluent = 5mL of sample.

Reflux of samples:

Place 0.4g HgSO4 in a 250mL reflux sample
Add 20mL sample or an aliquot of sample diluted to 20mL with distilled water. Mix well.
Add clean pumic stones or glass beads.
Add 10mL 0.25N (0.04167M) K2Cr2O7 solution and mix.
Add slowly 30mL concentrated H2SO4 containing Ag2SO4 mixing thoroughly. This slow addition along with swirling prevents fatty acids to escape due to generation of high temperature. Alternatively attach flask to condenser with water flowing and then add H2SO4 slowly through condenser to avoid escape of volatile organic substance due to generation of heat.
Mix well. If the colour turns green, either take fresh sample with lesser aliquot or add more potassium dichromate and acid.
Connect the flask to condenser. Mix the contents before heating. Improper mixing will result in bumping and blow out of flask content.
Reflux for a minimum of 2 hours. Cool and then wash down condenser with distilled water.
Disconnect reflux condenser and dilute the mixture to about twice its volume with distilled water. Cool to room temperature and titrate excess K2Cr2O7 with0.1M FAS using 2-3 drops of ferroin indicator. The sharp colour change from blue green to reddish brown indicates end-point or completion of the titration. After a small time gap, the blue-green colour may reappear. Use the same quantity of ferroin indicator for all titrations.
Reflux blank in the same manner using distilled water instead of sample.

Alternate procedure for low COD samples less than 50mg/L: Follow similar procedure with two exceptions (i) use standard 0.025N (0.004167M) K2Cr2O7 and (ii) titrate with standardize 0.025M FAS. The sample volume should be 5.mL. Exercise extreme care with this procedure because even a trace of organic matter on the glassware or from the atmosphere may cause gross errors. Compute amount of HgSO4 to be added based on chloride concentrations. Carry blank reagent through the same procedure.

Calculations

COD as mg/L = (a –b) x N x 8000 / mL sample

Where,

a = mL FAS used for blank
b = mL FAS used for sample
N = normality of FAS
8000 = Milieq. wt. of O2 x 1000

3.8.8 MEASUREMENT OF TOTAL AND DISSOLVED SOLID FROM EFFLUENT WATER SAMPLE

Total dissolve solid
Total Dissolved Solids (often abbreviated TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid like molecular, ionized or micro-granular (colloidal sol) suspended form. The total dissolved solids are small enough to filter through a sieve the size of two micrometer.

Total dissolved solids parameters are applied for freshwater systems, as salinity comprises some of the ions constituting also define as TDS. The principal application of TDS is in the study of water quality for streams, rivers and lakes, although TDS is not generally considered a primary pollutant parameter because it is not directly associated with health effects. Generally it is an indication of aesthetic (visual) characteristics of drinking water and as an aggregate indicator of the presence of a broad group of chemical contaminants.

Sources of TDS
Primary sources for TDS in receiving waters are Dyeing outlet water and water runoff, leaching of soil contaminant and effluent discharge from industrial or sewage treatment plants. The most common chemical constituents are calcium, phosphates, nitrates, sodium, potassium and chloride, which are found in nutrient runoff and water runoff.

Measurement of TDS
The two principal methods of measuring total dissolved solids are gravimetric and conductivity. Gravimetric methods are the most accurate and involve evaporating the liquid solvent to leave a residue that can subsequently be weighed with a precision analytical balance (normally capable of 0.0001 gram accuracy). This method is generally the best, although it is time-consuming and leads to inaccuracies if a high proportion of the TDS consists of low boiling point organic chemicals, which will evaporate along with the water. If inorganic salts comprise the great majority of TDS, gravimetric methods are appropriate.

Electrical conductivity of water is directly related to the concentration of dissolved ionized solids in the water. Ions from the dissolved solids in water create the ability for that water to conduct an electrical current, which can be measured using a conventional conductivity meter or TDS meter. When correlated with laboratory TDS measurements, conductivity provides an approximate value for the TDS concentration, usually to within ten-percent accuracy. (A) Total Solids

These are the measure of the amount of all kinds of solids. i.e. Suspended, dissolved, volatile etc. in effluent water sample. Total solids can be measured as the residue left after evaporation of the unfiltered sample.

Procedure

Take an evaporating dish and dry it till constant weight and note down the weight of evaporating dish.
Take 50 ml of unfiltered well shaken water sample in evaporating dish.
Put it on water bath for evaporation or heat at 105'c for 1 hour in an oven.
After all water is evaporated form the evaporating dish, put evaporating dish in decicator for cooling for one hour.
Take final weight of evaporating dish and calculate total solids by given formula

Observation and calculation for total solids:

Initial weight of the evaporating dish (g) = A
Final weight of the evaporating dish (g) = B
Volume of the sample evaporating (ml) = V

Total solids (TS) as mg/l = (B –A )×1000×1000 / V

CHAPTER 4

RESULTS AND DISCUSSIONS
Cotton fabric are pretreated with polyacrylamide solution and dyed with hot brand reactive dyes using salt and without salt. the test results are discussed here with different testing results like washing, rubbing, light, perspiration fastness and total dissolved solids(TDS),biological oxygen demand(BOD),chemical oxygen demand(COD).

4.1 WASHING FASTNESS

The washing fastness of the samples was tested by using launder meter.

Sl.no	Samples	Dyes %	Rating (conventional)	Rating (unconventional)	Description
1	RED HE3B	1%	3-4	4	Moderate to good
		2%	4	4-5	good
		3%	4	4-5	Good
2	RED HE5B	1%	4	3-4	Moderate to good
		1%	3-4	4	Moderate to good
		2%	3-4	5	Good
		3%	4	4-5	Good
3	YELLOW HE4R	1%	4	3-4	Moderate to good
		2%	4-5	4	Good
		3%	4-5	5	Very good
4	NAVY BLUE HEGN	1%	3-4	4	moderate
		2%	4-5	4-5	Moderate to good
		3%	4	5	Good
5	BLUE HEGN	1%	3-4	4	Moderate to good
		2%	4	4-5	Good
		3%	4-5	4-5	Good

Table 4.1.washing fastness rating for conventional and unconventional dyeing

Figure 4.2 .Washing fastness rating value of dyed sample

4.2 RUBBING FASTNESS
The rubbing fastness of the samples was tested by using crock meter.

Sl.no	Samples	Dyes %	Rating (conventional)		Rating (unconventional)		Description
Sl.no	Samples	Dyes %	Dry	Wet	Dry	Wet	Description
1	RED HE3B	1%	4	2-3	4	3	Moderate to good
		2%	4	3	4-5	3	Good
		3%	4-5	3-4	4-5	3-4	Good
2	RED HE5B	1%	4	3	4	3	good
		2%	4-5	3-4	5	3-4	Moderate to good
		3%	4	3-4	4-5	3-4	good
3	YELLOW HE4R	1%	4-5	3	5	3	Moderate to good
		2%	5	3	4-5	3	Good
		3%	5	3-4	5	3-4	Good
4	NAVY BLUE HEGN	1%	4	3	4	3	moderate
		2%	4-5	2-3	4-5	2-3	good
		3%	5	3	4-5	3	good
5	BLUE HEGN	1%	4	3	4	3	Good
		2%	4-5	3-4	4-5	3-4	Moderate to good
		3%	4-5	3	4-5	3-4	Good

Table 4.3: Rubbing fastness rating for conventional and unconventional dyeing

Figure 4.4.Rubbing fastness rating value difference of dyed sample

4.3 LIGHT FASTNESS
The light fastness of the samples was tested by day light.

Sl.no	Samples	Dyes %	Rating (conventional)	Rating (unconventional)	Description
1	RED HE3B	1%	6	5-6	good
		2%	6	6	Very good
		3%	5-6	6-7	good
2	RED HE5B	1%	6	6	Very good
		2%	6	6-7	good
		3%	6	6	good
3	YELLOW HE4R	1%	5-6	5-6	good
		2%	6	6-7	good
		3%	6	6-7	Very good
4	NAVY BLUE HEGN	1%	6	6	good
		2%	5-6	6	good
		3%	6	6-7	Very good
5	BLUE HEGN	1%	6	6	good
		2%	6	6-7	Very good
		3%	6	6	good

Table 4.5.light fastness rating for conventional and unconventional dyeing

Figure 4.6 Light fastness rating difference of dyed sample.

4.4 PERSPIRATION FASTNESS
The perspiration fastness of the samples was tested by using perspirometer.

Sl.no	Samples	Dyes %	Rating (conventional)		Rating (unconventional)		Description
Sl.no	Samples	Dyes %	Acid	Alkali	Acid	Alkali	Description
1	RED HE3B	1%	4	3-4	4	3-4	Moderate to good
		2%	3-4	4	4-5	4-5	Very good
		3%	4	4	4	4	good
2	RED HE5B	1%	4	4-5	4	4-5	Very good
		2%	4	4	4	4	Good
		3%	5	4	4-5	4	Good
3	YELLOW HE4R	1%	4	3-4	4	3-4	Good
		2%	3-4	4-5	3-4	4-5	Moderate to good
		3%	4	4	4	4	Very good
4	NAVY BLUE HEGN	1%	5	3-4	5	3-4	Good
		2%	4	4	4	4-5	Good
		3%	3-4	4	4	4	Very good
5	BLUE HEGN	1%	5	4-5	5	4-5	Good
		2%	4	4	4	4	Very good
		3%	4	3-4	4	3-4	Good

Table 4.7.Perspiration fastness rating for conventional and unconventional dyeing

Figure 4.8: Perspiration fastness rating difference of dyed sample.

4.5 COLOUR STRENGTH MEASUREMENT:
The colour strength of the samples was tested by using spectrophotometer.the delta E is a metric for understanding how the human eye perceives colour difference.Delta E is a single number representing the “distance” between two colours.this value measured from reference sample(conventional dyed sample using salt) and target (unconventional dyed sample without salt) sample.

Sl.no	Samples	Shade %	Between Delta E (conventional &unconventional dyed sample)
1	Red HE3B	1%	0.48
		2%	0.70
		3%	0.59
2	Red HE5B	1%	0.67
		2%	0.58
		3%	0.62
3	Yellow HE4R	1%	0.53
		2%	0.72
		3%	0.56
4	Navy blue HEGN	1%	0.58
		2%	0.49
		3%	0.68
5	Blue HEGN	1%	0.54
		2%	0.57
		3%	0.60

Table 4.9 Delta E of dyed sample using salt and saltfree dyed sample

Figure 4.10: Delta E value difference of fabric

4.6 BIOLOGICAL OXYGEN DEMAND:
Biological oxygen demand is the amount of dissolved oxygen needed (i.e demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.The BOD of the samples was tested by using Titrimetric metod.the BOD level of conventional dyeing and unconventional dyeing are shown in below.

BOD value of dyedoutlet water sample:

Sl..No	BOD 3 days	Conventional Dyeing Outlet - Water Sample	Un Conventional Dyeing Outlet - Water Sample
1	Biological Oxygen Demand, mg/l 27 deg C, 3 days	710 mg/l	440 mg/l

Table 4.11 . BOD value of dyed outlet water sample

Figure 4.12: BOD value difference of dyed outlet water sample

4.7 CHEMICAL OXYGEN DEMAND(COD):
Chemical oxygen demand(COD) is a measurement of the oxygen required to oxidize soluble and particulate organic matter in water.this value indicate the amount of oxygen needed to oxidize all organic substance in water.

The COD of the samples was tested by using Open Reflux method .the COD level of conventional dyeing and unconventional dyeing are shown in below.

COD value of dyed outlet water sample:

S.NO	COD	Conventional Dyeing Outlet - Water Sample	Unconventional Dyeing Outlet - Water Sample
1	chemical Oxygen Demand, mg/l	9500 mg/l	6550 mg/l

Table.4.13 COD value of dyed outlet water sample

Figure 4.14: COD value difference of dyed outlet water sample

4.8 TOTAL DISSOLVED SOLIDS(TDS) MEASUREMENT:
The total dissolved solids(TDS) value of the samples was tested by using TDS meter.

Sl.no	Dyed outlet water	TDS (ppm) (conventional dyed water sample value)	TDS (ppm) (unconventional dyed water sample value)
1	RED HE3B	12000	6000
2	RED HE5B	12400	6200
3	YELLOW HE4R	13000	6300
4	NAVY BLUE HEGN	12800	6000
5	BLUE HEGN	13000	6100

Table 4.15 TDS value rating inconventional dyeing and unconventional dyeing

Figure 4.16. TDS value difference of dyed outlet water sample

CHAPTER 5

CONCLUSION
In my project, the Cotton fabrics were pretreated with polyacrylamide, then reactivity of reactive dyes on fibre increased. then the fabric are dyed using reactive dyes without salt. The dyeing of cotton with reactive dyes using polyacrylamide pretreated fabric in the dye bath improves the dye ability of cellulosic fabrics with reactive dye, when dyeing the modified substrates.the reactive dyes can be much more efficiently exhausted and fixed onto cellulosic fabrics under neutral conditions in the absence of salt .

Then Washing fastness , rubbing fastness,light fastness and perspiration fastness of pretreated sample were better than that for the conventionally dyed sample. The pretreated sample increases the dye uptake as well as deep colour yield delta-E value .The total dissolved solid (TDS) content of the dyed outlet water efficiently reduced than conventional dyeing process. The biological oxygen demand (BOD) and chemical oxygen demand (COD) of dyed outlet water also controlled and reduced than conventional method dyeing. By using this pretreatment method, the following advantages were observed:

Elimination of salt as an electrolyte,
Maximum fixation of dye,
Minimum hydrolysis of dye,
Low volume of water requirement during the wash-off process,
Significant savings in process costs,
Environmentally friendly.

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Now You Know Salt Free Dyeing of Cotton Fabric with Reactive Dyes

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