The Presentation

On

“ECO FRIENDLY TEXTILE PROCESSING”UNDER THE GUIDANCE OF

Prof. (Dr.) M.D.TELI BY

Omkar S. ParmajAlemayehu Leta

A good preparatory process has several objectives

•Removal of loose hairy protruding fibres from the surface of the fabric to give a smooth, even and clean looking face.

•Removal of natural impurities like oils, fats, waxes, greases, natural matter, lignin and sizing material like starches.

•To obtain an absorbent fabric,this is ready for dyeing or printing process.

•To obtain softer and proper white fabric, depending on its application.

INTRODUCTION

Singeing Desizing Scouring and Bleaching

Merserization DyeingFinishing

PROCESS SEQUENCE FOR PRETREATMENT

The process of singeing is carried out for the purpose of removing the loose hairy fibres protruding from the surface of the cloth, thereby giving it a smooth, even and clean looking face.

Objective if singeing machine•Removing of protruding fibre•Improving luster•Reduce dyeing and printing problem

Types of singeing process1. Plate singeing machine 2. Rotary-cylinder singeing machine3. Gas singeing machine

SINGEING

•Material ofburner: metal replaced by ceramic.

•Composition of gas fuel: air to petroleum chemical ratio

•Fabric is pre heated to remove the moisture.

•Water cooling system is incorporated just behind the ceramic material to control the temperature of ceramic material.

•in case of power failure, both burners tilt away from the fabric simultaneously.

•Fabric passing path is variable for maintaining contact angle for different kind of fabric.

ADVANCEMENT IN SINGEING

Eco friendly pre-treatmentEco friendly pretreatment carried out by enzymatic processEnzymes are a class of proteins that function as biocatalysts which are biodegradable, very specific in action and are used in small quantities. They are made up of 200-250 amino acids. They work by lowering the activation energy of the reaction making it much faster.• They are produced by living organisms such as fungi or

bacteria.• Enzymes are complex organic, soluble bio-catalysts, formed by

living organisms that catalyze chemical reaction in biological processes.

• Enzymes are quite specific in their action on a particular substance.

Enzyme EffectAmylase Desizing (to decompose starches applied in sizing)

Catalase Act on H2O2 to decompose it into water & oxygenProteases, lipases and pectinases When combined, act on proteins, pectin and natural

waxes to effect scouringLaccases Decomposes indigo molecules for wash-down effect on

denim Cellulases Break down cellulosic chains to remove protruding fibres

by degrading &create wash-down effect by surface etching on denims etc.

Cellulases and Hemicellulases Bio stoning of jeans Desizing of CMC Stylish effect on cellulose fibres

Pectinases Breaks down pectin in scouring Proteases Scouring of animal fibres, degumming of silk and

modification of wool properties Lipases Elimination of natural triglycerides (in scouring) or

present in desizing (tallow compounds)

Enzymes for textile processing

E + S → E S → P + E (Enzyme) (Substrate) (Enzyme-Substrate) (Product) (Enzyme)

Substrate entering In active side of enzyme

Enzyme substratecomplex

Enzyme/substratecomplex

Prodcut release fromenzyme

ENZYME WORKING MECHANISM

The removing of size material which incorporated in pre-weaving process is known as desizing.

DESIZING

There are three main advanced desizing method are

1. Enzymatic desizing2. Solvant desizing3. Atmospheric plasma desizing

ADVANCEMENT IN DESIZING

•Amylases are the enzyme that hydrolyses and reduces the molecular weight of cellulose.

hydrolyze starch molecules to give diverse products.

specific for starch, removing it without damaging to the support fabric.

optimum temperature is 30-60°C, optimum pH is 5.5-6.5.

ENZYMATIC DESIZING

Cont…Enzymatic desizing and utilisation of desizing liquor for H2O2

To utilize desizing baths for bleaching in which glucose oxidase enzymes generate hydrogen peroxide and gluconic acid using glucose as a substrate.

Amyloglucosidases are enzymes used in desizing to degrade starch until it becomes glucose.

Optimum conditions are 0.75% (o.w.f.) enzyme, pH 4.1, 62 °C and a process time of 45 minutes.

Advantages: reducing the use of per oxide stabilizing agents with the help of gluconic

acid saving water and energy by using desizing liquor for bleach.

• Some solvent are used for desizing of textile substrate.

• Sonafab 1000). It is a unique Desizing Agent, having excellent solvent and emulsifying action on all types of stain. (Sonal Dye-ChemPvt. Ltd)Perchloroethylene -- desizing solvent

SOLVANT DESIZING

DIFFERENT SOLVENTS USE IN DESIZING

•It is a very clean operation with no disposal problem, the pollution effect is negligible.•The time of desizing and floor area for the machinery is far less than for conventional system.•Due to quick and even solvent penetration the size removal is more uniform.•The solvents are recoverable and have less or no effluent load.•This method is useful since energy consumption is low, time of desizing is low.•Acrylic and wool fabrics develop a lustrous, soft hand in solvent without any felting.•When solvent desizing is followed by bleaching, the caustic scouring is omitted since pectin and wax

ADVANTAGES OF SOLVENT DESIZING

DISADVANTAGE OF SOLVENT DESIZING

•Although solvent desizing ranges are available commercially, the price of the equipment is high.

• The majority of size systems used in aqueous process is not readily applicable in solvent desizing.

•Cost of processing is higher than for water base process.

• Plasma is four states of matter• Here material having in ionized condition • Plasma is produce by applying electric field

on a gas• Plasma is etching the fabric surface• Etching is depend upon the voltage, type of

gas, time

ATMOSPHERIC PLASMA DESIZING

Ultrasonic energy are the high frequency waves rangeing from 20Khz to 50Mhz which is nnot audiable by human

• In liquids, longitudinal vibrations of molecules generate compression and rarefaction, i.e., areas of high pressure and low local pressure• The latter gives rise to cavities or bubbles, which expand and finally during the compression phase, collapse violently generating shock waves.• The phenomena of bubble formation and collapse (known as cavitation) is generally considered responsible for most of ultrasonic physical and chemical effects observed in solid/liquid or, liquid/liquid systems.

ULTRASONIC DESIZING

Use of ultrasonic energy in desizing Amylase - 0.75 g/l wetting agent - o.5 g/l Temperature - 55°C Time - 20 min.Desizing efficiency 7 when US is used.Desizing efficiency 2.5 when US is not used.

•Energy savings resulting from lower process temperatures and shorter cycle times• Reduced consumption of dyes and chemicals, which allows for a 20-30% reduction in the amount of effluent • Water savings of around 20% • Improvement in product quality • Increased productivity because of shorter cycle times

Limitation•This process requires some assistance from temperature. This process does not involve complete elimination of temperature.

Recipe Advantage

ADVANTAGES OF ULTRASONIC

To remove natural as well as added impurities of essential hydrophobic character(oil,fat,waxes) as completely as possible and leave the fabric in high absorptive condition without undergoing significant chemical or physical damage To make the goods suitable for removing the natural colouring matter of the cotton during the subsequent bleaching process.

Conventional method: Alkali scouring.Where 3-4% caustic soda is used at high temperature (90-95oC) for long duration (2-3hours)

Disadvantages of alkali scouring:1) Damage to fibre.2) Requirement of large quantity of water for washing.3) Heavy effluent load (Salts of neutralization)

SCOURING

Enzymatic Scouring or Bio-Scouring can simply be defined as the application of living organisms and their components to remove the natural and added impurities.

Enzymes used for Bio scouringPectinase – (Pectins removal)Protease – (Removal of proteins)Combination of 2 or 3 enzymes may be used to get synergistic effect.

Conventional scouring requires high temperatures and high consumption of chemicals. Suppliers.

BIO SCOURING

Parameter Bio Scouring Alkaline Scouring

pH 7-8 12-13

Temperature 50-600C 950C

Residual Pectin 20-25% 10-11%

Weight loss <1.5% 4-6%

Handle Very soft Harsh and papery

Rinse Water Consumption

30-40% of Alkaline scouring

TDS 50% of Alkaline Scouring

BOD 50% of Alkaline Scouring

COD 50% of Alkaline Scouring

Comparison between Bioscouring& Conventional scouring

COMPARISION OF Ph VALUE

Advantages of bi-scouring

(BOD) and (COD) of enzymatic scouring process are 50 % as compared to alkaline scouring (100 %). Total Dissolved Solid (TDS) of enzymatic scouring process is 50% as compared to alkaline scouring (100%).Handle is very soft in enzymatic scouring.It also minimises health risks of operators as they are not exposed to hazardous chemicals. reduced water and wastewater costs, reduced treatment time and lower energy consumption because of lower treatment temperature (the optimal temperature is from 40 to 60°C) .

ADVANTAGES AND LIMITATION OF BIOSCOURING

Limitation of Bio scouring process

•The enzymes used for scouring are costly and they require temperature for their action.•The increase in temperature or pH may deactivate the enzyme which may alter the process efficiency.

LIMITATION OF BIOSCOURING

BLEACHINGBleaching is to decolourise natural pigments and to confer a pure white appearance to the fibres. The most common industrial bleaching agent is hydrogen peroxide, which is usually applied at alkaline pH and temperatures close to boiling.

BIO BLEACHING

Enzymes can also be used in bleaching.Glucose oxidase Glucose oxidases (GODs) are flavoproteins with a Flavin-adenine-

dinucleotide (FAD) active site.

The enzyme is highly specific for B-D-glucose and catalyses the following

reaction for hydrogen peroxide generation.

Ph - 4.5-7

temperatures - 40°C

Cont….• Gluconic acid acts as bleach stabilizer• it would allow for the reuse of sugar contaminated effluent from

other wet processing steps (desizing bath containing glucose)

The actual bleaching process involves 2 steps: • Peroxide generation by GOD at the enzyme optimum

conditions.

• PH adjustment to 7.5-8 and bleaching process at 85-90°C for 60-120 minutes with the enzymatically hydrogen peroxide. 

Cont…LaccaseLaccase (EC 1.10.3.2) is a multi-copper oxidase enzyme which oxidizes a broad range of aromatic compounds as substrates and oxygen as a terminal electron acceptor.

Rapid bleaching with laccase–hydrogen peroxide enhances the whiteness of cotton fabrics.

Bleach clean-up Traditional method: 

Bleach --> Rinse --> Rinse --> Rinse --> Dye 

There are two methods for bleach clean-up• After completion of the process the bleached liquor was drained out, then the

fabric was rinsed with water a number of times to remove the H2O2 from the bleached fabric.

• use of a mild reducing agent to neutralise the bleach.

Cont… Catalase have been used to decompose residual hydrogen

peroxide in fabric prior to dyeing

Catalase enzyme catalyzes the decomposition of hydrogen peroxide to water and oxygen. One catalase molecule can convert millions of molecules of hydrogen peroxide to water and oxygen each second

Use of Catalase enzyme made it possible to reduce the temperature and volume of the second wash after bleaching from 80-950C to 30-400C, resulting in a 9-14% saving of energy, a 17-18% saving of water and an overall cost saving of 9%

OZONE BLEACHING Industrial production of ozone can be accomplished by applying a plasma discharge to oxygen in air. Ozone is a natural substance and it is a strong oxidising agent and it decomposes rapidly.

Process

Fabric having 24% moisture content is placed in application chamber and exposed to 100 g/m of concentration of ozone oxygen gas mixture. pH – 5 with acetic acid Time – 1-7 minTemperature- 30°C

ADVANTAGES AND LIMITATION OF OZONE BLEACHING

AdvantagesThe quality of the processed fabric is comparable.Grey preparation with ozone can be completed in one or two minute.This process has additional advantages such as savings in thermal energy, water and chemicals

Limitations The yield of ozone generator is low (6-12% from oxygen and 4-6% from air), and ozone concentration is low as well. Ozone has to be generated on-site because its problems to be stored and transported. Energy consumption for production of O3: Based on pure oxygen, the costs will be 6 to 15 kWh/kg O3.

PER ACETIC ACID BLEACHING

• Per acetic acid is also known as peroxyacetic acid.

• It is colorless in nature.

• It is miscible with water and most of organic solvents.

• It is very powerful oxidizing agent.

• It is also used as germicide for protecting fruits/vegetables against spoilage.

• General formula is C2H4O3.

• It corresponds to acetic acid with additional oxygen atom per molecule.

i.e. CH3COOOH (peracetic acid)

• It is highly unstable at pH 5-5.5. But stable at lower pH of 1.5-2.

• A concentration of 35% to 40% is dangerously explosive.

Mechanism of oxidation with peracetic acid, it gives extra oxygen atom and acetic acid is formed as co-product.

CH3COOH CH3COOH + [O]

Procedure for bleaching with peracetic acid:

1) Peracetic acid being unstable has to be prepared before bleaching being carried out as per above procedure. 2) Bleaching is carried out with

MECHANISM OF PERACETIC ACID

LIQUID AMMONIA MERCERIZATION In this technique the fabric is first passed through drying cylinders to reduce the moisture content of fabric then through a cooling station.

Afterwards it is impregnated with liquid ammonia in a closed chamber and then the fabric is passed through felt calendars in which 90-95% of ammonia is removed.

Advantages over alkali mercerization:Quick processLow shrinkage post washing Superior in the degree of improvement in strength Durability of dimension stabilitySoft handle

LIQUID AMMONIA MERCERIZATION

Rapid changes in technology a dire need to conserve water and energy have forced the textile industry to give up the old conventional processes and try out new methods

All over the world, the environmental regulations are becoming more and more stringent and are forcing the shift of technology towards less polluting or non-polluting areas of technological development.

To go towards the eco friendly and sustainable textile processing, New technology has to be incorporated in the textile processing

CONCLUSION