bio processing of textiles - md. rafsan jany

Department of Textile Engineering

BIO-PROCESSING OF TEXTILES (Bio-polishing & Enzyme washing)

A Dissertation submitted to the Department of Textile Engineering in partial fulfillment of

the credit requirement for achieving the Bachelor Degree in Textile Engineering by Southeast University

2007200400024 Md. Rafsan Jany

Supervisor: Dr. Shah Mohammad Fatah-ur-Rahman Associate Professor September, 2011.

By

Department of Textile Engineering


A Dissertation submitted to the Department of Textile Engineering in partial

fulfillment of the credit requirement for achieving the Bachelor Degree in Textile Engineering by Southeast University

2007200400024 Md. Rafsan Jany

Supervisor: Dr. Shah Mohammad Fatah-ur-Rahman

Associate Professor September, 2011.

By

TO MY PARENTS……………

In The Name of Almighty Allah

Table of Contents Acknowledgement .............................................................. ……………………………………… 1-i Abstract ........................................................................................................................................ 1-ii Objectives ..................................................................................................................................... 1-iii Limitation ..................................................................................................................................... 1-iii Methodology................................................................................................................................. 1-iv

1 Introduction ........................................................................................................................... 1

2 Enzymes .................................................................................................................... ……… 2

3 The history of enzymes ......................................................................................................... . 3

3.1 The history of enzymes in Textile………………………………………………………... 4

4 Properties of the enzymes……………………………………………………………………... 5

5 General Characteristics of Enzymes……………………………………………………………. 6

6 Role of Bio-technology in Textile Processing………………………………………………….. 7

7 Role of Enzymes in Textile Processing………………………………………………………… 7

8 Mechanism of enzyme action…………………………………………………………………... 8

8.1 Model for Enzyme Action are Prepared Based on some Important Properties of Enzymes. 8

8.2 Model for Enzyme Action………………………………………………………………… 8

8.2.1 Lock and key model for enzyme action……………………………………………… 8

8.2.2 Induced fit model for enzyme action………………………………………………….. 9

8.3 How do enzymes work?........................................................................................................ 10

9 Factors affecting efficiency of enzymes………………………………………………………… 10

9.1 Temperature………………………………………………………………………………… 10

9.2 pH…………………………………………………………………………………………… 11

9.3 Concentration of Enzymes………………………………………………………………….. 11

9.4 Concentration of substrate………………………………………………………………….. 11

9.5 Concentration of products………………………………………………………………….. 12

9.6 Radiations…………………………………………………………………………………... 12

10 Classification of Enzymes…………………………………………………………………….. 12

11 Various enzyme used in textile processing……………………………………………………. 13

12 Enzymes for cellulosic textiles………………………………………………………………… 13

12.1 Amalyses……………………………………………………………………………………. 13

12.1.1 Thermo stable amylases……………………………………………………………….. 14

12.1.2 Conventional amylases………………………………………………………………… 14

12.1.3 Low temperature amylases…………………………………………………………….. 14

12.2 Cellulases…………………………………………………………………………………… 14

12.2.1 Acid Cellulases………………………………………………………………………… 14

12.2.2 Neutral Cellulases……………………………………………………………………… 15

12.2.3 Action of Cellulase…………………………………………………………………….. 15

12.3 Pectinases…………………………………………………………………………………… 15 12.4 Proteases……………………………………………………………………………………. 15

12.5 Peroxidases…………………………………………………………………………………. 15

12.6 Laccase……………………………………………………………………………………… 16

13 Trends in Bio-processing……………………………………………………………………… 16

13.1 Bio-catalysis………………………………………………………………………………… 16

13.2 Bio-singeing………………………………………………………………………………… 16

13.3 Bio-scouring………………………………………………………………………………… 16

13.3.1 Advantages of bio-scouring……………………………………………………………. 17

Differences between Conventional scouring & Bio-scouring…………………………………… 18

13.3.2 Integrated Bio- desizing and Bio-scouring…………………………………………….. 18

13.4 Bio-bleaching……………………………………………………………………………….. 19

13.5 Peroxide killers……………………………………………………………………………… 19

13.6 Enzymes effect on color…………………………………………………………………….. 21

13.7 Bio-carbonising……………………………………………………………………………… 21

13.8 Bio-polishing………………………………………………………………………………… 21

13.8.1 Bio-polishing of Knit fabric…………………………………………………………….. 22

13.8.2 Process Variables……………………………………………………………………….. 25

13.8.3 Results…………………………………………………………………………………... 25

13.8.4 Discussion………………………………………………………………………………. 30

13.8.5 Advantages of using enzymes for bio-polishing………………………………………… 31

13.8.6 Disadvantages of this finishing technique……………………………………………….. 31

13.8.7 Troubleshooting for bio-finishing……………………………………………………….. 31

13.9 Enzyme Wash (Denim)………………………………………………………………………. 32

13.9.1 Materials and methods…………………………………………………………………… 33

13.9.2 Results and discussions………………………………………………………………….. 35

13.9.3 Discussion……………………………………………………………………………….. 38

13.10 Textile Auxiliaries…………………………………………………………………………. 39

13.11 Enzymatic Decolorization…………………………………………………………………. 39

14 Enzyme Inactivation……………………………………………………………………………. 40

15 Why the industry owner should use Bio-technology in textile processing…………………….. 40

16 Conclusion……………………………………………………………………………………… 41

1-i

Acknowledgement The department of Textile Engineering of Southeast University has given me the field to perform the project with the ‘Bio-processing of Textiles’. I am deeply indebted to my honorable supervising teacher specially Dr. Shah Mohammad Fatah-ur-Rahman, Associate Professor and my entire course teacher of textile department as their rendered them hand for all kind of help to me. I would also like to thank Engr. Md. Faridul Hasan, Executive, Dyeing, Viyellatex Group Ltd. for helping by giving me information about the project. The encouragement as a continued source of inspiration provided by my parents is fully appreciated. Finally I would like to acknowledge that I remain responsible for the inadequacies and errors, which doubtlessly remain.

1-ii

Abstract Now a day’s the whole universe is concern about the hygiene and they are looking for eco-friendly processes everywhere. Textile processing is responsible for polluting the environment at a large degree. Use of Cellulase enzyme for denim washing is a standard eco-friendly technique to achieve desired appearance and washing of denim and also the desired appearance of the knit fabric. Applications of enzymes to replace harsh chemicals and other difficulties for the processing industries have been practiced for decades. I have studied the bio-polishing effect of knit fabric & washing effect of denim fabric with Cellulase enzyme under different condition.

1-iii

Objectives Bio-processing is becoming popular to enable companies to remain competitive and profitable through the many benefits achieved by this concept. The main objective of this project is to combine in a single volume the fundamental and major applications of bio-processing which contributes eco friendly process, saving of cost, saving of water uses, ensures the quality, so on by using bio-techniques. To know the effect of bio-polishing on knit fabric/garment. To know the effect of enzyme washing on denim fabric/garment. To find out the washing technique by which faded/old looks effect is created in the

garments.

Limitation IItt iiss bbaasseedd oonn kknniitt ffaabbrriicc.. AAllll tthhee eexxppeerriimmeenntt hhaadd ddoonnee bbyy cceelllluullaassee eennzzyymmee.. FFooccuusseedd oonn bbiioo--ppoolliisshhiinngg && eennzzyyllee wwaasshh oonnllyy..

1-iv

Visited to different washing Industries and knit dyeing

industries

Observed Different processes of bio-polishing &enzyme washing

(cellulase enzyme)

Observed the effect of enzyme on fabric and garments.

Group discussion done

Selected the suitable Process and Recipe of Enzyme

application on Textile Processing

Methodology

Bio-processing of Textiles

1

1 Introduction Bio-processing can simply be defined as the application of living organisms and their components to industrial products and processes. It is not an industry in itself, but an important technology that will have a large impact on many industrial sectors in the future. Bio-processing is the application of biological organisms, systems or processes to manufacturing industries. Bio-processing firms will rely mainly on inexpensive substrates for biosynthesis, processes that will function at low temperatures, and will consume little energy. In Textile Processing the Enzymatic removal of starch sizes from woven fabrics has been in use for most of this century and the fermentation vat is probably the oldest known dyeing process. What has given Bio-processing a new impetus in the last few years has been the very rapid developments in genetic manipulation techniques which introduces the possibility of 'tailoring' organisms in order to optimize the production of established or novel metabolites of commercial importance and of transferring genetic material from one organism to another. Bio-processing also offers the potential for new industrial processes that require less energy and are based on renewable raw materials. Various applications which entail enzyme and colors broadly included fading of denim and non-denim, bio- scouring, bio-polishing, silk degumming, carbonizing of wool, peroxide removal, washing of reactive dyes, etc. incidentally enzymes were consumed to the tune of about 70%in detergents than in textile industry.


2

2 Enzymes Enzyme is a Greek word ‘Enzymos’ meaning ‘in the cell’ or ‘from the cell’. They are the protein substances made up of more than 250 amino acids. Enzymes are high molecular weight protein secreted by living organisms capable of catalyzing the chemical reactions of biological process. Based on the medium for their preparation, they are classified as bacterial, pancreatic (blood, lever etc) malt (germinated barely) etc. their major functions are fails on hydrolysis, oxidation, reduction coagulation and decomposition. Grouped under the following groups:

Oxidoreductases – Oxidation, reduction reaction. Transferases – Transfer of functional groups. Hydrolases – Hydrolysis reaction. Lyases – Addition to double bond or its reverse Isomerases – Isomerisation Ligases – Formation of bonds with ATP clevages. Hydrolases type of enzyme is mostly used in textiles.

Enzymes are preferred in textiles due to the following reasons:

Accelerate the rate of the reaction. Specific in action. Low temperature operation. Safe and control is easy. Replace harsh chemicals. No pollution. Biologically degradable.


3

3 The history of enzymes

The history of modern enzyme technology really began in 1874 when the Danish chemist Christian Hansen produced the first specimen of rennet by extracting dried calves' stomachs with saline solution. Apparently this was the first enzyme preparation of relatively high purity used for industrial purposes.

This significant event had been preceded by a lengthy evolution. Enzymes have been used by man throughout the ages, either in the form of vegetables rich in enzymes, or in the form of microorganisms used for a variety of purposes, for instance in brewing processes, in baking, and in the production of alcohol. It is generally known that enzymes were already used in the production of cheese since old times.

Even though the action of enzymes has been recognised and enzymes have been used throughout history, it was quite recently that their importance were realised. Enzymatic processes, particularly fermentation, were the focus of numerous studies in the 19th century and many valuable discoveries in this field were made. A particularly important experiment was the isolation of the enzyme complex from malt by Payen and Persoz in 1833. This extract, like malt itself, converts gelatinised starch into sugars, primarily into maltose, and was termed 'diastase'.

Development progressed during the following decades, particularly in the field of fermentation where the achievements by Schwann, Liebig, Pasteur and Kuhne were of the greatest importance. The dispute between Liebig and Pasteur concerning the fermentation process caused much heated debate. Liebig claimed that fermentation resulted from chemical process and that yeast was a nonviable substance continuously in the process of breaking down. Pasteur, on the other hand, argued that fermentation did not occur unless viable organisms were present.

The dispute was finally settled in 1897, after the death of both adversaries, when the Buchner brothers demonstrated that cell free yeast extract could convert glucose into ethanol and carbon dioxide just like viable yeast cells. In other words, the conversion was not ascribable to yeast cells as such, but to their nonviable enzymes.

In 1876, William Kuhne proposed that the name 'enzyme' be used as the new term to denote phenomena previously known as 'unorganised ferments', that is, ferments isolated from the viable organisms in which they were formed. The word itself means 'in yeast' and is derived from the Greek 'en' meaning 'in', and 'zyme' meaning 'yeast' or 'leaven'. In 1894, Dr. Jokichi Takamine filed patent applications for Taka koji from Aspergillus oryzae. This is the fungus used in making sake. In the early 1900’s, John Beard experimented with juices extracted from animal pancreases and the effects on cancer tumors. In 1926, Dr. James B. Sumner determined that enzymes are proteins. From 1932 to 1942, Dr. Francis Pottenger conducted experiments on the effects of cooked foods fed to cats. They were compared to cats fed raw food only. The cats fed the cooked foods developed diseases such as arthritis and diabetes. He concluded the raw foods contained some substance, which was destroyed by cooking, and this substance had nutritional benefit.


4

In 1940, Dr. Edward Howell began investigating the connection of chronic degenerative disease and severe enzyme deficiency. He wrote two books: Enzyme Nutrition and Food Enzymes for Health and Longevity. In the 1930’s and 1940’s, Dr. Max Gerson discovered the importance of organically grown whole foods. He found raw fruits and vegetables were the healthiest and concluded that 80% of all disease could be extinguished by eliminating canned, frozen and processed foods from the diet. In 1963, William Kelley D.D.S. rediscovered the connection between pancreatic enzymes and cancer remission.

3.1 The history of enzymes in Textile Amylase Desizing(1952). Protease Wool (1984). Cellulase Bio-stoning (1987). Catalase Bleach cleanup (1993). Laccase Denim Bleaching (1996). Peroxidase Enzymatic Rinse (1999). Pectate Lyase Bio-scouring (2003).


5

4 Properties of the enzymes

Enzymes are proteins that catalyze or increase the rate of a chemical reaction. They show following properties -

Specificity –

Each enzyme can catalyze the change of either a specific substrate or a specific group of substrate.

The specificity for a substrate can easily be demonstrated.

Optimum Temperature –

Enzymes generally function in a particular range of temperature which usually corresponds to the body temperature of the organism.

Each enzyme shows its peak activity at a specific temperature called the Optimum temperature.

Activity declines both above and below the optimum temperature. Low temperature preserves the enzyme in a temporarily inactive state. High temperature destroys enzyme activity, because proteins are denatured by heat. For this reason, only a few cells can tolerate temperatures above 45 degrees centigrade. Some heat resistant microorganisms living in hot springs at temperatures close to 100

degrees centigrade possess heat resistant enzymes.

Optimum pH –

Each enzyme shows its highest activity at a specific pH. This pH is called Optimum pH. Activity declines both above and below the optimum pH. Most intracellular enzymes function best near neutral pH.


6

5 General Characteristics of Enzymes An enzyme lowers/ reduces the activation energy required to carry out the reaction. Enzymes themselves do not undergo any change, means they remain intact at the end of

reaction. Enzymes are highly specific for their substrates. Enzymes are present in very less amount in body and have specific life span. Activators are the molecules that enhance the enzyme activity. Inhibitors are the molecules that reduce the enzyme activity.

Activity of enzymes depends upon:

Concentration of specific enzymes Concentration of its substrate pH of reaction Temperature of reaction Concentration of salts Presence of activator or inhibitor Time required to carry out the reaction Presence of proteolytic enzymes.


7

6 Role of Bio-technology in Textile Processing The major areas of applications of biotechnology in textile industry are, Improvement of plant varieties used in production of textile fibres and in fibres and in

fibre properties. Improvement of fibres derived from animals and health care of animals Novel fibres from biopolymers and genetically modified microorganisms Replacement of harsh and energy demanding chemical treatments by Environment

friendly routes to textile auxiliaries such as dyestuffs Novel uses for enzymes in textile finishing Development of low energy enzyme based detergents New diagnostic tools for detection for adulteration and quality control of textiles Waste managements

7 Role of Enzymes in Textile Processing Enzymes are large protein molecules made up of long chain amino acids which are produced by living cells in plants, animals and microorganism such as bacteria of fungi. Enzymes are secretions of living organisms, which catalyze biochemical reactions. Enzymes are biocatalysts without which no life in plant or animal kingdom can be sustained. Today enzymes have become an integral part of the textile processing. Though enzyme in desizing application was established decades ago, only in recent years the application has widened with new products introduced. With the increase in awareness and regulation about environment concerns, enzymes are the obvious choice because enzymes are biodegradable and they work under mild conditions saving the precious energy. Enzymes being biocatalysts and very specific are used in small amounts and have a direct consequence of lesser packing material used, the transportation impact is lower. In an overall consideration enzymes are the wonder products. Salient features of enzyme application in textile process are Extremely specific nature of reactions involved, with practically no side effects. Low energy requirements, mild conditions of use, safe to handle, non- corrosive in their

applications. On account of lesser quantities of chemicals used in process as well as ease of

biodegradability of enzymes results in reduced loads on ETP plants. Enzymes under unfavorable conditions of pH or temperatures chemically remain in same

form but their physical configuration may get altered i.e. they get “denatured” and lose their activity. For this reason live steam must never be injected in a bath containing enzymes and any addition of chemicals to the enzymes bath must be done in pre-diluted form.

Compatibility with ionic surfactants is limited and must be checked before use. Nonionic wetting agents with appropriate cloud points must be selected for high working efficiency as well as for uniformity of end results.

High sensitivity to pH, heavy metal contaminations and also to effective temperature range. Intense cautions are required in use.


8

8 Mechanism of enzyme action

Enzymes are complex biochemical catalysts, speeding up a particular reaction to produce an ordered, stable reaction system in which the products of any reaction are made when they are

needed. A specific enzyme controls each reaction in a series of metabolic reactions. Enzymes also control cell metabolism by regulating how and when reactions occur.

They are made up of globular proteins that have complex tertiary or quaternary structure. Enzyme shape is maintained by hydrogen bonds and ionic forces and their function can be affected by changes in temperature and pH.

8.1 Model for Enzyme Action are Prepared Based on some Important Properties of Enzymes.

Each enzyme is specific and catalyzes only one reaction at a time Enzymes combine with their substrates to form temporary enzyme-substrate complex. Enzymes are not altered or used up in the reactions they catalyze, so can be used again

and again. Enzyme catalyzed reactions are sensitive to temperature and pH. Enzyme catalyzed reactions can be slowed down or stopped by inhibitors. Enzymes lower the activation energy of a reaction thus making the reaction to occur very

rapidly with large turnover numbers.

8.2 Model for Enzyme Action There are two models proposed for enzyme action. They are as follows:

8.2.1 Lock and key model for enzyme action

It was proposed by Emil Fischer. Lock and key model states that a substrate fits into the enzyme in a similar way as a key fits into a specific lock. The active site is a particular shape (the lock) into which only one substrate (the key) will fit. The substrate fits the active site because it is a complementary shape and because the chemical charges attract each other (amino acids at active site are charged). The enzyme and substrate combine for an instant to form an enzyme substrate complex. The formation of this complex brings about the desired chemical reaction, converting substrate into products.


9

8.2.2 Induced fit model for enzyme action

It was proposed by Daniel Koshland. This model suggests that the active site in many enzymes is not exactly the same shape as the substrate, but moulds itself around the substrate as the enzyme substrate complex is formed. Before substrate binding the active site of the enzyme is relaxed. When the substrate binds the active site is pulled into correct shape by molecular interactions between the two molecules and enzyme- substrate complex forms. As the products fall away from the active site, the molecule becomes relaxed again

Figure 1-Lock & key model of enzyme specificity

Figure 2-Active site of enzyme blocked by poison molecule

Figure 3-Induced fit model


10

8.3 How do enzymes work?

Enzymes are thought to have an area with a very particular shape. When a molecule of the right chemical for that enzyme comes along it will fit exactly into the shape. The area of particular shape is called the active site of the enzyme, as that is where the reaction takes place. The molecule that the enzyme works on is called the substrate. After the reaction has taken place and the products of the reaction leave the active site leaving it ready for another molecule of the chemical. The active site of an enzyme has such a particular shape that only one kind of molecule will fit it, rather like a particular key fitting a lock. This is why enzymes are specific in their action.

9 Factors affecting efficiency of enzymes

9.1 Temperature Enzymes work at particular temperature. Change in temperature alters their

efficiency. Most of enzymes work at 40-6000C. Above optimum temperature, heat alters the shape of enzyme molecule, changing

the shape of active site. This leads to reduction in their activity.

Figure 4-Working of enzyme


11

9.2 pH Some enzymes work best in alkaline medium, while some work best in acidic

medium for every enzyme there is optimum pH where its activity is highest.

9.3 Concentration of Enzymes Increase in concentration of enzymes increases the reaction rate.

9.4 Concentration of substrate Increase in concentration of substrate increases the reaction rate till certain point.


12

9.5 Concentration of products Accumulation of products decreases the enzyme activity.

9.6 Radiations Exposure to UV rays, X-rays reduces their reactivity.

10 Classification of Enzymes Oxido Reductases:

These enzymes catalyze oxidation-reduction reactions involving transfer of atom or electrons. Transferases:

These enzymes transfer C, N, P or S containing groups from one substrate to another. Hydrolases:

These enzymes catalyze cleavage reaction by hydrolysis. Lyases:

They non-hydraulically remove group from the substrate with formation of double bond or add new groups across double bond to convert it into single bond. Isomerases:

These enzymes catalyze intermolecular rearrangements to form an isomer. (Isomer –Same molecular formation but different structural formula) Ligases:

These split C-C, C-O, C-N, C-S or C-halogen bonds without hydrolysis or oxidation.


13

11 Various enzyme used in textile processing

12 Enzymes for cellulosic textiles

12.1 Amalyses Amylases are hydrolase class of enzymes, which hydrolyses 1-4 α glucosidic linkage of amylase and amylopectin of starch to convert them into soluble dextrins. Among the different classes of commercially available amylases, some important industrial enzymes for textile and their sources are given below.

Animal Enzymes Enzyme Source Catalase Liver Lipase Pancreas

Protease Pancreas Bacterial Enzyme

-amylase Bacillus Protease Bacillus

Plant Enzyme Protease Carica papaya

Type Action

Amylases To decomposes starches in sizing preparation

Catalases Act on hydrogen-peroxide to decompose it into water & oxygen

Proteases When combines, act on proteins, pectins & natural waxes to effect scouring

Laccases Decompose indigo molecules for wash-down effect on denim

Cellulases

Break down cellulosic chain to remove protruding fibres by degradation & wash-down

effect by surface etching on denim etc.


14

FUNGAL ENZYMES

α-amylase Aspergillus Catalase Aspergillus

Cellulase Trichoderma

Trameters Hirsuta

Laccase Phlebia radiate

Lipase Rhizopus Aspergillus

Pectinase Monilinia Fructigena

Protease Aspergillus The following types find major application in textiles.

12.1.1 Thermo stable amylases Amylases which catalyse starch hydrolysis in the temperature range of 70-1100C and at pH 6.0-6.8.

12.1.2 Conventional amylases Amylases which catalyse starch hydrolysis in the temperature range of 50-700C and at pH 6.0-6.8.

12.1.3 Low temperature amylases Majority of fungal amylases which catalyze starch and hydrolysis in the temperature range of 30-700C and at pH 6.0-6.8.

12.2 Cellulases Cellulases are hydrolase class of enzymes which cleavage 1-4β glucosidic linkage of cellobiose chain or cellulose. The commercially available cellulases are a mixture of enzymes viz., Endogluconases, Exogluconases and Cellobiases, Endogluconases are subclass of celluase enzymes which randomly attack the cellulose enzymes and hyudrolyze the 1-4 β glucosidic linkage of cellobiose chain. Exoglucanases of cello-biohydrolases are again subclass of cellulose enzyme which hydrolyses 1-4 β glucosidic linkage of cellulose to release cellotiose from the cellulose chain and Cellobiases are enzymes whichhydrolyse cellobiose into soluble glucose units. All these three enzymes act synergistically on cellulose to hydrolse them. Among the different classes of commercially available cellulases, following types find major application in textiles.

12.2.1 Acid Cellulases Acid cellulases are class of enzymes that act at pH 3.8-5.8 (-optimum 4.5-6) and in the tempereature range of 30-600C. The low temperature range is of 30-600C and conventional acid cellulases act in the temperature range of 45-600C.


15

12.2.2 Neutral Cellulases Cellulase enzymes which actr at pH 6.0-7.0 and in the temperature range of 40-550C are termed as neutral Cellulases.

12.2.3 Action of Cellulase Enzymes are large molecular complex and can’t penetrate interior of the fabric. Hence enzyme action takes place preferentially on the surface. Where cleavage of cellulose chain occurs, Microfibrils which are loose fibres break off under the influence of bio-catalytic degradation and results in better mechanism or modify the surface of the fabric. Enzymes contain activity centre in three dimensional structure form namely fissures, holes, pockets, cavities, hollows. These enzymes first of all form an enzyme substance complex on the surface of the cellulose. Bio-reaction then takes place in the above mentioned substrate mentioned enzyme substrate complex. Finally, the complex disintegrates with the release of the reaction products and the original enzymes which are once again available.

12.3 Pectinases Pectinases are a mixture of enzymes, which along with other such as cellulose, are widely used in the fruit juice industry. Enzymes in this pectinase group include polygalacturonases, pectin methyl esterase and pectin lyases. These pectinase enzymes act in defferent ways on the pecans, which are found in the primary cell walls of cotton and jute. Pectins are large polysaccharide molecules, made up of chains of galacturonic acid residues.

12.4 Proteases Proteases are Hydlolase class of enzymes, classified based on the source from which it is extracted, optimum temperature of activity. Proteases precisely act on peptide bonds formed by specific amino acids to hydrolyze them. Commercial proteases are available, which can work in different range of pH and temperature. Trypsin (pancreatic), Papain based and alkaline proteases find industrial applications in textiles.

12.5 Peroxidases Peroxidases or Catalases are Oxidoreductase class of enzymes. The perosidase enzyme catalyse the decomposition of hydrogen peroxide in to water and molecular oxygen as illustrate. 2 H2O2→2 H2O + O2 Catalase is a heam-contaioning enzyme. Thus, in addition to the protein part of the molecule the enzyme contains a non-protein part, which is a derivative of heam and includes the metal iron.

Figure 5-Cellulase enzyme


16

Peroxidases effectively degrade the hydrogen peroxide at varied pH between 3 to 9 and in the temperature range 30 -800C.

12.6 Laccase Laccases are Oxidoreductase class of enzymes, belonging to bluoxidase- copper metalloenzymes. Lassases are generally active at pH 3-5 and in the optimal temperature range of 30-500C. They oxidize using molecular oxygen as electron acceptor from the substrate. Their special property of oxidation of indigo pigments is made use of in textile industries.

13 Trends in Bio-processing

13.1 Bio-catalysis Owing to the specific nature, enzymes have become an important class of bio-chemicals in textile processing. Being bio-catalysts, enzymes were not consumed in the reaction. They were also used in the processing from a standing bath. Illustrating a schematic diagram for working of an enzyme, he indicated the active and secondary sites and how the enzyme was larger than the substrate as it attached itself to cellulose forming a complex in which the concentration of the reactants increased thousands times due to which the reaction proceeded. The substrate was broken into degradation products making the enzyme available to attach itself again to another substrate and the cycle was repeated and thereby the enzyme became a biocatalyst.

13.2 Bio-singeing This mode of finishing has been specifically developed to achieve clearer pile on terry towel goods. A treatment with an enzyme, which is a powerful cellulase composition, gives clearer look to the pile, improves absorbency and softness. Earlier, desizing was carried out by steeping the fabric with mineral acid, which affected the cellulose as well as the colour. Use of enzymes here led to reaction with the starch only and thus they assumed considerable significance. Explaining the action of enzymes, the food consumed by human body was digested due to secretion of the enzyme. At the enzyme-substrate complex level, the concentration of the reactants became large and accelerated the reaction while reducing the activation energy barrier. Thus, the reaction which took place at higher temperature and severe conditions could be carried out at relatively lower temperatures and milder conditions.

13.3 Bio-scouring Bio scouring did not involve any colour, yet after scouring the fabric was dyed with colours. Cotton could be treated with bio-scouring enzyme although the techno-economical parameters were not conductive. But, it had a bright future due to rigorous effluent treatment since disposal of both caustic soda and soda ash was causing environmental concern. The enzymes helped


17

removal of waxes, pectins, sizes and other impurities on the surface of the fabric. Combination of pectinase and lipase gave best results, but cost of the latter was a deterrent. Advantages of bio-scouring were lower BOD, COD, TDS, and the alkaline media of water, extent of cotton weight loss, which was a boon to the knitting industry, lower alteration of cotton morphology i.e. less damage since it was specific to pectin and waxes and not cellulose besides increased softness. The lone disadvantage was that the cotton motes were not removed, which warranted peroxide bleaching. Traditionally, cotton scouring has required the use of harsh alkaline chemicals (caustic), extreme temperatures water. Expenses include not only the cost of the caustic and energy, but also the cost of treating wastewater to caustic and by-products. Today, textile producers have a new, effective alternative to chemical scouring with the advent of the Cottonas novel enzyme not only cleans better than chemical scouring. But also greatly reduces the need for extensive and energy consumption. The Cottonase T enzyme is a versatile, economically viable and environmentally friendly chemical scouring in cotton preparation. Noncellulosic impurities, such as fats, waxes, proteins, pectins, natural and water-soluble compounds, are found to a large extent in the primary wall and to a lesser extent in the secondary 3) and strongly limit the water absorbency and whiteness of the cotton fiber. Quantity and composition varies v present serious problems as they are basically undyeable. The bio scouring process is built on – Protease Pectinase Lipase enzymes act on proteins & natural waxes to effect scouring of cotton.

13.3.1 Advantages of bio scouring Milder conditions of processing, low consumption of utilities, yet excellent absorbency in

goods. No oxy-cellulose formation and less strength loss because of absence of heavy alkali in

bath. Uniform removal of waxes results in better levelness in dyeing. Highly suitable for scouring of blends containing fibres like silk, wool, viscose,

modal, lyocell, lycra etc. Low TDS in discharge. Fabric is softer and fluffier than conventional scouring. Ideal for terry towel/ knitted

goods.


18

Differences between Conventional scouring & Bio-scouring

Conventional scouring Bio-scouring

Process carried at high temperature and pressure for 4-6 hours

Process carried at ambient temperature and pressure

Process is energy intensive Low energy process

Residual alkali in effluent is high Residual alkali in effluent is negligible

Water consumption in the process is high Water consumption in the process is low

Fabric quality attributes:

Parameter Conventional scouring Bio-scouring

Fabric weight loss (%) 13 12

Water absorbency(seconds) Instantaneous 3

Whiteness index 70 67

Fluidity 2.2 6.8*

2.3 2.9*

Color strength(K/S) 10 11

Strength retention (%) 77.4 82.5

*Scoured & bleached. Source- Central Institute for Research on Cotton Technology, India.

13.3.2 Integrated Bio- desizing and Bio-scouring The integrated Bio-desizing and Bio-scouring system uses an empirically developed enzyme formulation, based on amylase, pectinase, protease and lipase that act synergistically, resulting in desizing and scouring of cotton goods, under mild conditions.


19

Material Enzyme based speciality

Wetting agent Remarks

Yarn Ecoscour Unopol AW Excellent absorbency in 55-60 minutes

Knits Ecoscour Unozin SD Specific wetting agent

for Mineral oil contaminants.

Desized woven Ecoscour Unozin SD Applicable by pad or

Exhaust methods.

Grey woven Ecoscour DS Unozin SD Single stage desizing

and scouring by pad or exhaust

13.4 Bio-bleaching It was applicable for all kinds of colours and a single enzyme could be used in the textile industry. Bio-bleaching had been adapted for denim. Indigo specific lipases were used to bleach indigo. Earlier denim was bleached with chlorine to get lighter denim or wash down effect. Lipase combination was used successfully and if this could be extended to other colours, this would become an important enzyme in future. The advantages were environment friendly application, non AOX generation and cellulose was not affected. A bio-bleaching or lipase treatment on denim gave an authentic wash resulting in an excellent look, which was better than a neutral wash and a grey cast, which was used in bleaching. Amylase and lipase were used for desizing and cellulase for aberration. Lactase was introduced for bleaching of indigo.

13.5 Peroxide killers It ensured shade quality particularly with reactive dyes, reduced the complexity of treatment after peroxide bleaching and conserved water. In case of reactive dyeing, after bleaching it was vital that the peroxide residues must be cleared out of the system and as such there were no fool proof ways of such clearance, which entailed several rinsing operations or reduction treatments. Empirically, it was difficult to know how much quantity of reducing agent was required to react with the peroxide left in the bath. In the event either of them happened to be excess, it might affect the dyeing. Therefore, after bleaching, the bath should be neutralized with peroxide killers like peroxidase or catalase followed dyeing with reactive dyes. They did not affect reactive dyes and only react with the peroxide. These catalysts were fastest acting type as 1 molecule of catalyst destroyed 5 million molecules of peroxide or 700 times its own weight of peroxide. Catalase for Bleach Clean-up – Saving water and energy Fabrics are often bleached with hydrogen peroxide prior to dyeing and finishing. Residual hydrogen peroxide must be removed to obtain the most efficient dyeing. Repeated water washes


20

or chemical reducing agents have traditionally been used, and now it is common practice to apply catalase enzymes which decompose hydrogen peroxide to oxygen and water. Significant process savings are possible because the treatment is fast, mild, and dyeing can be carried out in the same liquor and equipment as the catalase treatment. Efficiency of H2O2 removal

Conventional process Enzymatic process

Process Residual peroxide, ppm Process Residual

peroxide, ppm

After bleaching 100 After bleaching 100

After the 1st hot rinse 60 Catalase, 5 min 10

After the 2nd hot rinse 10 Catalase, 10 min 2

After the 1st cold rinse 2 Catalase, 15 min 0.5

Before dyeing 0.5 Catalase, 20 min 0

Cost saving:

*(1000 kg of fabric, liquid ratio 10:1.Cost indication is based on China market) Source- Novozymes,China.

Time Water Steam Power Catalase Acid Total cost, $

Conventional process

230 min

50 tons 9 m3 92

KWH

Cost, $ 18.8 135 9.2 163

Enzymatic Process

100 min

20 tons 3 m3 44

KWH 0.7 kg 5 kg

Cost, $ 7.5 45 4.4 7 3.8 67.7

Savings, $ 95.3


21

13.6 Enzymes effect on color Hydrolases and oxireductases constituted important class of enzymes which dealt with colour in textile application. Speaking about how the enzymes affected these applications one said that when looked at fading, especially of denim, one came across the three classes of cellulase viz. acid, neutral and engineering. The affect of cellulase on denim and the wash down effect was attributed to the yarn, which was ring dyed i.e. yarn dyed with indigo was present only on the outer ring of the denim. Due to affect of enzyme and physical aberration of cellulose, the exposed areas became white as well as indigo dyed. If it was non denim, it was ring dyed non denim containing vat, sulphur or pigments. This kind of effect on denim was called salt and pepper effect. The more contrast, better was the denim wash. Some of the denims had blue or greyer cast because they were woven with one up or two down and one of the yarn was coloured while the other wasn’t. thus, the effect was created with the combination of the hydrolysis of 1-4 glucose linkage in cellulose and the abrasion e.g. turbulence of friction of metal to metal or fiber to fiber led to denim appearance. Combination of enzyme, sand blasting and bleach evolved a fashion recently. Sand blasting was enzyme treatments which subject the denim fabric to sand at high pressure with consequent exposure of white area while blowing off surface colour followed by a treatment of the fabric again with enzyme, leading to a salt and pepper effect and bleached to reduce the colour value. Furthermore, after sand blasting, treatment with enzyme followed by over dyeing of the abraded areas produced typical effects on denim.

13.7 Bio-carbonising Polyester / cellulosic blends after dyeing and/ or printing are occasionally treated with strong solution of sulphuric acid to dissolve cellulosic component. The resultant goods are soft and have a peculiar fluffy feel. This process is risky due to highly corrosive acid that is also difficult to treat in an ET plant. The process developed at UNO, has none of the above drawbacks. It offers a safe and eco-friendly to the obnoxious practice of using sulphuric acid. The goods are treated with cellulose enzyme based formulation to achieve dissolution of cellulosic fibers.

13.8 Bio-polishing Bio-finishing also called bio-polishing, is a finishing process applied to cellulose textiles that produces permanent effects by the use of enzymes. Bio-finishing removes protruding fibres and slubs from fabrics, significantly reduces pilling, softens fabric hand and provides a smooth fabric appearance, especially for knitwear and as a pretreatment for printing. Second rate articles can obtain the high value eye appeal of first rate ones. In denim processing, bio-finishing can reduce or eliminate abrasive stones and the aggressive chlorine chemistry, achieving the desired “worn” looks. Bio-finishing is not only useful for cotton but also for regenerated cellulose fabrics, especially for lyocell and microfiber articles. By incorporating enzymes into detergents to


22

remove protruding surface fibres, improved colour retention is achieved after multiple launderings. The disadvantages of bio-polishing are the formation of fibre dust, which has to be removed thoroughly, the reproducibility of the effect (which is dependent upon many parameters) and in the worst case, loss of tear strength. Enzymes are high molecular weight proteins produced by living organisms to catalyse the chemical reactions essential for the organism’s survival. They have complex three-dimensional structures composed of long chains of amino acids with molecular weights ranging from 10,000 to about 150,000 and occasionally to more than 10, 00,000. These naturally occurring molecules provide a high degree of catalytic specificity unmatched by man-made catalysts. The enzyme and substrate form a ‘lock and key’ complex that requires the enzyme to have a specific molecular alignment in order to act as a catalyst. The lock and key theory of Emil Fischer was broadened by Koshland Jr to the induced-fit theory of the enzyme-substrate-complex. Chemical reactions catalysed by enzymes can typically be carried out, as is most usual in nature, under mild aqueous conditions without the need for high temperatures, extreme pH values or chemical solvents. Knitted goods treated with enzymes are free from surface hairiness and neps with much improved handle and flexibility. The fabric surface becomes smoother and more lustrous. There is also a lower tendency to further pilling possibly due to the fact that there are less protruding fibre ends from the yarns after the enzyme application.

13.8.1 Bio-polishing of Knit fabric

Stage-1: One bath Scouring and Peroxide bleaching Recipe: Anti-foaming 0.07gm/l Rucozen WBX (Detergent) 0.5gm/l Stabilizer SOF 0.5gm/l Primasol jet (Anti-creasing) 1.5gm/l Securon 540 (Sequestering) 1gm/l Caustic 2gm/l H2O2 2.5gm/l pH 10-11 Temperature 1050C Time 50min

Stage-2: Bio-polishing

Recipe: BP Nano 0.9gm/l Acetic acid 1gm/l T-100 (Peroxide killer) 0.08gm/l Securon 540 0.25gm/l pH 4.5-5 Temperature 550C-600C Time 40-60min


23

Fresh water andfabric Load at 450C

Temperature raise to600C

Detergent & PeroxideStabilizer (Inject)

Run for 5 min

Inject Caustic and run5 min

Raise temperature to700C

H2O2 inject and run 5min


Run for 30 min

Lower thetemperature to 800C

Bath drain

BP Nano & Aceticacid

Securon 540 &Peroxide killer inject


Run for 60 min

Rinsing and unloadthe fabric.

Process Flow Chart


24

Well scoured and bleached sample

Dye addition

Salt addition ( 2 instalment )

Soda ash addition ( 2 instalment )

Dyeing

Hot wash

Hot wash

Soaping ( at boil )

Hot wash

Cold wash

Bio-polishing

Cold wash

Drying

Well scoured & bleached sample

Bio-polishing

Cold Wash

Drying

Dye addition

Salt addition

Addition of Soda ash

Hot wash

Hot wash

Soaping

Hot wash

Cold wash

Drying

Process sequence Dyeing followed by bio-polishing Bio-polishing before dyeing


25

13.8.2 Process Variables Concentration Temperature pH Time M : L Ratio Mechanical Agitation

To achieve optimum bio-polishing, the process variables have been varied as mentioned below. Concentration of enzyme: 0.5%, 1%, 2%, 2.5%, 3% & 4%. Temperature: 400C, 45 0C, 500C, 550C & 600C. pH: 3-4, 4-5 & 5-6. M: L: 1:5, 1:10, 1:15 & 1:20. Mechanical Agitation: Vigorous Stirring, Medium Stirring & Without Stirring.

13.8.3 Results

13.8.3.1 Factors affecting bio-polishing Bio-polishing is affected by many factors. Major ones are Enzyme, Type of Fabric and Process Variables. The predominant process variables which control the bio-polishing are Temperature, pH, Duration of treatment, Material to liquor ratio, Enzyme concentration and Mechanical agitation. To find the effect of above mentioned factors we have carried out the bio-polishing by following ways. 1) Keeping M: L ratio, pH and temperature constant and varying the concentration of enzyme. 2) Keeping temperature and pH constant and varying the material to liquor ratio. 3) Keeping M : L ratio constant and varying the temperature. 4) Keeping temp. and M : L Ratio constant and varying the pH of solution. 5) Keeping all these parameters constant and varying the duration of treatment

13.8.3.1.1 Effect of Concentration Concentration of enzyme is a major factor which affects the performance of the bio-polishing of the knitted fabric. There are different types of enzymes available in the market. Each enzyme has an optimum concentration, pH and temperature range.


26

In our study, we have used Cellusoft-SO, which is an acid stable cellulase. By varying the concentration of cellulase and keeping the other parameters, such as pH, temperature, time and material to liquor ratio constant, we have observed that the best bio-polishing can be obtained at the following conditions : M: L 1:8 pH 4.5-5 Temperature 55-600C Time 40-60min To observe the effects of conc. of Enzyme on bio-polishing, we have treated knitted fabric with various concentrations of Cellusoft-SO. 0.5%, 1%, 1.5%, 2%, 2.5%, 3% and 3.5%. Results obtained are depicted in Table 1.

Effects of concentration of enzyme on bio-polishing Source- Textile & Engineering Institute, Ichalkaranji. From this table, it can be concluded that as the concentration of cellulase increases from 0.5% to 2.0%, weight loss increases significantly. Optimum percentage weight loss is obtained at 3% conc. Increase in conc. of enzyme causes an increase in strength loss. Fabric thickness is reduced with increase in conc. of enzyme. Hence 3% conc. of enzyme is the optimum dose.

13.8.3.1.2 Effects of Temperature Temperature affects the performance of cellulase. Each enzyme has an optimum temperature range where enzyme activity is maximum. Hence it is essential to determine the optimal temperature. Increase in temperature decreases the enzyme activity rapidly and the enzyme action comes to almost zero and the enzymes are permanently deactivated at 700C. Low temperature shows reduction in reaction speed but does not deactivate the enzyme. It is therefore possible to use a lower temperature by a longer cycle. The activity of Cellusoft-SO at 400C is only 50%. It is also observed that every 100C rise in temperature doubles the activity of enzyme, as long as it is not deactivated.

Properties Result

Concentration of Enzyme 0.5% 1% 1.5% 2% 2.5% 3% 3.5%

Weight loss (%) 0.36 0.77 0.88 1.46 2.09 2.12 2.07 Abrasion (mm) 0.04 0.06 0.07 0.08 0.08 0.09 0.09 Wash fastness 4-5 4-5 4-5 4-5 4-5 4-5 4-5 Pilling rating 3 3 4 4 4 4 4


27

To observe the effects of temp. on bio-polishing, we have treated knitted fabric with the following recipe. Results obtained are depicted in Table 2. M: L 1:8 pH 4.5-5 Concentration 3% Time 40-60min

Effects of Temperature of enzyme on bio-polishing Source- Textile & Engineering Institute, Ichalkaranji. The optimum result is obtained at 550C temperature.

13.8.3.1.3 Effects of pH pH is also a critical factor affecting the efficiency of bio-polishing. A particular type of cellulase is most effective and can be operated at a certain specific pH range. To observe the effects of pH on bio-polishing, we have treated knitted fabric with 3% Cellusoft-SO at various pH viz. 3-4, 4-5, 5-6, 6-7 & 7-8. Results obtained are depicted in Table 3.

Effects of pH of enzyme on bio-polishing Source- Textile & Engineering Institute, Ichalkaranji. We have observed that the activity of enzyme is maximum at pH 5 – 5.5. But optimum bio-polishing effect is obtained at pH 4-5.

Properties Result

Temperature 400C 450C 500C 550C

Weight loss (%) 0.75 1.03 1.45 2.56 Abrasion (mm) 0.04 0.06 0.07 0.08

Wash fastness 4-5 4-5 4-5 4-5 Pilling rating 3 4 4 4

Properties

Result

pH

3-4 4-5 5-6 6-7 7-8

Weight loss (%) 0.47 1.21 1.1 0.93 0.86

Abrasion (mm) 0.03 0.08 0.06 0.05 0.04

Wash fastness 3 3 4 3 3

Pilling rating 3 4 4 4 4


28

13.8.3.1.4 Effects of M: L Ratio M: L Ratio has a substantial effect on bio-polishing. As the liquor ratio increases the bath conc. of cellulase decreases, and the fabric weight loss decreases. The dilution affects substantially enzymatic activity. To observe the effects of M: L ratio on bio-polishing, we have treated knitted fabric with 3% BP Nano at various M: L ratios viz. 1:5, 1:10, 1:15 & 1:20. Recipe: Concentration 3% pH 4-5 Temperature 550C Time 50min Results obtained are depicted in Table 4. From this table, it is found that as the liquor ratio increases the pilling rating of treatment sample decreases. At the low M: L Ratio, the fabric show very low pilling and at higher M: L Ratio, pilling tendency of fabric is more. Thus, pilling rating goes on increasing with increases in liquor ratio.

Effects of M: L Ratio of enzyme on bio-polishing Source- Textile & Engineering Institute, Ichalkaranji. The best result is obtained at 1: 10 M : L Ratio.

13.8.3.1.5 Effects of duration To observe the effects of duration of enzyme treatment on bio-polishing, we have treated knitted fabric with 3% Cellusoft-SO for various durations viz. 30 min., 40 min., 50 min. & 60 min. Concentration 3% pH 4-5 Temperature 550C M:L 1:10

Properties Result

M: L Ratio 1:5 1:10 1:15 1:20

Weight loss (%) 1.06 1.12 0.62 0.51 Abrasion (mm) 0.03 0.04 0.06 0.06

Wash fastness 4-5 4-5 4 4 Pilling rating 4 4 3 3


29

Results obtained are depicted in Table 5.

Effects of duration of enzyme on bio-polishing Source- Textile & Engineering Institute, Ichalkaranji. The best result is obtained at 50 min treatment time.

13.8.3.1.6 Effects of Enzyme treatment on Dyeing property To observe the effects of enzyme treatment on dyeing property, bio-polishing of cotton knitted fabric has been carried out before dyeing as well as after dyeing. Concentration 3% pH 4-5 Temperature 550C M:L 1:10 Time 50min The results obtained are tabulated in Table 6.

Effects of Enzyme treatment on dyeing property (3% shade) Source- Textile & Engineering Institute, Ichalkaranji

Properties

Result

Time(min) 30 40 50 60

Weight loss (%) 0.72 1.01 1.42 2.48 Abrasion (mm) 0.04 0.06 0.07 0.07 Wash fastness 4-5 4-5 4-5 4-5

Pilling rating 3 4 4 4

Properties

Results Enzymes treatment after dyeing Enzyme treatment before dyeing

Concentration of Enzyme 1% 2% 3% 1% 2% 3%

Weight loss (%) 0.77 1.23 1.89 0.79 1.25 1.93 Abrasion (mm) 0.04 0.07 0.08 0.05 0.06 0.09 Wash fastness 4 4-5 4-5 2-3 3 3-4 Pilling rating 3 4 4 3 4 4 K/S Values 9.6 8.9 8.1 9.9 9.9 9.9


30

From the above table, it is seen that the properties of pre-dyed enzyme treated sample have been compared with the properties of pre-enzyme treated dyed sample. Dyeing with reactive dyes after enzyme treatment results in somewhat deeper shade. It is due to the surface modification of the knitted fabric before dyeing. This fabric shows poor wash fastness and rubbing fastness than the pre-dyed enzyme treated sample. The pre-enzyme treatment does not make any difference in softness and surface modification as compare to pre-dyed enzyme treated sample The best result is obtained at 50 min treatment time.

13.8.3.1.7 One bath Bio-polishing and dyeing Enzymatic cellulose degradation is also possible during reactive dyeing. Here the dyeing process as well as bio-polishing will be affected. Number of washes, time, cost and energy can be saved by this one bath method. However, it should be noted that there is some reduction in color yield of reactive dyeing. This is because reactive dyeing is carried out in acidic pH during bio-polishing. But precaution is taken during addition of soda-ash as reactive dyes require alkaline condition for its fixation. The fabric is made neutral before adding soda-ash. It is found that neutral stable enzymes are more suitable in this type of one bath treatment. Recipe:

Conventional Method One Bath Method Conc. of Enzyme: 3% Conc. of Enzyme: 3%

M: L Ratio: 1:10 M: L Ratio: 1:10 Temp. : 55 Temp. : 55

Time: 50 mins. Time: 2.5 – 3 hrs. pH: 4-5

13.8.4 Discussion The best result is obtained at 3% concentration of enzyme. 1:10 M: L ratio gives the best result. At pH range of 4-5, enzyme shows maximum activity. At 550C temperature, enzyme activity is maximum. Mechanical agitation supports enzyme activity. Depth of shade increases when enzyme treatment is given before dyeing and the depth

decreases when enzyme treatment is given after dyeing. Pilling tendency decreases with application of enzyme. One bath application saves energy, time & cost. But the bio-polishing effect is not as

good as the two bath method. Wash fastness of the enzyme treated sample before dyeing is very poor. Wash fastness of the enzyme treated sample after dyeing is good. Wash fastness of one bath enzyme treated sample is moderate.


31

13.8.5 Advantages of using enzymes for bio-polishing Hairiness fluffs and pills are removed. Material sticking (the burr effect) is prevented. Improved handle Achievement of surface smoothness and a clear structural appearance. Improved luster. Material texture relaxation Increased flexibility and therefore a soft handle even with over end products and

mercerized fabric. Improved sew ability. Fast to washing, low pilling tendency, no napping in use, or during care operation. Stone wash effect without pumice stone and dyestuff destroying chemicals. Poor quality, uneven, napped, knoppy material surface (i.e.) typical second quality goods

are converted into elegant, lustrous, soft, top quality with a fine, high quality surface appearance.

13.8.6 Disadvantages of this finishing technique

Loss in weight Loss in strength

Cellulases have been used on a large scale for years in medicine analysis, food chemistry and other industries.

13.8.7 Troubleshooting for bio-finishing As mechanical agitations important to effect the bio-finishing, only selected processes and machines can be used, for example tubular fabric preferably cut to open width and treated in open width washers. In the rope form the loosened fibre particles are filtered out by the fabric and cannot easily be removed. The pad-batch process, jig or package dyeing machines are not effective in bio-finishing. Not all cellulase enzymes give identical results, even with similar fabrics in similar equipment. Cellulases derived from Trichoderma typically are the most aggressive in their action, whereas mono-component endo-glucanases often require the most mechanical action to achieve the desired effects. Slow deactivation of the cellulases during transport and storage can adversely affect the reproducibility of the resulting effects. If cotton is not washed carefully before bio-finishing, secondary fibre compounds as residual biocides can deactivate the cellulases. The same is true for natural or synthetic tannic acids, and resist or fastness improving agents for wool or nylon in cellulose fibre blends. Deactivation of cellulases after the desired effects have been achieved is very important. If the enzyme is not completely removed from the fabric, or is not effectively deactivated, the


32

hydrolysis reaction will continue, although at a slower rate. As very large molecules, cellulases cannot diffuse into the crystalline parts of the cellulose fibres. They react on the fibre surface, so fibre damage takes time. But eventually enough hydrolysis will have taken place to weaken the affected fabrics or garments, leading to customer complaints and returns. Undesirable deactivation may be caused by high temperature and time, for example, caused by transport and storage and also by enzyme poisons such as certain surfactants (especially cationic ones), formaldehyde-containing products or heavy metal ions. An activation effect on cellulases was reported by Nicolai and co-workers. Alkaline pretreatment, low concentrations of selected non-ionic surfactants, polycarboxylic acids and polyvinyl pyrrolidone can enhance the bio-finishing of celluloses. The use of pH buffers during the hydrolysis reaction is strongly recommended, especially when abrading denim fabrics. Cellulase enzymes have very narrow pH ranges of effectiveness and denim fabrics can have significant quantities of residual alkali from the indigo dyeing process. Buffers are required to maintain the appropriate reaction conditions for maximum enzyme effectiveness. Because the effect of processing auxiliaries on cellulase catalysis is difficult to predict, it is important to evaluate any changes in processing formulas carefully by conducting small scale trials before making significant changes in production procedures. Removal of protruding fibers from garment surface using cellulase enzymes is called bio-polishing. These enzymes are proteins and capable of hydrolyzing cellulose (cotton). In bio-polishing they act upon the short fibers protruding from fabric surface and make the fibers weak which are easily removed during washing. This process imparts soft and smooth feel and reduces fuzz or pilling tendency. This process is applicable to garments made of cotton and its blends. Two kinds of cellulases are commercially available, acid cellulases which have activity in acidic medium in pH range of 4.5 – 5.5 and neutral cellulases which have activity in pH range of 5.5-8.0. Both these types are active in the range of 450C to 600C.

13.9 Enzyme Wash (Denim)

Industrial washing is one of the most important applied finishing methods on fabric or apparel. Different washing methods can be applied in case of denim fabrics finishing. To achieve special outlook as well as to change the fashion, responsible washing methods are stone wash, sand wash and bleach wash. Denim produced from the fabric with twill weave including warp yarns dyed with indigo color and undyed or white weft yarns

In recent years, there is an interest in using fully biodegradable enzymes which are environmentally friendly and nontoxic in the modern textile finishing process. A number of mechanical and chemical operations can be replaced by enzymatic treatment, which has been applied to improve fabric quality and comfort.

In the textile industry enzymes are applied mainly to get a cleaner fabric surface with less fuzz, to reduce tendency to pill formation, to smooth the surface combining with traditional softeners.


33

To improve fabric handle and other valuable properties, softeners are widely used in finishing operations.

For buying a textile, nice and appealing handle is very often considered most important criterion. Fabric handle can be influenced by using softener which is analyzed in the research work.

Recently some papers have been published to analyze the change of textile's color after applying in different finishing methods as clients when choosing an item from shop always pay attention to its color.

Fabric specification (ends/inch, picks/inch, surface density, warp & weft linear density), fabric tensile strength, fabric stiffness, seam strength, etc must be treated as important characteristics as those determine wear durability and longevity. However, the effects of enzyme wash on the changes of above mentioned characteristics are clearly evaluated in this paper. The aim of this paper is to determine the effects of enzyme wash on denim apparel characteristics.

13.9.1 Materials and methods The investigation has been carried out with currently popular and fashionable regular denim garments. Basic characteristics of selected unwashed denim garments are mentioned below-

13.9.1.1 Materials selection Denim fabric composition: 100% cotton Indigo dye. Weave: twill 3/1 weave Ends/inch: 50-51 Picks/inch: 41-42 Surface density (gm/m2): 352-353 Warp linear density (Ne): 6-7 Weft linear density (Ne): 11-12 The denim garments have been processed by various types of enzyme washing and finally softening method as mentioned below.


34

13.9.1.1.1 Method of desizing Denim trousers has been subjected to Enzymatic desizing process for removal of size materials which were added in the sizing process to reduce ends breakage rate during weaving the fabric. Here desizing was carried out by using following suitable recipe while maintaining proper time and temperature.

Table1: Recipe of desizing Process parameter Amount

Soda ash 400gm Caustic soda 400gm Temperature 700C

Time 15min After desizing the apparel was washed off for two times

13.9.1.1.2 Method of enzymatic wash By desizing size materials were completely removed from the denim trousers, and after that it was washed by cellulase enzyme with typical industrial recipe as mentioned below: During enzymatic treatment removed indigo dye can be re- deposited on the white or undyed weft yarn of denim fabric which is known as back staining process and it can diminish the outlooks of the trousers. So anti back staining agent was used here to resist back staining. After washing with enzyme, the trousers were washed off for two times.

13.9.1.1.3 Method of softening After sand blasting and enzyme wash, silicon softener was used to make the denim fabric soft and improve handle property, as explained below in table 3.

Table3: Recipe of fabric softening Process parameter Amount Softener(Cationic) 200gm

Wash 2 times Temperature Room temp.

Time 5min After softening the apparel was washed off for two times.

Table 2:Recipe of enzyme wash Process parameter Amount

SL enzyme 400gm Acetic acid 200gm

Anti back staining agent 200gm Temperature 400C

Time 12min


35

13.9.1.1.4 Method of changes evaluation Change of Fabric handle property: Fabric handle property was checked properly before and after enzyme washing by feeling or touch. Change of Fabric Specification: By counting glass ends/inch and picks/inch were calculated from denim fabric of the trousers. GSM cutter was used to calculate the surface density (gram/square meter) of denim fabric by ISO 7211. To determine the warp and weft linear density (count) from denim trousers, Beesleys direct reading balance was used by following ISO 7211/4:1984. Change of fabric Strength: Tensile strength of denim fabric was calculated by the help of fabric strength tester. EN ISO 13935 – 2; 1999Grab method was used for Tensile Strength measurement. Change of fabric Stiffness: Stiffness of denim fabric was measured by fabric stiffness tester. Change of Seam Strength: Seam strength of trouser was measured by seam strength tester. Methods: ISO 13935-2: 19999E ASTM D 1683: 2007

13.9.2 Results and discussions

13.9.2.1 Changes of Fabric Handle after washing Enzyme washes Portions of denim garments:

Before wash: Harsh feeling and rough surface. After wash: More soft and smooth surface.

Figure 7- Raw Sample Figure 6-After wash Sample


36

13.9.2.2 Changes of fabric specification after washing

Table 4: Effects of enzymatic wash on fabric specifications

Item No. of Observation Before wash After wash Difference % of

Difference Average % of

Change

EPI

1 41 44 +3 +7.32

+6.88

2 40 43 +3 +7.50

3 39 42 +3 +7.69

4 42 44 +2 +4.76

5 42 45 +3 +7.14

PPI

1 38 42 +4 +10.53

+7.33

2 39 41 +2 +5.13

3 40 42 +2 +5

4 38 41 +3 +7.89

5 37 40 +3 +8.11

Warp count (Ne)

1 7 10 +3 +42.86

+34.52

2 8 10 +2 +25

3 7 9 +2 +28.57

4 7 10 +3 +42.86

5 6 8 +2 +33.34

Weft count (Ne)

1 9 10 +1 +11.12

+13.39

2 8 9 +1 +12.50

3 9 11 +2 +22.23

4 10 11 +1 +10

5 9 10 +1 +11.12

Surface density

(gm/m2)

1 337 335 -2 -0.59

-0.825

2 336 333 -3 -0.89

3 338 335 -3 -0.88

4 337 334 -3 -0.89

5 339 336 -3 -0.88 As seen from the table above, for five (5) observations, it is clear that during enzyme wash the value of fabric surface density finally decreased though ends/inch (EPI) and picks/inch (PPI) increased.


37

13.9.2.3 Changes of Fabric strength after washing

Table 5: Effects of enzymatic wash on fabric strength

No. of Observation

Before wash(gm)

After wash(gm) Difference(gm) % of


Change

1 460 300 -160 -34.78

-33.68

2 455 305 -150 -32.96

3 465 315 -150 -32.25

4 470 310 -160 -34.04

5 465 305 -160 -34.40

From the table as above, for five (5) observations, it is clear that after enzyme wash the Seam strength of denim fabric strength has been decreased from the values obtained before washing.

13.9.2.4 Changes of Seam strength after washing

Table 6: Effects of enzymatic wash on seam strength

No. of Observation

Before wash(gm)

After wash(gm) Difference(gm) % of


Change

1 85 67 -18 -21.17

-22.334

2 83 65 -18 -21.68

3 87 66 -21 -24.13

4 86 67 -19 -22.09

5 84 65 -19 -22.61

From the table as above, for five (5) observations, it is clear that after enzyme wash the Seam strength of denim fabric strength has been decreased from the values obtained before washing.

13.9.2.5


38

13.9.2.6 Changes of Stiffness after washing

Table 7: Effects of enzymatic wash on fabric Stiffness

Direction

Side

No. of Observation

Before wash(gm)

After wash(gm)

Difference(gm)

% of Difference

Warp

Face

1 4.45 2.8 -1.65 -37.08

2 4.55 2.9 -1.65 -36.25

Back

1 3.75 2.6 -1.15 -30.67

2 3.80 2.5 -1.30 -34.21

Weft

Face

1 2.40 2.3 -0.1 -4.17

2 2.35 2.2 -0.15 -6.38

Back

1 2.30 2.5 -0.2 -8.69

2 2.30 2.4 -0.1 -4.35

From the table for two (2) observations along the warp and weft directions for both face and back side of denim fabric, it is clear that after enzymatic desizing process, size materials were removed from the fabric and for softening, the stiffness of denim fabric has been decreased which indicating the increase of fabric softness.

13.9.3 Discussion Denim trousers were chosen as apparel and after washing, changes on characteristics of denim trousers has been observed. It is concluded that after enzyme wash the denim fabric changed from harsh to softer. Due to abrasion damage ends/inch and picks/inch of denim fabric has been decreased and as a result surface density of fabric increased. Again tensile strength of fabric and seam strength of trousers has been decreased due to enzyme washing. Stiffness of denim fabric has been decreased after washing which results in the increase of denim fabric softness. To hold the qualities of sewn apparel it is very necessary to observe the effects of enzyme wash on denim apparels.


39

13.10 Textile Auxiliaries Textile auxiliaries such as dyes could be produced by fermentation or from plants in the future (before invention of synthetic dyes in the nineteenth century many of the colors used to dye textiles came from plants e.g. woad, indigi and madder). Many microorganisms produce pigments during their growth, which are substantive as indicated by the permanent staining that is often associated with mildew growth on textiles and plastics. It is not unusual for some species to produce up to 30% of their dry weight as pigment. Several fo these microbial pigments have been shown to be benzoquinone, naphthoquinone, anthraquinone, perinaphthenone and benzofluoranthenequinone derivatives, resembling in some instances the important group of vat dyes. Microorganisms would therefore seem to offer great potential for the direct production of novel textile dyes of dye intermediates by controlled fermentation techniques replacing chemical syntheses, which have inherent waste disposal problems (e.g. toxic heavy metal compounds). The production and evaluation of microbial pigments as textile colorants is currently being investigated. Another biotechnological route for producing pigments for use in the food, cosmetics of textile industries is from plant cell culture. One of the major success stories of plant biotechnology so far has been the commercial production since 1983 in Japan of the red pigment shikonin, which has been incorporated into new range of cosmetics. Traditionally, shikonin was extracted from the roots of five year old plants of the species Lithosperum erythrorhiz where it makes up about 1 to 2 per cent of the dry weight of the root,. Din tissue culture, pigment, yields of about 15 per cent of the dry weight of the roof cells has been achieved.

13.11 Enzymatic Decolorization In textile dyeing as well as other industrial applications, large amounts of dyestuffs are used. As a characteristic of the textile processing industry, a wide range of structurally diverse dyes can be used in a single factory, and therefore effluents from the industry are extremely variable in composition. This underlines the need for a largely unspecific process for treating textile waste water. It is known that 90% of reactive dyes entering activated sludge sewage treatment plants will through unchanged and be discharged in to rivers. High COD and BOD, suspended solids and intense colour due to the extensive use of dyes characterize wastewater from textile industry, especially process houses. This type of water must be treated before discharging it into the environment. The water must be decolorized; harmful chemicals must be converted into harmless chemicals. Biological treatments have been used to reduce the COD of textile effluents. Physical and chemical treatments are effective for color removal but use more energy and chemicals than biological processes. They also concentrate the pollution into solid or liquid side streams that require additional treatments or disposal, on the contrary biological processes completely mineralize pollutants and are cheaper. Instead of using the chemical treatments, various biological methods can be used to treat the water from the textile industry. These methods include, Biosorption, use of Enzymes, Aerobic and anaerobic treatments etc. Only biotechnological solutions can offer complete destruction of the dyestuff, with a co-reduction in


40

BOD and COD. In addition, the biotechnological approach makes efficient use of the limited development space available in many traditional dye house sites.

14 Enzyme Inactivation To prevent any damage of the fabric after the finishing operation it is very essential that the reaction be terminated at the end of treatment by enzyme inactivation. If the enzyme is not inactivated entirely then at the end of the reaction fibres get damaged and even extreme cases total destruction of the material may result. The enzyme inactivation is therefore of great importance from the technical point of view. There are two distinct process of termination of enzyme: 1) Hot treatment at 800C for 20 min. 2) By raising the pH to 11–12.

15 Why the industry owner should use Bio-technology in textile processing

The importance of using bio-technology in Textile is worth-mentioning. Let us know

some of them- Enzymatic process enhances the variety of plants used in Textile Fibre productions. It

also influences the inner properties of fibres. It is very useful during waste managing. Prevents the adulteration. Bio-technology helps the quality control. Enhance the low energy type detergents. Using enzymes in finishing department. Used instead of harmful dyestuffs and chemical treatments. Tend to use micro-organism and bio-polymer in Textile which develops the total process

of textile. Bio-Stonewashing has opened up new possibilities in denim finishing by increasing the

variety of finishes available. For example, it is now possible to fade denim to a greater degree without running the risk of damaging the garment. Productivity can also be increased because laundry machines contain fewer stones or no stones and more garments.

Hopefully, the uses of Bio-Textile are increasing day by day.


41

16 Conclusion It can be seen from what has been discussed that the field of the biotechnology remains one of the most promising for textile industry to seek out high quality, high added value finishes. Collaboration with biotechnology field to make the research product for the textile industry into the commercial reality in the textile finishing plant will be needed to decrease the lead time environment problem and minimize the profitability innovation and novelty in the enzyme will be necessary to stimulate the more discerning the consumer market and to develop specialty and niche market for textile fabric industry. Bio-processing with its pervasive field of application surely going to conquer the world of textiles and will make it to rich the pinnacle of its performance. There are few to enunciate, however many such potentials are yet to explore. Bio-processing in textiles provides to be a boon to the ever changing conditions of the ecology as well as economy.


42

Reference 1. “Bio- Processing Of Textiles” by Abhishek Jadhav & Javed Sheikh. 2. “Chemistry & Technology of Fabric Preparation & Finishing” by Dr. Charles Tomasino. 3. “Applying Enzyme Technology for Sustainable Growth” by Guifang Wu, Han Kuilderd &

Sonja Salmon (Novozymes). 4. “Bio Polishing of Knit Goods” by Prof. S.K. Laga, Prof. Dr. A.I. Wasif & Mr. Karan Shah

(Textile & Engineering Institute, Ichalkaranji). 5. “CIRCOT’s Eco-friendly Process for Scouring of Cotton Textile: Bio-scouring” –Annual

article of Central Institute for Research on Cotton Technology, Mumbai. 6. “Bio-vision in Textile Wet Processing Industry- Technological Challenges” by C.

Vigneswaran, N. Anbumani and M. Ananthasubramanian. Journal of Textile & Apperal, Technology & Management; Volume 7, Issue 1, spring 2011.

7. “Effects of industrial enzyme wash on denim apparel characteristics” by M. M. Rahman, Daffodil International University. www.ptj.com.pk ; January 2011.

bio processing of textiles - md. rafsan jany

Engineering

textile processing

role of bio

advantages of bio

concentration of enzymes

conventional scouring

role of enzymes

history of enzymes

textile auxiliaries