The word Enzymes came from a Greek word ‘Enzymos’, which meaning ‘in the cell’ or ‘from the cell’. Enzymes are protein substances, produced by the living cells. It’s a are high-molecular weight proteins that consist of intertwined chains of amino acids. It is made up of more than 250 amino acids. Most of the enzymes used in the textile chemical processing are “hydrolase”. The application of enzymes in textile chemical processing has gained increased interest due to the advantages of enzymes being non-toxic, bio-degradable, and eco-friendly.
Types of Enzyme:
The International Bio-chemical Union called “Enzyme Commission” standardized a method of classification giving every enzyme an “EC number” with 4 digits.
According to the reaction methodology and the degree of specificity to catalyze a particular reaction, the enzymes have been categorized into 6 classes.
- EC 1 -Oxido Reductase
- EC 2 – Transferase
- EC 3 – Hydrolase
- EC 4 – Lyase
- EC 5 – Isomerase
- EC 6 – Ligase
Then, it is given the EC number with 4 digits
- 1st digit (Enzyme class),
- 2nd (sub-class)
- 3rd digit (sub-class)
- 4th digit (order number in the sub-class)
Most of the enzymes used in the textile chemical processing belong to class 3: “hydrolase”. The hydrolases family includes with amylases, cellulases, pectinases, proteases, etc. The 2nd number of enzyme code for hydrolases, that describes the type of bond the enzyme hydrolyses and the third number further defines the reaction catalyzed.
Example: An enzyme with first two numbers 3.2 is a hydrolase. Those catalyses the hydrolysis of glycosidic bonds – bonds between carbohydrate residues in polymers like starch and cellulose.
Enzyme Treatments of Textiles Uses and Effects:
|Types of Enzymes||Textile Uses and Effects|
|Cellulases||Bio-finishing, bio-polishing, anti-pilling, softness, smoothness, lustre-improvement and stone-washed Effects on denim.|
|Amylases||Standard procedure for the removal of starch warps size.|
|Proteases||In household washing agent’s better removal of protein containing soil orstains. Anti-felting of wool, accompanied by high loss of weight, tear-strength, degumming of silk with the problem of silk fibroin damage.|
|Lipases||In detergents for the hydrolysis of lipids.|
|Pectinases||Hydrolysis of pectins, for example in cotton ‘preparation’ and retting of flax and hemp.|
|Catalases||Catalyse the decomposition of hydrogen peroxide, important before reactive dyeing of printing of peroxide bleaching fabrics and yarn.|
|Peroxidases||Used as an enzymatic rinse process after reactive dyeing, oxidative splitting of hydrolysed reactive dyes on the fibre and in the liquor, providing better wet fastness, decolourised waste water and potentially toxic decomposition compounds (aromatic nitro-compounds).|
|Ligninases||Removal of burrs and other plant compounds from raw wool.|
|Collagenases||Removal of residual skin parts in wool.|
|Esterases||In development: polyester finish, removal of 01 isomers.|
|Nitrilases||In development: polyacrylonitrile preparation for better coloration.|
Application of Enzymes in Textile Processing:
|Oxidoreductase||EC 1||Dyeing.||Catalyzes the transfer of electrons from one molecule, also called the hydrogen or electron acceptor.|
|Laccases||EC 220.127.116.11||Discoloration of textile effluent. Bleaching of lignin contained fibers and indigo in denim fabric.||Degrade a wide range of recalcitrant (unruly) organic compounds including lignin.|
|Catalases||EC 18.104.22.168||Removal of hydrogen peroxide after bleaching.||In situ peroxide decomposition.|
|Lipases||EC 22.214.171.124||Make polyester hydrophilic, a substitute for alkaline hydrolysis.|
|Split fats and oils into glycerol and fatty acids.|
Remove most difficult lipid stains during washing.
|Amylase||EC 3.2.1||Starch desizing.||Split starch into dextrin and sugars.|
|Cellulase||EC 126.96.36.199||Stone washing|
Bio-finishing for handle modification
Carbonization of wool.
|Degrade cellulose into soluble products.|
|Proteases||EC 3.4||Removal of protein stains during scouring.||Split proteins into soluble polypeptides and amino acids.|
|Pectinases||EC 188.8.131.52||Bio-scouring substituting caustic soda boils.||Degrade pectin.|
|Xylanase||EC 184.108.40.206||Bleaching.||Degrade hemi-cellulose by breaking linear polysaccharide beta-1,4- xylan into xylose.|
Application of Enzymes in Textile Chemical Processing:
Enzymes have a bright future in chemical processing of textile industry. The concept of treating fabrics with enzymes was first developed in 1989in Japan. It can be safely used in textile chemical processing like desizing, scouring, bleaching, dyeing, etc.
Enzymes in textile chemical processing found wide application in the textile industry. Cause:
- No severe damage to surface of fabric.
- Act only on specific substrates.
- Can replace harsh chemicals.
- Operate under mild conditions.
- Accelerate reactions.
- Are safe and easy to control.
- Increased luster of fabrics.
- Can apply on cellulose and its blend.
- Eco friendly treatment.
- Are biodegradable, etc.
Application of enzymes in various textile chemical processing processes is obliged textile industry with respect to both environmental impact and quality of product. There are nearly 7000 known enzymes. But only 75 are used in textile industry commercially. Most of them are belongs to hydolases and oxidoreductases families.
The enzymes used at various stages of textile chemical processing:
|Scouring:||Pectinase, cellulase, cutinase|
|Finishing:||Cellulase, oxidoreductase, lipase|
|Composting of textile waste:||Laccases, cellulase, protease, nylonase, polyesterase|
All applications of enzymes are briefly described.
Enzymes are bio-chemicals which are used to remove starch-based size for improved and uniform chemical processing. It’s contained within all living system and carries out many functions.
Specially formulated desizing enzymes:
|RUCOLASE CGO||Optimum effect above 80°C temperature for exhaust.||Good wetting, cleaning and emulsification. GOTS approved.|
|RUCOLASE HCC||Thermo stableupto120°C temperature for pad steam.||Rapid desizing for uniform and optimum efficiency.|
|TULACHEM DESIZE HT||Exhaust at 60-80°Ctemperature.||Effective processing on Jigger, high turbulence machines.|
|RUCOLASE HCH||Wide temp stability. For pad and exhaust||Universally applicable in all desizing process.|
|TULACHEM DESIZE PAD||Pad-batch.||Low temp stable for uniform and optimum efficiency.|
Amylase is a hydrolytic enzyme catalyses that breakdown of dietary starch to short chain sugars, dextrin and maltose. It’s only amylase family of enzyme have an action on starch (Amylose and Amylopectin). These amylases convert the starch mixture very quickly to soluble dextrin. Then more slowly convert this to reducing substances and sugar, like maltose.
Enzymatic Desizing Process (Starch to Alpa glucose)
Alpha Glucose (Soluble)
Enzymes have disadvantaged that if temperature and pH are not favourable, their desizing activity will be destroyed. Then passing fabric from the desizing solution is batched for 8 to 12hr. During that time, starch is converted into soluble alpha-glucose from insoluble starch. This water-soluble product can be easily washed out. An amylase enzyme uses for desizing processes at the temperature 30-60ºC and optimum pH 5.5 to 6.5.Some common of desizing enzymes uses for different temperature and pH ranges.
Scouring is the process of removing natural waxes, pectins, fats and other impurities from the surface of fibers. Alkaline chemicals such as caustic soda are used for scouring.
But the bio-scouring of raw cotton is an alternative to alkaline scouring. The basic idea is hydrolyzing those non-cellulosic components responsible for water repellency by using enzymes. It is done by using a specific degradation process in delicate pH and temperature conditions. Then removing them with a successive hot rinse. The pectinase will be destroyed the structure of the cuticle, hydrolyzing the pectins. And removing the links with wax and protein.
A company named Huntsman developed a stabilizer that maximizes the wetting and detergency of this bleaching process. A one-bath caustic neutralizer and peroxide remover in order to shorten the bleaching cycle, also reduce the energy and water.
Huntsman developed the surfactants that are eco-friendly system is both Oeko-Tex and GOTS approved. After fabric/yarn bleaching, a step called Bleach Clean-up, residues of hydrogen peroxide are left in the bath, and need to be completely removed prior to the dyeing process.
The traditional method is to neutralize the bleach with a reducing agent and remains have removal results with distinct change of poor dying colour shade and intensity.
Enzymes used for bleach clean-up to ensure that residual hydrogen peroxide from the bleaching process. It’s removed efficiently. A small dose of catalase breakdown the hydrogen-peroxide into water& oxygen. In this way, it reduced water consumption.
Any peroxide on the fabric after bleaching can interfere with the dyeing process. So, removing of peroxide is very important. An amyloglucosidase or, pullanase mixture enzyme is used to degrade starch into glucose during desizing. The generated glucose is converted to hydrogen peroxide and gluconic acid by glucose oxidase enzyme. The gluconic acid was a good peroxide stabilizer during bleaching.
Enzymatic Bio-Finishing or Bio-polishing:
Bio-finishing with cellulase is carried out both on pieces as well as made up apparels and it can be carried out before or after dyeing. Matzyme BIO-F is a cellulase enzyme, which eliminates the dead cotton. Matzyme DS is very effective in de-pilling as well as surface hair removal.
Enzymatic Bio-Stoning or Bio-Washing:
Two types of enzyme washes for denim:
1. Stone-wash: It is done to get stone-wash effect to denims. Cellulase enzymes are natural proteins that are used in denim processing to get stone wash look on to the denim without using stones. Cellulase enzayme attacks basically on surface of cellulose fibre, leaving the interior of the fibre as it is, by removing the indigo present in the surface layer of fibre. Matzyme BIO-W is a cellulase enzyme which can give excellent stone-wash effects.
2. Cellulase-wash: It is done to get a wash down appearance on denim. Under certain conditions, it have ability to react with cellulose will result in surface fibre removal. This gives garments a washed appearance and soft hand. Matzyme BIO-G is especially designed for this cellulase washing of denim garments with low back-staining that offers improved lustre.
1. Degumming of silk: Enzyme degumming of silk is popular in China. The enzymatic process takes more time than that of synthetic detergent but lesser time than that of soap. The recommended proteolytic enzymes are trypsin (of animal origin), pepsin, and papain (of vegetable origin).
2. Degumming of ramie: Ramie fibre is used in textile and the biomass industry. But ramie fiber can usable if non-cellulose materials are removed by degumming. The Calcium ion activated composite enzyme is employed for degummed ramie fiber. The gum, hemicellulose, and lignin were removed by this degumming Process.
Shrink-proofing for Wool:
Xylanase and pectinase enzyme treatments had cleaning efficiency as good as conventional soap scouring. The effect of enzyme treatment on the physical, chemical, and structural properties of wool. These two enzymes never caused any physical damage to the fibers.
Surface Modification of Synthetic Fibers:
The hydrophilicity of hydrophobic synthetic fibers may be improved by alkaline or acid hydrolysis. But it may lead to the deterioration of fiber mechanical properties. Enzymes can easily act on synthetic materials. The advantage of enzymatic treatment over conventional techniques is the favourable bulk properties of PET (polyethylene terephthalate) remain. The enzymatic treatment resulted in significant depilling, efficient desizing, increased hydrophilicity and also reactivity.
The use of enzymes in natural and synthetic thickener systems while printing of cotton and wool has been investigated. These studies especially covered their effects on color and surface structure. The efficiency of different enzymes (cellulases, proteases, and laccases) concerning their applicable within different thickener systems. The enzymatic washing improves the total quality of the printed cotton fabrics. It also decreases the harmful effects of wastewater, and environmental pollution caused by the thickeners and the process time also.
Enzyme-assisted Dye and Dyeing:
Many micro-organisms produce pigments during their growth. The substantive is associated with mildew growth on textiles. Some micro-bial pigments (like: benzoquinone, naphthoquinone, anthraquinone, perinaphthenone, benzofluoanthene) quinine derivatives resembling vat class of dyes. Micro-organisms offer great potential for the direct production of novel textile dyes.
Biological Effluent Treatment:
The natural micro-organisms utilize bio-degradable organic matters. Municipal wastewater, industrial effluents containing oxygen demanding substances like: starch, fat, protein, acid, alcohol etc. The aerobic metabolism of aquatic micro-organisms predominates when oxygen is available. The end products of such metabolism are less non-objectionable. Fungal bio-mass would be a nonessential product of various industrial fermentation processes. It can also be used to remove dyes from Enzyme applications in textile chemical processing dye house wastewater.
Enzymes should be used so that develops can environmentally friendly alternatives to chemical processes in all steps of textile fibre processing. It’s commercially successful applications, like amylases for desizing. It still considerable potential for new and improved enzyme applications in future textile chemical processing. But enzymes have the advantage of being non-toxic, bio-degradable, and environmentally-friendly.
- Sustainable Technologies for Fashion and Textiles Edited by Rajkishore Nayak
- Textile Processing with Enzymes Edited by A. Cavaco-Paulo and G. M. Gübitz
Author of this Article:
Md Mahedi Hasan
B.Sc. in Textile Engineering
Textile Engineering College, Noakhali.