What is an enzyme? Its different uses in textile.

                                       

What is an enzyme? 

Enzymes are proteins that act as organic catalysts or bio-catalysts. Catalysts accelerate chemical reactions. The molecules on which enzymes can work are called substrates and the enzymes convert layers into different molecules known as products. The study of enzymes is called enzymology. In 1877, the German physicist Wilhelm Kühne first used the term enzyme to describe this process, which comes from the Greek ἔνζυμον, fermented or yeast. The term enzyme was later used for lifeless things like pepsin, and the term ferment was used to refer to the chemical activity produced by living organisms.

The EC classification system is divided into six categories of basic function-

a. EC 1, Oxidoreductases: catalyze oxidation/reduction reactions

b. EC 2, Transferases: transfer a functional group (e.g. a methyl or phosphate group)

c. EC 3, Hydrolases: catalyze the hydrolysis of various bonds

d. EC 4, Lyases: cleave various bonds by means other than hydrolysis and oxidation

e. EC 5, Isomerases: catalyze isomerization changes within a single molecule

f.  EC 6, Ligases: join two molecules with covalent bonds.

Each enzyme is described by a sequence of four numbers preceded by “EC”. The first number broadly classifies the enzyme based on its mechanism.

Working Condition

Enzymes can work at atmospheric pressure and in mild conditions with respect to temperature and acidity (pH). Most enzymes function optimally at a temperature of 30ºC-70ºC and at pH values, which are near the neutral point (pH 7). Enzyme processes are potentially energy-saving and save investing in special equipment resistant to heat, pressure, or corrosion. Due to their efficiency, specific action, the mild conditions in which they work, and their high biodegradability, enzymes are very well suited for a wide range of industrial applications. Enzymes are used in the textile industry because they accelerate reactions, work only in certain layers, work in mild conditions, are safe and easy to control, can replace harsh chemicals, and enzymes are biodegradable, that is, biodegradable.

Features of Enzyme-

a. An enzyme accelerates the reaction.

b. Enzymes operate under milder conditions.

c. Alternative for polluting chemicals.

d. The enzyme acts only on a specific substrate.

e. An enzyme is easy to control.

f. Enzymes are biodegradable.

Enzyme applications in textile-

Especially in textile manufacturing, the use of enzymes has a long tradition. The current application in the textile industry involves mainly hydrolyzes and now to some extent is oxidoreductase. The enzymatic resizing of cotton with α-amylase is a state-of-the-art for many decades. Moreover, cellulose, pectinases, hemicelluloses, lipases, and catalyzes are used in different cotton pre-treatment and finishing processes. Other natural fibers are also treated with enzymes. Examples are enzymatic degumming of silk with sericinases, felt-free finishing of wool with proteases, or softening of jute with cellulose and xylanases. In the future, also synthetic fibers such as polyester or poly-acrylonitrile will be modified by enzymatic treatment. The application of enzymes has many advantages compared to conventional, non-enzymatic processes. Enzymes can be used in catalytic concentrations at low temperatures and at pH values near neutral. In addition to cellulose, cotton contains so-called primary wall natural compounds such as pectin, hemicelluloses, proteins, waxes, and lignins that can damage the finishing result. In conventional pre-treatment, these substances are removed by a strong alkaline treatment at high temperatures after an enzymatic design of raw cotton fabrics with α-amylase. This is a specific alkaline scouring process that has high energy, water, and alkali consumption and can also cause damage to the cellulose material.

Enzymatic Desizing

In the textile industry amylases are used to remove starch-based sizing for improvement and uniform wet processing. Amylase is a hydrolytic enzyme that catalyzes the breakdown of dietary starch into short-chain sugars, dextrin, and maltose. The advantage of these enzymes is that they are specific for starch, removing it without damaging the support fabric. An amylase enzyme can be used for de-sizing processes at low-temperature (30-60ºC) and the optimum pH is 5.5- 6.5.

Enzymatic Scouring (Bio scouring)

Scouring is the removal of non-cellulosic material present on the surface of the cotton. In general cellulose and pectinase are combined and used for Bio-scouring. This pectinase digests the pectin and destroys the cuticle structure of the cotton by removing the connection between the cuticle and the cotton fiber body where cellulose can destroy the cuticle structure by digesting the primary wall cellulose under the cotton cuticle. Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) of the enzymatic scouring process is 20-45 % as compared to the alkaline scouring (100 %). Total Dissolved Solids (TDS) of the enzymatic scouring process is 20-50% as compared to the alkaline scouring (100%). The handle is very soft in enzymatic scouring compared to the harsh feeling in the alkaline scouring process. Enzymatic scouring enables you to rub the fabric effectively without adversely affecting the fabric or the environment. It also minimizes health risks and operators are not exposed to aggressive chemicals.

Enzymatic Bleaching

The purpose of cotton bleaching is to decolorize natural pigments and to confer a pure white appearance to the fibers. Mainly flavonoids are responsible for the color of cotton. The most common industrial bleaching agent is hydrogen peroxide. Conventional preparation of cotton requires high amounts of alkaline chemicals and huge quantities of rinse water are generated. However, radical reactions of bleaching agents with the fiber can lead to a decrease in the degree of polymerization and thus, to severe damage. Therefore, the replacement of hydrogen peroxide by an enzymatic bleaching system would not only lead to better product quality due to less fiber damage but also to substantial savings on washing water needed for the removal of hydrogen peroxide. An alternative to this process is to use a combination of suitable enzyme systems. Amylo-glucosidases, pectinases, and glucose oxidases are selected that are compatible concerning their active pH and temperature range. The first time the enhancement of the bleaching effect was achieved on cotton fabrics using lactases in low concentrations. In addition, the short time of the enzymatic pre-treatment sufficient to enhance fabric whiteness makes this bio-process suitable for continuous operations. They found that the supply of low ultrasound energy (7W) enhanced the bleaching efficiency of lactase on cotton fabrics. Natural fabrics such as cotton are usually mixed with hydrogen peroxide before dyeing. Catalase enzyme is used to break down hydrogen peroxide bleaching liquor into water molecules and less reactive gaseous oxygen. Compared with the traditional clean-up methods, the enzymatic process results in cleaner wastewater or reduced water consumption, a reduction of energy and time.

Bio-polishing

Bio-polishing is a finishing process that improves fabric quality by mainly reducing the hairiness and pilling properties of cellulosic fiber. The objective of the process is the elimination of the microfibrils of cotton through the action of the cellulose enzyme. The main features given to the fabric during bio-polishing treatment are as follows:

a. A cleaner surface is obtained conferring a cooler feel.

b. Luster is obtained as a side effect

c. Fabric obtains a softer feel.

d. The tendency of the fabric to pill ends.

Enzymatic treatment to denim

Denim is heavy-grade cotton. This dye is mainly adsorbed on the surface of the fiber. That is why fading can be achieved without considerable loss of strength. In the traditional process sodium hypochlorite or potassium permanganate was used called pumice stones.

The disadvantage of pumice stones is as follows

a. Pumice stones cause a large amount of back-staining.

b. Pumice stones are required in very large amounts.

c. They cause considerable wear and tear on the machine.

These disadvantages lead to give rise to the process of the use of enzymes. Cellulose enzyme is used in denim washing. Cellulose works by loosening the indigo dye on the denim in a process known as “Bio-Stone-washing”. A small dose of an enzyme can replace several kilograms of pumice stones. The use of less pumice stone results in less pumice dust damage to clothing, machinery, and laundry environments. More recently, some authors showed that lactase was an effective agent for the stone-washing effects of denim fabric with and without using a mediator.

Advantages of Enzyme

a. The enzyme removes sizing materials from the fabric or garments

b. It removes the stiffness and hardness of the fabrics.

c. It removes hairiness and pilling on the fabric surface.

d. It gives softness and attractive looks to garments.

Disadvantages of Enzyme

a. Sometimes it reduces the tearing strength of the fabric.

b. Difficult to maintain enzyme concentration.

c. Difficult to optimize.

d. Limits overall success.

e. High cost.

Conclusion

These are just a few applications of Biotechnology, however many such potentials are yet to be explored. Biotechnology finds wide application in textiles and it will prove to be a boon to the ever-changing conditions of the ecology as well as the economy. Pollution-free processes are gaining ground all over the world. In these situations, enzymes are emerging as the best alternative to contaminating textile processing methods. Enzymes are not only beneficial from an environmental point of view but they are also saving a lot of money by reducing water and fuel costs which ultimately reduces production costs.