STUDY ON ENZYMATIC TREATMENTS ON TEXTILE GOODS

Abstract: Amylase, Protease, Cellulase, Catalase, Laccase, Pectinase etc. are widely used in textiles. In Bangladesh we found the use of amylase, cellulase, catalase widely rather than other enzymes. we have described many aspects of application of enzymes in textile with application methods, conditions, mechanisms and affects on the end products & environment with experimental data. Health and safety issues also included here. 

We have studied the effect of bio-polishing by using acid stable cellulase enzyme in different circumstances. 

Enzyme:

Enzyme is specialized high molecular weight protein produced within an organism, which is capable of catalyzing specific chemical reaction. They are also known as "Biocatalyst". 

Source of enzyme:                                               

• Vegetable source
• Bacterial source
• Animal source

  Classification of enzyme:

Oxidoreductase

↓

Transferase

↓

Hydrolase

↓

Lyase

↓

Isomerase

↓

Ligase or Synthetase

The history of enzymes in textile:

1. Amylase at desizing in 1952
2. Catalase at bleach cleanup in 1993
3. Pectinase at bio-scouring in 2003

Lock and key model

Enzyme used in textile processing
process	Types of enzyme used
Desizing	Amylase
Scouring	Pectinase
peroxide killing	Catalase
Denim bleaching	Laccase
Bio polishing	cellulase
Anti-shrink & Anti felting on wool	protease

• enzyme
• Hydrolase class of enzyme.
• Used for desizing.
• Hydrolyses 1-4 α glucosidic linkage of amylase and amylopectin of starch to convert them into soluble dextrins.

Process of desizing with amylase: 

Cellulase

1. Hydrolase class of enzyme.
2. Used for bio-polishing and stone washing effects.
3. Used in detergent formulations to enhance detergency, improve brightness & remove microfibrils.

Mechanism of cellulase enzymes on cellulosic Fibers

1. There are four main actions-
2. Endocellulase cleave the long cellulose chains randomly to produce two shorter chains.
3. Exocellulase attack one end of the cellulose chain, cleaving one glucose unit at a time.
4. Cellobiohydrolase similarly act on one end of the cellulose chain, producing a cellobiose molecule.
5. Cellobioase degrade cellobiose molecules to the simplest glucose unit.

Mechanism of cellulase enzymes on cellulosic fibers

pectinase:

1. Used for bio-scouring.
2. BOD & COD are (20-45)% of alkaline scouring (100%).
3. TDS is (20- 50)% of alkaline scouring (100%).
4. Handle is very soft compared to harsh feel in alkaline scouring.
5. Highly suitable for blends containing fibers like wool, silk, viscose, modal, lyocell, lycra etc.

cataiasa:

• Oxidoreductase class of enzyme.
• Catalase is used for the removal of H2O2 after bleaching.
• One catalase molecule can convert 40 million molecules of hydrogen peroxide to water and oxygen per second.

Scouring:

• Sodium Hydroxide  :   2.5 %
• Sodium Carbonate  :   1 %
• Cidascour LTJ  :  0.5 %
• Wetting agent  :   0.5 %
• Sodium hexametaphosphate  :   0.2 %
• Temperature  :   80 °C
• Time  :  4 – 5 hours
• pH  :   9 – 10
• M : L   :   1 : 20

Bleaching:

• Hydrogen peroxide (50%) : 0.5 – 1 % 
• Sodium silicate : 1 % 
• Sodium hexametaphosphate : 0.2 % 
• Temperature : 85 °C 
• Time : 2 hours 
• pH : 10–10.5 
• M : L : 1 : 20

One bath scouring and peroxide bleaching:

• Sodium hydroxide : 2.5 % 
• Lissapol D : 0.5 % 
• Hydrogen peroxide : 2 – 3 % 
• Sodium silicate : 1.5 % 
• Sodium hexametaphosphate : 0.2 % 
• Temperature : 80 °C 
• Time : 2 – 3 hours 
• pH : 10 – 10.5 
• M : L : 1 : 20

Bio-polishing recipe:

• 
  
• BP Nano(Cellulase) : 0.9 g/l
• Acetic acid : 1 g/l
• T-100 (Peroxide killer) : 0.08 g/l
• Securon 540(Seq. agent) : 0.25 g/l
• Temperature : 55-60 °C
• Time : 40-60 min.
• pH : 4.5-5

Discussion:

1. The best result is obtained at 1:10, M : L and 3% concentration 
2. Enzyme shows maximum activity at pH (5 – 5.5) & 55 °C temperature . But optimum bio-polishing is obtained at pH 4-5.
3. The best bio-polishing  effect is obtained at 50 min. treatment time. 
4. Depth of shade increases when enzyme treatment is given before dyeing and the depth decreases when enzyme treatment is given after dyeing. 
5. Pilling tendency decreases with application of enzyme. 
6. One bath bio-polishing effect is not as good as the two bath method. 

Conclusion:

• Chemical processes have inherent drawbacks from commercial and environmental point of view.
• Harsh and hazardous chemical processes involving high temperature, pressure, acidity, or alkalinity, need high capital investment and specially designed equipment and control systems.
• Enzymes have contributed to more environmentally adapted processes because they are bio-degradable, they can replace harsh chemicals and they reduce high temperatures & pressures.

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