Bioscouring of Cotton Fabrics | Comparison of Bioscouring and Conventional Scouring

Last Updated on 12/06/2021

Bioscouring Process of Cotton Fabrics with Advantages and Disadvantages

Apu Kumar Das
B.Sc. in Textile Technology
Chittagong Textile Engineering College
Email: akdas.textile13@gmail.com

 

Bioscouring of Cotton Fabrics:
With the increasingly important requirement for textile industries to reduce pollution in textile production, the use of enzymes in the chemical processing of fibers and textiles is rapidly gaining wider recognition because of their non-toxic and eco-friendly characteristics. Enzymes were discovered in the second half of the nineteenth century, and since are routinely used in many environmentally friendly and economic industrial sectors. There is increasing demand to replace some traditional chemical processes with biotechnological processes involving microorganisms and enzymes such as pectinases, xylanases, cellulases, laccases and ligninases.

effect of bioscouring
Fig: Effect of bioscouring

The enzymatic process called bio-scouring allows cotton to be treated under very mild conditions. Due to use of less rinse water, bioscouring process reduces both effluent as well as water consumption. In bioscouring alkaline pectinase enzyme is used for natural cellulosic fibers such as cotton, linen, hemp and blends. It removes pectin and other impurities from the primary cell wall of the cotton fibers without degradation of cellulose and thus has no negative effect on strength properties of the fabric.

Bioscouring can also be combined with other wet processes such as follows:

  • Desizing and bioscouring
  • Bioscouring and dyeing
  • Bioscouring and biopolishing
  • Bioscouring, biopolishing and dyeing

Combining these processes offer considerable time, water and energy savings.

Material Preparation:
A single jersey Cotton Knitted fabric having GSM 160 was supplied by the supervisor which consists of dirt, dust, oil, wax etc. We took 4 samples from it each weighing 10 grams. Before the scouring treatment the substrate was washed in distilled water to extract the water soluble constituents and then dried in Laboratory oven dryer. After washing and drying the oven dry weight of the samples were measured in an Electric Balance.

Recipe Formulation:
Enzymatic scouring was carried out by the following recipe-

  1. Enzyme: ………………………………………3 g/L or 0.5%
  2. Sequestering agent : ………………………1 g/L
  3. Wetting agent : ……………………………..2 g/L
  4. Temperature : ……………………………….60oC
  5. Time : …………………………………………30 min
  6. M: L : …………………………………………1:10
  7. pH : ……………………………………………8 -9

Bioscouring Curve:

Bio-scouring Curve.
Figure: Bioscouring Curve.

Bioscouring Procedure:
The required amount of water, chemicals and enzyme were taken for each sample in the individual pot of Washing and dry cleaning colour fastness (Gyrowash). Then the samples were immersed and stirred properly in the solution of the pots. Then the samples were treated in the Gyrowash according to the curve.

Washing and Drying:
After the completion of the bioscouring process the samples were washed with hot water. Then the samples were treated with Acetic acid and washed with cold water and squeezed properly. Then the laboratory oven dryer was used for drying the samples. After washing and drying the oven dry weight of the bio-scoured samples were measured with the help of an Electric Balance.

Comparison of Bioscouring and Conventional Scouring:

Parameters Bioscouring Conventional scouring
pH value of process 8–9.5 13–14
Temperature 50–60 95–100
Residual pectin 10–15 10–15
Weight loss % <2.5 3–8
Hydrophilicity (TEGEWA) <2 s <2 s
Fibre damage (DP component) <0.05 <0.05
Degree of whiteness 5–10 points improved 1–2 points improved
Handle Very soft Harsh
Dyeability Good Good
Water saving 20–50%

Advantages of Bioscouring Process:
Enzymatic bio-scouring is a milder process and certainly more ecofriendly than alkaline boiling off. Advantages of bioscouring of cotton fabrics 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.

Bioscouring has following advantages:

  1. Over 50% reduction of TDS, COD and BOD in the effluent.
  2. Can be combined with enzymatic desizing.
  3. Core alkali migration no longer a problem in further processes.
  4. Overall savings in utilities up to 30% (less water and energy required).
  5. Improved strength when compared to conventional scouring.
  6. Lower weight loss, up to 1–2% compared to 4% of conventional alkaline scouring.
  7. Better softness.
  8. No cellulosic/fibre damage.
  9. Less chemicals used.
  10. Mild conditions allow treatment of linen and blends.
  11. No oxy-cellulose formation and less strength loss because of absence of heavy alkali in bath.
  12. Uniform removal of waxes results in better levelness in dyeing.
  13. Highly suitable for scouring of blends like silk, wool, viscose, modal, lyocel, and Lycra etc.
  14. Low Total Dissolved Solids (TDS) in discharge waste water.
  15. Fabric is softer and fluffier than conventional scouring, ideal for terry towel/knitted goods.
  16. Milder conditions of processing, low consumption of utilities, excellent absorbency in goods.

Disadvantages of Bioscouring:
The apparent efficiency of the bio scouring process was not as efficient as the chemical scouring process. In bio scouring process, the cotton motes were not removed, which warranted peroxide bleaching. Besides, it was observed that, during pectinase scouring, much less wax was removed compared with the alkaline scouring.

References:

  1. Bioprocessing of textiles by Dr. C. Vigneswaran, Dr. M. Ananthasubramanian, Dr. P. Kandhavadivu
  2. Pretreatment of Textile Substrates by Mathews Kolanjikombil
  3. Textile Chemistry by Thomas Bechtold, Tung Pham

You may also like:

  1. Scouring Process of Cotton in Textile Industry
  2. Application of Enzymes in Textile Processing
  3. Effects of Various Enzymes on Denim Garment Washing
  4. Estimation of Scouring Effect by Weight Loss and Absorbency Test
  5. Estimation of Scouring Effect on Cotton by Varying Concentration of Caustic Soda
  6. Determination of Strength & Weight Loss Due to Single Bath Scouring & Bleaching Action on Cotton

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