Bio-Scouring Process: Enzymes, Steps, Benefits & Applications

Bio-Scouring Process: A Sustainable Bio-Scouring Process for Better Fabric Dying

Shahadat Hossain
B.Sc. in Textile Engineering
Textile Engineering College, Zorarganj, Chattogram

Abstract:

Bio-scouring is a beneficial and sustainable alternative to traditional scouring, aligning with the growing trend toward greener textile production methods and contributing to high-quality, durable, and environmentally friendly textiles. The use of enzymes in the textile industry can be considered the best possible use of the bio-processing technique. The use of enzyme treatments in the textile industry is very promising, as they are environmentally friendly, produce high-quality products, and reduce the use of water, energy, and time. In production, the enzyme bath is usually matched to the specific fabric and finish, because the best recipe depends on the greige goods, the amount of natural wax, and the machine used.

Keywords: Bio-preparation, bio-scouring, dyeing, cost saving, enzyme treatment.

Introduction:

Bio-scouring is an eco-friendly alternative to traditional chemical scouring processes, used to prepare fabrics, especially natural fibers like cotton, for dyeing. It is usually carried out after desizing and before bleaching or dyeing, because residual size and spin finishes can limit enzyme access to the cotton cuticle, according to Choudhury (2014). Traditional scouring involves harsh chemicals to remove impurities (such as pectin, waxes, and oils) that can inhibit dye uptake. Enzymatic treatment, i.e. bio-scouring, provides an environmentally friendly alternative. The biggest advantage of bio-scouring is that it does not destroy the cellulose structure and hence prevents the loss of cellulose weight and stress. The enzymatic process called bio-scouring allows cotton to be treated under very mild conditions. Due to use of less rinse water, bio-scouring process reduces both effluent as well as water consumption. In bio-scouring 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 strength.

Many conditions are important to the performance of the enzymes, such as the concentration of the enzymes in the bath, the time and temperature of treatment, the pH of the bath, and additives. A small lab trial should be run before bulk production, because enzyme performance can change with fabric construction and the amount of finishing on the cloth. The pH of the environment is crucial for the activity and stability of the enzyme, which ranges between 5 and 9. An alkaline or acidic environment depends on the type of enzyme. Acidic enzymes work in a slightly acidic medium (pH between 4 and 6) and alkaline enzymes work in a slightly alkaline medium (pH between 7 and 9). Care must be taken to monitor the pH, as extreme values lead to collapsing the three-dimensional form of the enzymes and losing their catalytic behavior. A calibrated pH meter is better than test paper when the bath must stay close to the target range. A non-ionic surfactant helps in the smooth functioning of the scouring process.

The main enzyme class used in bio-scouring is pectinases. They are used to specifically remove pectin lattice, the biological “glue”, in the surface of the fiber. In particular, pectin lyases and pectate lyases or transeliminases are used in bio-scouring. Cellulases may assist pectinases by increasing their accessibility to the pectin material. For mill use, the enzyme should be selected by activity units and supplier data sheet, not only by grams per liter, because commercial pectinase preparations can have very different strengths, as discussed by Mojsov (2012).

Preparation of Fabric:

The fabric is prepared by inspecting it and removing any foreign particles. Loose lint, oil spots, and stitch marks should also be removed at this stage, because they can cause patchy scouring and uneven dye uptake later.
Wetting agents may be applied to ensure even distribution of water and enzymes during the treatment.

Enzyme Selection:

Pectinase enzymes are primarily used because they break down pectins, which bind waxes and other impurities to the fiber.
Depending on the fabric composition, additional enzymes like cellulase or lipase may be used to target specific impurities. If the fabric already contains heavy knitting oil or silicone softener, a short prewash with a mild detergent may be needed before the enzyme bath.

Procedure of Bio-Scouring:

According to Pan N. C. et al. (2013) enzymes and non-ionic surface active agents were used for bio-scouring process. The temperature of the bath was maintained at 50°C for 2 hours, keeping the material to liquor ratio at 1:10. The pH of the bath was maintained by using acetic acid and sodium acetate buffer. After the treatment, the temperature of the bath was raised to 90°C and maintained at that temperature for 15 minutes after which the samples were washed and dried. In practice, the same recipe should be checked on a trial sample first, because the best time and temperature can shift with fabric GSM, machine type, and water quality.

Recipe Formulation:

Enzymatic scouring was carried out by the following recipe-

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

The exact dose should be adjusted according to enzyme activity and the level of natural impurities.

Enzyme Inactivation:

After finishing treatment, it is essential to complete the reaction at the end by inactivating the enzyme to avoid damage to the fabric. Failure to inactivate the enzyme at the end results in damage to the fibers and, in extreme cases, the destruction of the whole fabric material. Therefore, from a technical perspective, inactivation of the enzyme is very important.

There are two processes of inactivation of enzyme:

Hot treatment at 80°C for 20 minutes.
By raising the pH to 11-12. After inactivation, the fabric should be rinsed well and checked for near-neutral pH before dyeing.

Action on Impurities:

The enzymes break down the impurities, specifically targeting pectin and waxy substances, which bind the cotton fiber’s non-cellulosic impurities. This makes it easier to remove these impurities without damaging the cellulose. This is why bio-scouring usually improves absorbency and gives a cleaner surface without the harsh fibre loss associated with strong alkali scouring, as described by Choudhury (2014).

Rinsing & Neutralization:

Rinsing:

After enzyme treatment, the fabric is thoroughly rinsed with water to remove the broken-down impurities. A final rinse should be clear and the fabric should not feel slippery, because leftover bath chemicals can affect the next process.

Neutralization:

In some cases, mild acids are added to neutralize any remaining enzymes and adjust the pH back to a neutral or slightly acidic level, which is gentler on the fibers. If the next stage is reactive dyeing, neutralization is especially important because residual alkali can affect shade reproducibility and increase dye hydrolysis.

Drying:

The fabric is then dried through methods such as air drying, tumble drying, or other industrial drying processes. Drying should be done only after thorough rinsing, because trapped liquor can leave the cloth dull or make it harder to rewet in later processing.

Conclusion:

One of the most worrying situations in the textile industry is its environmental impact. Pollution-free processes are becoming more and more popular worldwide. In this context, enzymes are emerging as the new and best alternative to conventional methods of textile processing. Currently, enzymes are being adopted for all types of textile processing that are used in the textile industry, such as bio-scouring. Bio-scouring is biodegradable, environmentally friendly, and the most commonly used wet processing method in the textile industry. Bio-scouring has gained a lot of attention in the textile industry in recent times. The process involves washing the fabric with an enzyme to remove the impurities and waxy material from the fiber. The enzyme hydrolyzes the glucose bond b1-4 and produces a permanent effect. This process removes impurities from the fabric, smooths the surface of the fabric, gives it a cleaner and shiny appearance, makes the fabric softer and cooler, and improves its overall surface appearance. Bio-scouring serves textile processing industries and creates awareness for adopting eco-friendly textile processing methods. It helps the textiles industry grow and thrive in a sustainable manner for future prosperity and happiness For production use, a pilot run with absorbency, whiteness, and tensile-strength checks is the safest way to confirm the recipe on a specific fabric lot.

References:

[1] Agrawal, B. J. 2016. Desizing of cotton fabrics with enzymes for improved performance. International Journal of Industrial Biotechnology and Biomaterials, 2(1).

[2] Bornscheuer, U. T., & Buchholz, K. (2005). Highlights in biocatalysis–historical landmarks and current trends. Engineering in Life Sciences, 5(4), 309-323.

[3] Bristi, U., Pias, A. K., & Lavlu, F. H. 2019. A Sustainable process by bio-scouring for cotton knitted fabric suitable for next generation. J. Text. Eng. Fash. Technol, 5: 41-48.

[4] Choudhury, R. A. K. 2014. Sustainable textile wet processing: Applications of enzymes. In Roadmap to sustainable textiles and clothing (pp. 203-238). Springer, Singapore.

[5] Degani, O., Gepstein, S., & Dosoretz, C. G. 2002. Potential use of cutinase in enzymatic scouring of cotton fiber cuticle. Applied Biochemistry and Biotechnology, 102(1): 277-289.

[6] Gomes, I., Sarkar, P. K., Rahman, S. R., Rahim, M. A., & Gomes, D. J. Production of cellulase from Talaromyces emersonii and evaluation of its application in eco-friendly functional finishing of jutebased fabrics. Bangladesh Journal of Microbiology, 2007. 24(2): 109-114.

[7] Hasan, F., Shah, A. A., & Hameed, A. 2006. Industrial applications of microbial lipases. Enzyme and Microbial technology, 39(2): 235-251.

[8] Mojsov K. Enzyme scouring of cotton fabrics: a review. International Journal of Marketing and Technology (IJMT). 2012;2(9):256–275.

[9] Rajendran R, Sundaram SK, Radhai R, et al. Bioscouring of cotton fabrics using pectinase enzyme its optimization and comparison with conventional scouring process. Pak J Biol Sci. 2011;14(9):519–525.

[10] Li Y, Hardin ZR. Enzymatic scouring of cotton: effects on structure and properties. Cellulose. 1997;94.

[11] Yonghua Li, Ian R Hardin. Enzymetic scouring of cotton: Effect on structure & properties. Textile chemist & colorist. 1997;29(8):71–76

[12] El Shafie A, Fouda MM, Hashem M. One-step process for bio-scouring and peracetic acid bleaching of cotton fabric. Carbohydrate Polymers. 2009;78(2):302–308.

[13] Oksanen T, Pere J, Paavilainen L, et al. Treatment of recycled kraft pulps with Trichoderma reesei hemicellulases and cellulases. J Biotechnol. 2000;78(1):39–48.

[14] Tzanov Tzanko, Margarita Calafell, Georg M, et al. Bio-preparation of cotton fabrics. Enzyme and Microbial Technology. 2001;29(6–7):357– 362.

[15] Sawada K, Tokino S, Ueda M, et al. Bioscouring of cotton with pectinase enzyme. Journal of the Society of Dyers and Colourists. 1998;114(11):333–336.

Frequently Asked Questions (FAQs)

Q1. What is bio-scouring in textile?

Ans: Bio-scouring is an enzyme-based pretreatment used to remove pectin, waxes, and natural impurities from cellulosic fabrics before dyeing. It is a milder alternative to caustic scouring and helps improve absorbency and surface cleanliness.

Q2. Which enzyme is used for bio-scouring of cotton?

Ans: Pectinase is the main enzyme used for bio-scouring of cotton because it breaks down the pectin layer that holds waxes and other impurities on the fiber surface. In some cases, cellulase or lipase is added to help remove specific finishes or impurities.

Q3. What is the difference between bio-scouring and conventional scouring?

Ans: Conventional scouring usually uses strong alkali and high temperature to strip impurities from fabric. Bio-scouring uses enzymes under milder conditions, so it is generally gentler on cellulose and easier on wastewater treatment.

Q4. Does bio-scouring affect fabric strength?

Ans: When it is properly controlled, bio-scouring should have little to no negative effect on cotton strength because it targets non-cellulosic impurities rather than cellulose. Damage usually happens only when the bath is too harsh, the pH is off, or the enzyme is not stopped at the end of processing.

Q5. What temperature is best for bio-scouring cotton fabric?

Ans: Many lab recipes run around 50 to 60°C, but the best temperature depends on the enzyme supplier, fabric construction, and machine type. The safest approach is to run a pilot trial and confirm absorbency and strength before bulk production.