MD SOHEL KHAN

Students ofPORT CITY INERNATIONAL

UNIVERSITY

BIO-SCOURING

Introduction

Bioscouring is a process by which alkaline stable pectinase is used to remove pectin and waxes selectively from the cotton fibre.

Pectinase, as the name suggests, hydrolyses pectins present in cotton as a non-cellulosic impurity.

Types of enzymes that are used for bio-scouring process: Pectinase:-Pectinases are used for the removal

pectic substances from cotton.

Lipases :- They are used for the removal of natural fatty substances from cotton

proteases:- proteases are enzymes that catalyse the hydrolysis of proteins.

Mechanism of bio-scouring The following two stages mechanisms are

involved in bio-scouring Stage :1

Removal of wax ( a major part being fatty acids, alcohols and esters) is the critical factor for improved wettability.  Pectin functions as a ‘glue’ binding wax to the fibre. Pectin removal  does not by itself result in wax removal or improved wettability but it renders wax extractable or emulsifiable.

Presence of  Ca++ slows down the removal pectin and fatty acid, so a sequestrate should, if compatible, be applied with the enzyme – otherwise after the enzyme reaction.

                       

continued Stage 2:

                                     2/3 or more of the pectin must be

dissolved in order to be able to emulsify enough wax for a good wettability for dyeing.

Emulsification is strongly enhanced at temperatures above the wax melting point, i.e. >70°C

Bio-Scouring Process:

                    Important process parameters

pH and Temperature Wetteners  Emulsifiers Pectinase enzyme

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 Emulsifier ………………………………………. 0.5-

1.5 g/l Temperature : .....................................60oC Time : ................................................30 min M: L : ................................................1:10 PH : ...................................................6-9

Here, 1. Water,wetting agent, PH buffer and fabric; 2. Enzyme (pectinase); 3. Emulsifier. Figure: Bioscouring processing curve

Comparison of Bio-Scouring and Alkali Scouring

Bio-scouring

Blend of Enzymes-Pectinase + Protease

Removes Pectin, protein, Wax, Oil etc

Alkaline-scouring

Sodium Hydroxide

Remove Pectin, Protein, Wax, Oil, Cellulose

Results of Bio and Alkaline scouring

Bio-scouring

Soft Handle

cellulose with complete removal of Impurities

No core Alkali neutralization, thus less washing cycle

Less TDS, COD, BOD

Alkaline-scouring

Harshness

cellulose with complete removal of Impurities and partial Callulose

Required core alkali neutralization, thus more washing cycle

More TDS, COD, BOD

Cost

Bio-scouring

Direct cost is more but Overall cost is less

(Grey to finished)

Alkaline-scouring

Direct cost is less

but Overall cost is more (Grey to finished)

.

Examples of Bio-Scouring and Alkaline Scouring

Advantages of Bio-scouring

Save energy Save cost Water saving Temperature saving Time saving Smoother surface profile(Fully retain cellulose structure) Lesser weight loss Lesser costs of auxiliaries Mild application condition Environmental benefits Reduces effluent treatment process/ ETP cost

Disadvantage of bio-scouring

Inability of removing of cotton fiber waxes.

Enzyme activity can, however, be reduced or even completely destroyed (denatured) by high temperatures, extremes of pH and high concentrations of electrolytes that destroy their three-dimensional structures. Heavy metal ions and oxidizing and reducing agents also deactivate the enzymes.

The degree of whiteness is often less and the process is not suitable for removing seed-coat fragments and mote adequately.

Summary

Though the conventional scouring process is extremely using now-a-days, it has great bad effect on environment.

Many of the developed countries are avoiding the convention-al scouring process replacing enzymatic, ecofriendly, scouring processes.

Bioscouring is an eco-friendly scouring process it has great future.

The new enzymatic procedure is corresponding with a significant role in minimising the de-mand of energy, water, chemicals, time and costs.

Thank you