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Abstract The objective of this study was to develop a new process to desize, bleach, and dye starch-sized cotton fabrics in one bath using enzymes. Desizing was performed with an amyloglucosidase/pullanase enzyme (Dextrozyme DX, manufactured by Novozymes) instead of a conventional amylase enzyme in order to hydrolyze starch into single glucose units. Multifect GO 5000L (Genencor) glucose oxidase enzyme was used to yield hydrogen peroxide from the glucose generated during desizing; bleaching was performed by this enzymatically generated hydrogen peroxide. Decomposition of hydrogen peroxide after bleaching was done with Terminox Ultra 10L (Novozymes) catalase enzyme. The fabric was dyed in the same bath with the selected monochlortriazine reactive dyes (DyStar). The amount of glucose generated during desizing was 4000 ± 135 mg/1 and it yielded 765 ± 15 mg/1 hydrogen peroxide during glucose oxidase enzyme treatment. The whiteness index of the enzymatically bleached fabric was 71.0 ± 1.2 stensby degree. The color yields of the enzymatically treated samples were comparable to the conventionally treated samples. All enzymes used in this study were commercial grades having the advantages of easy storage and supply compared to the pure enzymes used in earlier studies. The advantages of the new one-bath process were: less auxiliary demand; lower environmental impact; and energy and water savings compared to the conventional desizing, scouring, bleaching, and dyeing sequence.
Key words dyeing, enzymes, finishing, processing, waste reduction
Biotechnology has already had a significant impact on tex- tile pretreatment and dyeing technology. A great deal of waste is created in the different processes of textile pro- duction, the amount of which depends on the production scale and consumption level. For this reason, ecological concerns give rise to the search for new solutions to reduce environmental pollution [1-3].
The conventional processing technology for cellulose materials includes desizing, scouring, bleaching, and dyeing of cotton fabrics. These operation sequences consume enormous amounts of energy, water, and chemicals. In terms of cost, this combination of processes is clearly more expensive than a one-step pretreatment [4-9].
Effluents from textile processing plants contain numerous chemical substances. These substances are highly variable because of frequent changes of batch-type textile processing steps. The specific wastewater discharge is around 100-200 m3/ton of fabric, while average pollution is 100 kg chemical oxygen demand (COD)/ton...