Covalent modification of enzymes for textile processes
Akçapınar, Günseli Bayram (2005) Covalent modification of enzymes for textile processes. [Thesis]
Wide range of application of enzymes allowed their use in many textile processes such as biopolishing, desizing and bleaching. Cellulase enzymes have been used for the biopolishing of cellulosic fibers and fabrics. In this work the focus was on two seperate applications of modified enzymes in textile processing, one is to retain strength of viscos during pilling process and the second is to combine desizing and the bleaching processes of the fabric. Cellulases are used to prevent pilling on the surface of the viscose fabric but they couse a loss in the tensile strength of the viscose fabric. Commercial celluloses were crosslinked using different parameters in an attempt to ameliorate the loss of tensile strength and to improve enzyme properties. Native and modified enzymes were characterized and their activities against CMC and their effects on the properties of viscose (such as pilling, bursting strength) fabric were determined. Effects of mechanical agitation and surfactants were examined. Crosslinking of cellulase was found to prevent the loss of strength due to the fact that larger enzyme complexes formed by crosslinking were minly resticted to the fabric surface. Enzymes are replacing the use of harsh chemicals in many of the textile processes such as desizind and bleaching and immobilizations of these enzymes on solid supports allow their recycling. Enzymatically produced peroxide is used for bleaching of the cotton fabrics. Commercial Glucosse oxidase (GOx) enzyme was immobilized on different supports such as alumina, silica, Sepharose 4B and crosslinked enzyme aggragates of GOx were prepared. Their efficiencies against glucose substrate for the production of peroxide were analyzed. Moreover, the starch size of the cotton fabric is hydrolized into glucose by the action of amyloglucosidase and this liquor was also used to produce peroxide. The activities of immobilized enzymes and CLEAs against desizing liquor and the whiteness values of the cotton fabrics after bleaching were examined. The whiteness values reached with immobilized enzyme are not appropriate for white textile but is sufficient for further dyeing processe. Combination of desizing and bleaching in a single bath and recycling of the immobilized enzyme is an environmently friendly alternative.
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