Optimization and Modification of Enzymatic Desizing of Starch-Size

Abstract

A comprehensive study was carried out to attempt to find out the proper and optimal conditions for attaining a higher extent of enzymatic desizing of starch size, modifying the desizing formulations via incorporation of H₂O₂ or a neutral cellulase enzyme along with α-amylases, and evaluating the impact of these modified formulations on the performance properties of the desized cotton fabrics. Several factors affecting the starch-size removal were studied and are discussed in this article. The results detailed in this article indicate that: (a) the effectiveness of enzymatic desizing can be enhanced by raising the desizing temperature up to 70°C; prolonging the desizing time up to 60 min: adding CaCl₂·2H₂O, as an enzyme-stabilizer up to 0.5 g/L; increasing the material-to-liquor ratio up to 20:1; increasing the Aquazym® 240-L dosage up to 6 g/L; treating at pH 7; and/or increasing the agitation rate up to 40 rpm, irrespective of the used substrate; (b) the higher the extent of the size removal, the lower the retained strength of the desized fabric; (c) the extent of enzymatic desizing is governed by the type of wetting agent, i.e., nonionic > nonionic/anionic > anionic > none, as well the nature and activity of the α-amylase enzyme, i.e., Aquazym® Ultra 250L > Aquazym® 240L > none; (d) including H₂O₂ (4 mL/L–35%) along with Aquazym® 240L (6 g/L) improves the extent of the desizing, the degree of whiteness, as well as the dyeability with reactive dyes; and (e) incorporation of a neutral cellulase enzyme (2% owf, Denimax® 302S) along with Aquazym® 240L (6 g/L) gives rise to higher weight loss, better wettability, lower stiffness, and higher dye uptake along with a marginal improvement in the extent of desizing.