A new approach for biofinishing of cellulose-containing fabrics using acid cellulases

Abstract

The main objective of this study is to develop a new approach for biofinishing of cellulose-containing fabrics using cellulases under pad-wet batch conditions followed by washing cycle with a high level of mechanical agitation to terminate the enzyme and to remove the weakened fuzz fibers and surface pills, i.e. biopolishing of the fiber's surface. The effect of enzyme dosage, wet-pickup, batching time and temperature as well as type of substrate on the efficiency of enzymatic treatment as well as on the performance and dyeing properties is discussed. Experimental results revealed that padding the used substrates in a bath containing acid-cellulases (20 g/L) and nonionic wetting agent (2 g/L) to a wet-pickup 80% followed by batching at 50 °C for 18 h, and after washing under mechanical action (28 rpm, pH 9, temperature 75 °C, LR 1/20, for 30 min) could upgrade the final properties of the treated substrates especially fabric handle, drapability as well as dyeability with minimal loss in strength. The extent of improvement in the abovementioned properties is determined by the nature of the cellulose-containing fabric. SEM picture clearly shows that the surface of cellulases-treated cotton fabric appear smoother and softer than the untreated one.

Introduction

Enzymes are biological catalysts that accelerate the rate of chemical reaction without themselves undergoing any permanent chemical change. Enzymes have far greater reaction specificity than chemically catalyzed reactions (Jenkins, 2003, Vasconcelos and Paulo, 2006). Enzymatic catalysis takes place at atmospheric pressure, moderate temperature and mild pH conditions, thereby resulting in a reduction in production costs, improving quality and functionality of the textile products as well as increasing the environmental friendliness (Hebeish and Ibrahim, 2007, Jenkins, 2003, Vasconcelos and Paulo, 2006). Enzymes are principally classified and named according to the chemical reaction they catalyze. There are six classes of enzymes namely: oxidoreductases, transeferases, hydrolyases, lyases, isomerases and ligases (Vasconcelos & Paulo, 2006).

Cellulases are the most successful enzymes used in textile wet processing, especially finishing of cellulose-based textiles, with the goal of improved hand and appearance (Diller et al., 1999, Hebeish and Ibrahim, 2007). The efficiency of enzymatic hydrolysis of cellulose using cellulase enzymes is governed by: synergism among different type of cellulases, i.e. endoglucanases that hydrolyze cellulose chains randomly, cellobiohydrolyases that hydrolyze cellobiose from the cellulose chain ends and β-glucosidases that convert cellobiose into glucose, as well as the accessibility of the fiber surface to the enzyme (Tarhan & Sarllslk, 2009). Depilling/cleaning and/or ageing effects are the result of the synergistic action of cellulases and mechanical action simultaneously or sequentially (Paulo & Gubitz, 2003). Improving the dimensional stability of cellulosic fabrics using cellulases under pad-batch conditions had been made before (Cortz, Ellis, & Bishop, 2002).

Several attempts have been made to explore the effect of degree and sequence of mechanical agitation on the efficiency of cellulase treatment (Paulo, 1998, Paulo et al., 1997). Our new investigation is concerned with the technical feasibility of conducting cellulases-treatment of cotton-containing fabrics using the pad-wet batch followed by washing at high level of mechanical action. Physico-mechanical properties, dyeability of cotton with reactive and cotton/polyester blend with reactive/disperse dyes as well as surface morphology were compared.