Influence of Direct and Reactive Dyes on the Enzymatic Hydrolysis of Cotton

Abstract

Cotton fabric is subjected to enzymatic hydrolysis with cellulases before and after dyeing. The effects of direct dyes of increasing molecular size on the rate of the en zymatic hydrolysis reaction are investigated, along with mono- and bifunctional reac tive dyes with different functional groups. All reactive dyes studied and especially bifunctional reactive dyes, have a decelerating influence on enzymatic attack. The effect of the direct dyes depends strongly on the enzymatic treatment duration. Moisture regain values of enzyme treated fabric suggest a transient state of somewhat increased disorder of the cellulose structure at a specific stage of hydrolysis, which is alleviated by longer incubation times. At this stage, direct dyed fabric shows a hydrolysis rate approximately equal to or slightly higher than undyed fabric.