Dyeing with enzymatically treated bleaching effluents

Abstract

Hydrogen peroxide is commonly used bleaching agent for textiles. Dyeing after bleaching requires repeatedly rinsing the textile material to remove any residue of peroxide that might be harmful to the dyes either in solution or on the fabric. 1 , 2 Even this washing process cannot guarantee the complete removal of the peroxide. Contemporary biotechnology offers the opportunity to reduce the large water consumption required for washing by the use of catalases for peroxide decomposition. Catalase is known for its ability to catalyze the conversion of hydrogen peroxide to water and gaseous oxygen. 3 , 4 There are two possible approaches for applying this enzyme prior to dyeing-draining off the bleach bath and refilling it with water containing the enzyme or adding the enzyme directly to the bleaching liquor and then reusing it for dyeing. The first approach was adopted in the textile industry and all catalase-based commercial products have been applied in that way. 5 The second approach represents a new, unconventional dyeing technique; e.g., dyeing in the bleach bath, which may ensure efficient reduction of water and energy consumption.