Application of enzymes in wool dyeing

The application of enzymes in wool dyeing process is an important goal of research in order to reduce the environmental impact and costs of this fundamental finishing process of wool. This work has focused on the possibility of reducing the temperature of conventional dyeing, using an enzymatic pretreatment. Proteolytic enzymes belonging to hydrolase class were used to improve the diffusion of the dye into the fibers at lower temperatures than traditional method, with or without auxiliary agents. Exhaustion curves of the dye bath apparent activation energy values and absorption rate constants were determined. The protection of wool fiber properties during the treatments has been investigated. In order to evaluate a possible fiber damage, the dyed samples were observed by scanning electron microscopy (SEM) and at the same time the loss of tensile strength and elongation were determined. The attack degree of the enzyme was controlled by SDS-Page analysis. In addition, colour fastness to domestic laundering, artificial light, rubbing and perspiration were carried out. These are very important parameters related to the quality of the material produced. The results of this study show the possibility, thanks to the use of the enzyme investigated, to obtain an homogeneous and strenght dyeing, on fibers maintaining the same mechanical properties, already working at 85°C, a temperature process clearly under 98°C currently used in industry.