Influence of Enzymatic Pretreatment on the Colours of Bleached and Dyed Flax Fibres

SUMMARY

In this paper the effect of enzymatic bioscouring on the bleaching and dyeing of flax fibres was studied in comparison with conventional alkaline scouring. Enzymatic bioscouring was performed with a commercial multi-enzyme system consisting of pectinases, hemicellulases and cellulases. The enzyme and alkaline scoured flax fibres were subsequently oxidatively bleached with hydrogen peroxide and dyed with direct dye C.I. Direct Red 80 under the same conditions. The efficiency of both the scouring and bleaching processes was evaluated by weight loss and the whiteness of the bleached samples was determined according to CIE formula. The exhaustion profile of the used dye was followed on-line during the dyeing process using absorbance measurement. The colours of bleached and dyed samples were evaluated using CIELAB colour values. The residual pretreatment and dyeing baths were ecologically analysed with COD, TOC and BOD₅. The obtained results indicate that enzymatic scouring provides a lower weight loss, a higher degree of whiteness, comparable dyeing properties and is more environmentally friendly.

Key Words:

• Flax fibres
• enzyme pretreatment
• alkaline scouring
• bleaching
• dyeing
• colorimetry
• ecology