Studies on the influence of bacterial collagenase in leather dyeing

Collagenase enzymes are nontoxic and eco-friendly biocatalysts. Dyeing is an important process in the leather industry, which employs many synthetic colorants. Many good dyes suffer from incomplete exhaustion and this causes concern, as the biotreatability of the unexhausted dyes in effluent is normally difficult. Hence in the present study, an attempt has been made to improve the exhaustion of dyes by using bacterial collagenase enzymes as biocatalysts. The effect of process parameters of enzymatic treatment such as pH, temperature and duration on the exhaustion of the dye, levelness of dyeing, shade brightness, dye penetration and color intensity have been studied and the conditions are optimized. Uptake of dye as high as 99% has been observed by the treatment of collagenase. The change in shades due to enzymatic treatment has been quantified by reflectance measurements and compared with the visual assessment data. Scanning electron microscopy analysis showed a well opened-up fibre matrix for the collagenase treated leather. The strength properties are not significantly altered and the bulk properties like softness have been found to be improved by the use of collagenase. (c) 2006 Elsevier Ltd. All rights reserved.