Abstract

Instead of using metallic-salt-based chemical mordants for natural dyeing, eco-friendly newer approaches /routes of cotton fabrics were bio-cationised with deoiled waste soyabean seeds for salt-free dyeing of cotton with anionic catechu (Acacia catechu) dye with or without additional use of natural ore-based Fitkari or potash alum (K-alum) to enhance its dyeability and overall colour fastness. It is observed from this study that bio-cationization with acid-hydrolysed deoiled waste soya bean seed extract is found to be very effective with the addition of K-alum as an additional mineral ore-based natural mordant. In the present part of the work, optimum dyeing conditions were standardised for eco-friendly salt-free dyeing of soyabased bio-cationized cotton (SB-Cotton). The standardized optimum conditions/parameters were found as (i) optimum concentration of waste soya seed extract: 10% owf, (ii) concentration of natural potash alum pre mordants: 10% owf, (iii) Optimum concentration of dye (anionic tannate based catechu natural dye): 30% aqueous extract ( on the oven-dry mass of catechu powder), (iv) optimum material: liquor ratio: 1:20,(v) optimum pH of dye liquor: 4, (vi) optimum temperature of dyeing: 70 °C, (vii) Optimum time of dyeing: 60 min and Salt concentration: Nil ( i.e without any salt (for this eco-friendly salt free dyeing ).

Keywords:Acacia catechu; Bio-Cationization; Bio-mordanting; Catechu natural dye; Cotton; Colour fastness; Colour strength; Standardisation of dyeing conditions