Eco-friendly scouring of cotton knit fabrics with enzyme and soapnut: An alternative to conventional NaOH and synthetic surfactant based scouring

Abstract

Eye-catching, aesthetic fashions often suppress its untold dark story of unsustainable processing including hazardous wet treatment. Considering the risks imposed by conventional cotton scouring and following the trend of scouring with enzymes, this study was undertaken to evaluate the bioscouring of cotton knit fabric involving saponin-enriched soapnut as a natural surfactant, applied from a bath requiring a few chemicals and gentle processing conditions, contributing to the eco-friendliness. The proposed application was compared to synthetic detergent engaged enzymatic scouring as well as the classic scouring with Sodium hydroxide. A cellulolytic pectate lyase enzyme (0.5%–0.8% o.w.f) was applied at 55 °C for 60 min at pH 5–5.5 with varying surfactant concentrations. A low concentration of soapnut extract (1 g/L to 2 g/L) was found sufficient to assist in the removal of non-cellulosic impurities from the cotton fabric after bioscouring with 0.5% o.w.f. enzyme, leading to good hydrophilicity indicated by an average wetting time of 4.86 s at the expense of 3.1%–3.8% weight loss. The scoured fabrics were further dyed with 1% o.w.f. reactive dye to observe the dyeing performance. The treated samples were characterized in terms of weight loss, wettability, bursting strength, whiteness index, and color value. The proposed application confronted level dyeing and the ratings for color fastness to washing and rubbing were 4–5 for all of the samples scoured enzymatically with soapnut. The study was also statistically analyzed and concluded.