Low Temperature Bleaching of Jute Using Peracetic Acid: A Novel Process

Abstract

Jute, a natural golden fibre, is renewable and widely available and mostly used for the packaging of agricultural crops and commodities in the form of sack bag. However, over a period of time it has secured its own market in the field of home textiles and other lifestyle products due to its ethnic colour, good strength and biodegradable properties. Recently, jute has also been used in apparel products, particularly meant for outer and winter garments. Bleaching of jute has thus become an essential operation for making a white glossy fabric, that is, the base material to be used for subsequent coloration. The conventional hot hydrogen peroxide bleaching process produces good white fibre with a high loss in tensile strength. The present peracetic acid bleaching of scoured jute produces a satisfactory whiteness index of 65.8–77.7 with minimum loss of bundle strength. The peracetic acid bleached jute fibre could retain 85% of its bundle strength, when the bleaching was carried out at 70°C with 20 g/l peracetic acid for 120 min. A satisfactory whiteness index of 77 (Hunter scale) can be achieved incurring a low weight loss of <4.2 using the optimized recipe. The peracetic acid bleaching process may be considered as energy efficient and environment friendly, as the process is carried out at a near neutral pH of 7.5–8 and lower temperature of 50–70°C, in comparison to the 85–90°C and pH level of 11–11.5 (highly alkaline) normally used in hydrogen peroxide bleaching. The changes in physical, morphological and chemical properties after the peracetic acid bleaching of jute at optimized conditions were evaluated in detail.