Effect of chitosan biological macromolecule on colorimetric analysis and radical scavenging activity of linen using...

Over the past few years, the application of green and sustainable biological macromolecules to replace petrochemical based agents for functional modification of textiles is gaining popularity worldwide. With a view to develop the green finishing process for linen fabrics, the present study was designed to evaluate colorimetric analysis and radical-scavenging activity of pineapple peel dyeing on linen pre-treated with chitosan polysaccharide under optimum natural dyeing conditions. Linen fabric was treated with different concentrations of chitosan using a conventional pad-dry-cure method. UV-vis was used to observe optical property of pineapple dye, while as Scanning electron microscopy, EDX analysis along with mapping images, Fourier transform infra-red spectroscopy, X ray diffraction, and thermal analysis of coated samples revealed the fixation of the chitosan onto the fabric's surface. Direct natural dyeing was compared with those obtained with chitosan coating. It was found that the pre-treatment of chitosan provided a significant improvement in dye uptake and CIELa*b* values. Furthermore, the linen fabric treated with chitosan in conjugation with pineapple natural dye showed excellent radical-scavenging properties compared to the control dyed linen. The depth of shade as well as radical-scavenging activity was found greatly dependent on chitosan concentration. The radical scavenging property was quite durable and was retained through 5 washing cycles. The analysis of the dyeing mechanism suggested that chitosan reacts with hydroxyl groups in cellulose and functional sites in natural dye via inter-ionic attractions.