A synergistic combination of shrimp shell derived chitosan polysaccharide with Citrus sinensis peel extract for the development of colourful and bioactive cellulosic textile.

Green finishing formulations have established an important place in textile dyeing and finishing industry. The use of plant extracts along with chemical metallic mordants is reported to increase colour values and improve fastness properties. However, metal salts as mordants constantly pose environmental and human health risks. The purpose of this work is to examine and extend the knowledge of natural dyeing technology considering the use of biological macromolecule chitosan (CS) to increase dye uptake, fastness and impart functional properties. The cotton was pre-coated with chitosan using pad-dry method and optimal chitosan concentrations were selected by evaluating the colour spectrometry data in term of CIEL*a*b* values. The chemical nature of the extract was characterized by UV-Vis, Fourier-transform infrared spectroscopy (FT-IR) and Thermogravimetric analysis (TGA) whereas dyed samples were analysed by Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) with mapping analysis, FT-IR, and TGA. Results showed that the aqueous extract of Citrus sinensis peel yielded interestingly shades all lying in yellow- red quadrant of CIELa*b* colour space with acceptable grades of wash and dry-wet fastness properties. This study reveals important information to understand synergism between two natural products in imparting semi durable antioxidant and antibacterial activity against E. coli and S. aureus, and thus offers full potential to be used in natural dyeing technology.