Eco-friendly and sustainable application of gardenia yellow extraction as natural dye source for dyeing and bio-functional finishing of cotton fabric

Based on the trend of low-carbon emissions and environmentally friendly development, this paper extracted natural dye from gardenia for cellulose fiber dyeing and endowed them with UV resistance and antibacterial properties. And more attention was paid to the dye structure of the gardenia yellow dye and its alkali-hydrolyzed gardenia yellow dye on dye uptake, UV–visible absorption characteristic peak as well as functional finishing. The main dye components of gardenia yellow dye and its alkali-hydrolyzed gardenia yellow dye were measured by the UV–visible and LC–MS spectrum. The crocin, which was the main dye components in the gardenia yellow dye, presented higher maximum absorption wavelength and darker colors compared with alkali-hydrolyzed gardenia yellow dye, which the main dye components was croceic acid. The cotton fabrics dyed with gardenia yellow dye or alkali-hydrolyzed gardenia yellow dye all indicated well dyeing performacne and functional characteristics such as antioxidant activity, UPF values and antibacterial property against Staphylococcus aureus and Escherichia coli . The main reason for different in the dyeing and functional performance of cotton fabrics dyed with gardenia yellow dye or its alkali-hydrolyzed dye were the removing gentiobiose molecules under alkali treatment, which changed the conjugate systems, ionization capacity, and polyphenols and flavonoids content. And the study examines the dyeing kinetics, adsorption isotherm, and thermodynamics of gardenia yellow dye and its alkali-hydrolyzed gardenia yellow dye on the cationic cotton. It is expected that achievement of this research provide guide to the value adding utilization of agricultural by-products from crop industries and view to investigate the effect of dye composition on the dyeing and functional performance. Graphical Abstract