Dyeability of Chitosan-pretreated Cotton Fabrics with Gardenia-based Colorant Mixtures

Chitosan pretreatment was very effective in increasing the dyeability of cotton fabrics with gardenia blue and red colorants, when compared to that with gardenia yellow, presumably because of increased electrostatic interactions between the cationized cotton and the anionic dyes containing genipin moiety under alkaline conditions. The colorant mixtures of gardenia yellow, blue, and red dyes in a dyebath can be used to dye the pretreated cotton under pH 9, which can effectively produce various hues of green, brown, and purple. The color fastness properties of the dyed fabrics substantially increased when cellulose was cross-linked with citric acid after aluminum alum mordanting of the dyed fabrics. The cotton fabrics dyed with gardenia red showed excellent antimicrobial activity against both Staphylococcus aureus and Klebsiella pneumoniae without post treatments.