Use of chitosan in mordanting for cotton dyeing with lac dye in supercritical carbon dioxide

Abstract This study explores the use of chitosan as a natural mordant to enhance the dye uptake of cotton fibres dyed with lac dye in scCO 2 . The environmental impact of traditional textile dyeing methods has driven the search for more sustainable alternatives. Supercritical carbon dioxide (scCO 2 ) dyeing presents an innovative solution, eliminating the need for water and reducing chemical waste. However, effective dye fixation on natural fibres like cotton remains a challenge due to the lack of natural affinity between the fibres and non‐polar dyes in the scCO 2 medium. The findings demonstrate that chitosan not only improves the dye fixation but also enhances the colour strength and fastness properties of the dyed cotton. The results highlight the potential of combining chitosan mordanting with scCO 2 dyeing as a sustainable substitute for textile production.