Investigation and optimization of Supercritical CO 2 dyeing of cotton with Laccaic acid for sustainable textile production with improved fastness

Supercritical carbon dioxide (scCO2) was employed as a sustainable and ecological means for cotton dyeing using Laccaic acid also known as lac dye. Cotton was pre-treated with polyethylene glycol 600 (PEG) and dyed with benzamide which resulted in a considerable increase in colour strength, fastness properties, and dye adsorption. Colour strength was increased by raising dye intensity from 1% to 3% o.w.f (on weight of fibre) which was evaluated using color strength (K/S) measurements. The optimal K/S of cotton was obtained at 110 °C, 20 MPa and 3h with a dye intensity of 3% o.w.f. Dyeing results implied that pretreated cotton had improved K/S and better fastness with benzamide. The breaking force of dyed cotton was studied. The system parameters affecting the dyeing properties, including the effect of dye auxiliaries, dye concentration, temperature, pressure, and dyeing time were also examined.