Dyeing properties and colour fastness of wool dyed with indicaxanthin natural dye

Abstract

This research work involves the dyeing of wool with indicaxanthin, a natural dye extracted from fruits of Opuntia ficus-indica. The optimal conditions for dye extraction were to mix 50g of Juice from cactus pears with 100mL of 80% aqueous ethanol as solvent for dye extraction. Liquid chromatography was applied for the separation. Two main dyes were obtained, which were identified as indicaxanthin (75mg per 50g) and betanin (5mg per 50g). The effect of dye bath pH, salt concentration, dyeing time and temperature were studied. The optimal conditions for wool dyeing with indicaxanthin dye were carried out at 70°C for 90min with the pre-treatment of various metal salts as mordant. The colour yields of the dye on the wool were found to be highly dependent of the pH, optimum results being obtained at pH 4. The K/S of wool increased in the order of the dyeing using KAl (SO4)2>MnSO4>CoSO4>FeSO4>none>ZnSO4>CuSO4. Un-mordanted samples have good properties of water and washing fastness. Mordants KAl (SO4)2 and CoSO4 were found to give good light fastness (rating 5).