Valorisation of Napier grass through fibre extraction and coloration by natural dye from Rubia tinctorum

Abstract

Agricultural biomass is a well-known renewable resource with a strong possibility of recycling. The current work focuses on extracting, preparing and colouring Napier grass fibre (NGF) with a colourant extracted from Rubia tinctorum (RT) (which is generally known as madder). NGF that had been water-retted was alkaline scoured and bleached using hydrogen peroxide to increase the material's whiteness index and water absorption capacity without degrading its breaking strength. After being mordanted with tannic acid, the bleached NGF was coloured with an aqueous extract of the colourant extracted from RT. The Box–Behnken response surface methodology design model was employed to optimise the dyeing concentration, temperature and time. The dyed fibre showed good colour strength (K/S) and adequate wash, rub and light fastness. Adopting the findings from the current study would increase the efficient utilisation of biomass for use in textiles, which is unnecessarily wasted.