Non-wood dissolving pulp from Hibiscus rosasinensis for sustainable viscose fibre production

Abstract

This study investigates the potential of Hibiscus rosasinensis stems, a widely cultivated and rapidly growing ornamental plant generating abundant lignocellulosic biomass often discarded as urban and agricultural waste, as a novel non-wood raw material for producing dissolving-grade pulp tailored for regenerated cellulose polymer applications. The bast fibres, rich in cellulose, provide a fast-growing and cost-effective alternative feedstock to conventional wood. Dissolving-grade pulp was obtained via the pre-hydrolysis kraft (PHK) process, combining water-based pre-hydrolysis for hemicellulose removal, kraft cooking for lignin elimination, and subsequent bleaching. The resulting pulp exhibited excellent quality, with α-cellulose 95.2%, hemicellulose 4.8%, residual lignin <0.1%, and intrinsic viscosity of 458 mL g⁻¹. This high-purity pulp was successfully converted into viscose dope through conventional xanthation and regenerated into continuous cellulose polymer fibres via wet spinning. The fibres demonstrated tensile strength, elongation, dyeability, and smooth morphology, confirmed by SEM, comparable to commercial wood-derived viscose rayon, underscoring their suitability for textile applications. By valorising Hibiscus stem waste into functional polymeric fibres, this work establishes a sustainable pathway to reduce dependence on wood resources, mitigate deforestation pressures, and advance circular bioeconomy principles, while harnessing tropical biomass for greener textile industries.