Environmentally friendly delignification of flax using hydrogen peroxide: influence of delignification on the fibre structure and property

This study explores an environmentally friendly and efficient technique for delignifying flax fibres using hydrogen peroxide. As a widely used chemical in the pulp and paper industry, hydrogen peroxide offers simplicity, safety, and minimal environmental impact. The delignification process achieved a significant reduction in lignin content, from approximately 2% to 0.3%, after 20 min of treatment at 70 °C. This reduction enabled the splitting of flax fibre bundles from an initial diameter of around 70 µm to approximately 20 µm, while preserving the fibres' chemical structure and mechanical performance. Higher hysteresis in moisture sorption and desorption in the region above 60% relative humidity indicates increased softening of the delignified fibre. The process also improved fibre fineness and homogeneity, making flax fibres more suitable for textile applications. By addressing the challenges of flax fibre processability, this technique positions flax as a sustainable alternative to cotton, with potential applications in textiles and other industries. The findings highlight the potential of hydrogen peroxide-based delignification to enhance the utilization of natural bast fibres while reducing environmental impact, thus broadening their applications.