Fractionation of willow biomass for combined production of fibres, chemicals and energy-structure and chemical composition of bark

摘要

1. Willow inner bark is formed of bundles of thick-walled scierenchyma fibres and surrounding tissue of thin-walled parenchyma cells. The sclerenchyma fibres are long, their aspect ratio is high, and the average microfibril angle is close to zero. 2. The extractive and ash contents of the willow inner bark are high. 3. Ca. 20% of the dry mass of willow bark could be extracted simply by hot water (≥ 80 °C, 20 min). Triandrin (6.6 % HWE, potential high medical value), plcein (7.6% HWE) and catechin (2.8 % HWE) were identified as the main components besides glucose and fructose. 4. A fractionation process for valorization of fast-growing willow biomass is envisioned: production of extractives and fibres from the bark, and sugars and lignin from the debarked wood.