Integrated utilization of the main components of Hesperaloe funifera

Abstract

This work aims at the characterization and the biorefinery of Hesperaloe funifera by means of the use of its three main components: separating hemicellulose by hydrothermal treatments; cellulose pulp by various pulping processes (soda, soda–anthraquinone, ethanolamine, ethyleneglycol, diethanolamine and diethyleneglycol); and exploitation of pulping liquor, rich in lignin, by pyrolysis and gasification processes. The contents in lignin, α-cellulose, holocellulose, hemicellulose, ethanol–benzene extractives, hot water solubles, 1% NaOH solubles and ash of H. funifera were found to be 7.3%, 40.9%, 76.5%, 35.6%, 4.0%, 13.5%, 29.5% and 5.9%, respectively. The mean fibre length, 4.19 mm, exceeds those for some non-wood materials. By using sulfuric acid in the hydrothermal treatment (170 °C, 0, 20 min after reaching operating temperature, 8 liquid/solid ratio, and 0.3% sulfuric acid), gives a liquid fraction containing 4.62% of glucose, 10.56% of xylose, 1.28% of arabinose, and a solid fraction with a solid yield of 57.0%. The best pulp of Hesperaloe pulp was obtained by cooking with 10% NaOH and 1% anthraquinone at 155 °C for 30 min, exhibited good values of yield (48.3%), viscosity (737 mL/g), Kappa number (15.2), tensile index (83.6 Nm/g), stretch (3.8%), burst index (7.34 kN/g) and tear index (3.20 mNm 2/g). Moreover, the soda–anthraquinone pulps of raw material are better than the pulps from solid fraction of hydrothermal treatments. Finally, acidification (pH 6) of soda–anthraquinone pulping liquor was carried out to separate lignin-rich solids, by which pyrolysis gave a gas containing 1.13% H 2, 31.79% CO and 1.86% CH 4 by weight. Gasification of the same sample provided a gas containing 0.18% H 2, 24.50% CO and 17.75% CH 4.