Hydrothermal and organic-chemical treatments of eucalyptus biomass for industrial purposes.

This study aimed to evaluate the promising feasibility of the hydrothermal pre-processing of eucalyptus wood and eucalyptus bark under organosolv and organic acid conditions to produce a highly concentrated cellulose feedstock. For that, particulate samples of both biomasses were heated in water solutions containing from 0 to 50%vol/vol of ethanol and from 0 to 50 mmol.L-1 of oxalic acid at temperatures between 140 and 180 °C. Significant differences on the thermal degradation profiles were observed for both biomasses indicating the partial hydrolysis converted them into a more homogeneous solid fraction with higher contents of cellulose. It was also observed a significant variation of the glycan content from approximately 39 to 76% for wood particles, whereas the variation for bark was from 32 to 50%. In general, the proposed pre-processing route was considered potentially feasible to concentrate the cellulose/glycan contents of eucalyptus biomasses for subsequent industrial utilization.

Resistance of in natura and torrefied wood chips to xylophage fungi.

The diversity of fungi allows for their colonisation in different environments, including wood destined for power generation, with an ability to degrade or hinder its use. Torrefaction or pre-carbonisation, a low oxygenation heat treatment with temperatures between 200 and 300 °C, accumulates carbon and lignin, decreases hygroscopicity, increases energy efficiency and reduces the wood attractiveness to xylophagous microorganisms. This work aimed to study the resistance of Eucalyptus urophylla wood chips, submitted to torrefaction temperatures of 180, 220 and 260 °C for 20 minutes, to xylophagous fungi, according to the ASTM D-2017 method (2005). The white rot fungi Phanerochaete chrysosporium, Pleurotus ostreatus and Trametes versicolor and the brown rot fungus Gloeophyllum trabeum were used. After 12 weeks of exposure, the mass losses of wood samples in natura and torrified at 180 °C attacked by Pleurotus ostreatus and Trametes versicolor was higher. Torrefaction increased the resistance to fungi; the treatment at 260 °C was the most efficient with lower mass losses caused by fungi attacks and, consequently, greater resistance to the fungi tested.