Chemical characterization of Wood and Bark biomass of the invasive species of Tree-of-heaven (Ailanthus altissima (Mill.) Swingle), focusing on its chemical composition horizontal variability assessment

Abstract

ABSTRACT Aim of this study is to evaluate the potential of a rational utilization of wood and bark of the invasive species of tree-of-heaven (Ailanthus altissima (Mill.) Swingle), through their thorough chemical characterization. Extractives, celluloses, hemicelluloses, lignin, and ash contents of wood and bark material of different tree sections were examined, using wet chemical analyses/extractions. The horizontal variability of the chemical composition of the stems from pith to cambium was investigated, as well as the differences between early- and late-wood, different annual rings, sapwood and heartwood, and differences between wood and bark. The material’s equilibrium moisture content, density, pH, colour, and calorific value were also determined. Bark material presented higher extractives, slightly higher lignin, much higher ash, and slightly lower holocellulose content than wood. As the tree-age increases, the wood and bark present lower lignin, but a linear increase of holocellulose and extractives. The heartwood demonstrated more extractives, lignin and ash, and less holocellulose than sapwood. Very low ash contents and high calorific values constitute features highly crucial for its utilization in solid biofuel production. The optimum harvesting time for the highest possible utilization of extractives and holocellulose is after the 21st year, while for lignin after the 5th year.