Analytical methodology for biomass pretreatment. Part 2: Characterization of the filtrates and cumulative product distribution as a function of treatment severity

Abstract

Populus deltoides was pretreated using an aqueous/steam thermo-mechanical process in which shear forces were applied to medium consistency slurries by rapid passage through homogenizing valves. As a consequence of the treatment the biomass material was partially solubilized. In a previous paper (Bouchard, J., Nguyen, T. S., Chornet, E. & Overend, R. P. (1990). Analytical methodology for biomass pretreatment. Part 1: Solid residues. Biomass, 23 (4) 243–261), the characterization of the solids was discussed. The present paper concerns the characterization of the water-soluble fractions by standard, thermal (DSC) and spectroscopic (DRIFT) methods. The results are discussed in terms of the effect of the severity of the treatment on the chemical structure of the soluble wood polymers. A comparative evaluation between steam explosion and aqueous processes on the importance of the autohydrolysis concept and the role played by acetic acid is presented.