Sequential Extrusion and Organosolv Pretreatment for Wheat Straw Valorization

Abstract

Lignocellulosic agricultural side products like wheat straw are widely seen as an important contribution to a sustainable future economy. However, the optimization of biorefinery processes, especially the pretreatment step, is crucial for a economical viable biorefinery. As an attempt to do so, wheat straw was subjected to a Liquid Hot Water (LHW) treatment in an extruder under 2 different conditions followed by an ethanol Organosolv (EOS) treatment in a batch reactor in order to investigate the influence of the extrusion on the extraction yields. Wheat straw extruded at two different extruder settings and non-extruded were included in a central composite experimental design in which the EOS treatment parameter time, temperature and the ratio of wheat straw/solvent were varied. Solid residues and extract were analyzed for lignin, carbohydrate and degradation product composition. The results showed minor influence on the lignin yield, slighty increased carbohydrate yields and increased acetic acid formation.