Simulation and optimization of barley straw organosolv pretreatment

In this study, acid catalysed acetone organosolv pre-treatment of barley straw was investigated and the optimal conditions were determined using two different approaches: a new combined severity factor (CSF) and the response surface methodology (RSM) based on Box-Behnken experimental design. The key variables selected were temperature (140-180 °C), residence time (0-40 min) and sulphuric acid concentration (10-35 mol/m3). Useful information was derived from both approaches, although the RSM fit better to the experimental results. The sulphuric acid concentration was the most important factor, it influenced not only the barley straw fractionation but also the enzymatic hydrolysis of the cellulosic residues. The optimal conditions for maximising the cellulose-to-glucose conversion (75.4%) and total xylose recovery in the liquid phase (66.7%) were a residence time of 20 min at 140 °C and 35 mol/m3 of sulphuric acid.