Fig. 4

Switchgrass (SWG) deacetylation mass closure of glucan (top left), xylan (top right), lignin (bottom left), and acetyl (bottom right). Lignin conversion yield to black liquor was likely overestimated due to the lack of an accurate quantifying method. Acetyl conversion yield was high due to under quantifying acetyl in the raw feedstock. The acetyl is nearly all removed from the insoluble solids fraction. Lignin is removed more when the concentration of sodium hydroxide is increased. Lignin was removed more efficiently with switchgrass than poplar but not as well as with corn stover. The glucan remained with the insoluble solids fraction with the xylan increasing as the concentration of sodium hydroxide increased. X/Y/Z represents NaOH conc (g/kg)/residence time (min)/disc-refining gap (in.)