Three wood species, eucalyptus grandis (E. grandis), southern pine (S. pine), and Norway spruce thermomechanical pulp (N. spruce TMP) were pretreated by dissolution in the ionic liquid (IL) 1-allyl-3methylimidazolium chloride ([AMIM]Cl). The wood was regenerated from the ionic liquid in high yield and the recycling of the ionic liquid was nearly quantitative. The lignin contents and the efficiencies of cellulase enzymatic hydrolyses of the regenerated wood were examined offering an

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... into the IL pretreatment efficiency. The components that remained within the recycled ILs were qualitatively characterized by 31 P NMR spectroscopy. Wood density, pulverization intensity, and the nature of the regeneration nonsolvents were investigated as factors affecting the overall process. An increase in the wood density decreased the efficiency of the pretreatment, whereas extended pulverization periods decreased the yield of the regenerated wood after the IL pretreatment,with more glucose being released during the enzymatic hydrolysis. The yield of wood after IL pretreatment using water as the regeneration nonsolvent was found to be much higher than that of using methanol. As the reuse cycles of IL increased the wood regeneration yield increased, while certain wood components enriched within the recycled IL. The efficiency of cellulase enzymatic hydrolysis on the regenerated wood decreased with increasing reuse cycles of the IL.