Integrated valorization of eucalyptus sawdust within a biorefinery approach by autohydrolysis and organosolv pretreatments

Abstract

Eucalyptus sawdust is a residue from the pulp industry, currently used for energy production. Organosolv and autohydrolysis pretreatments for integrated valorization of this residue within a biorefinery approach was investigated. Organosolv pretreatment was used for selectively extract lignin, and autohydrolysis pretreatment was effective for hemicellulose solubilization. Glucose production of 33.7 g/100 geucalyptus was achieved after organosolv pretreatment, while dissolving 6.4 g/100 geucalyptus of xylan-derived sugars and recovering 10.3 g/100 geucalyptus of lignin after precipitation. After autohydrolysis pretreatment, glucose production of 32.3 g/100 geucalyptus was reached, while 7.5 g/100 geucalyptus of xylan-derived sugars and 2.7 g/100 geucalyptus of acetyl groups were effectively dissolved in a separate liquid stream. Non-ionic surfactant (PEG 6000) was used to enhance cellulose hydrolysis. Integration of a suitable pretreatment and enzymatic hydrolysis steps was shown to be a feasible strategy for the co-production of different value-added products (lignin, xylose, xylo-oligomers, acetic acid), towards a cost-effective eucalyptus biorefinery.