Aqueous two-phase systems applied to the extraction of syringaldehyde and vanillin from eucalyptus wood residues

This work examines the recovery of phenolic compounds through the autohydrolysis of eucalyptus wood residues. The hydrolysis of pin chips was carried out using hot water under different conditions. This treatment was capable of extracting xylosaccharides, phenols, furfural (FUR), hydroxymethylfurfural (HMF) and acetic acid (AAc). The highest phenolic contents were attained at 160 °C and 110 minutes, where total phenolic compounds (TPC) reached 1.33% gallic acid equivalent (GAE) and syringaldehyde (SA) and vanillin (VAN) were at 0.01% each, in pin chips dry basis (d.b.). The capacity to extract phenolic compounds from pin chip hydrolysate through aqueous two-phase systems (ATPS) based on PEG 2000 and sodium citrate was demonstrated. High extraction efficiency was obtained (99.8% for the TPC, 82.3% for the SA, 94.9% for the VAN, 89.3% for the FUR and 70.9% for the AAc). The recovery of sugars in the bottom phase was 58.4%.