High yield production and separation of furan derivatives from Quercus mongolica by oxalic acid pretreatment

Abstract

230°C, acid concentration: 2-4%, and reaction time: 10 min) to determine the optimal conditions for high yield of furan derivatives and to evaluate the effects of the reaction conditions on the yield of furan derivatives after the 2nd pretreatment. The maximum yield of furan derivatives was 7.66% based on the dry weight of the raw material after pretreatment at 220°C with 2% (w/w) oxalic acid for 10 min. The factor that most influenced the yield of furan derivatives was reaction temperature. To separate furan derivatives from other compounds in the liquid hydrolyzate after two-step pretreatment under optimal conditions, nanofiltration (NF) and solvent extraction were conducted under various operating conditions (NF: filter type (NE90 and DRM), pH, repetition stage) (Solvent extraction: organic solvent (chloroform, butanol, ethyl acetate, propyl acetate), contact time, the hydrolyzate/solvent volume ratio, the number of extraction stage). Solvent extraction showed better efficiency for the separation of furan derivatives than NF. The best yield was obtained with chloroform-extracted furan derivatives (5.97% based on the dry weight of the raw material, corresponding to the recovery rate of 77.26%).