Production and characterization of lignocellulosic fractions from sisal waste

Abstract An integrated fractionation process, UV-catalyzed hydrogen peroxide pretreatment (UHP) with subsequent alkali and acidic ethanol extraction, was developed to consecutively recover cellulose, hemicellulose, lignin and pretreated liquid fractions from sisal waste. These fractions serve as a viable source of high-value industrial chemicals. Delignification rate reached approximately 80 % under the UHP pretreatment with 0.1 mL/g H2O2 for 6 h. The pretreated sisal waste was further fractionated into four parts, cellulose (35.5 g/100 g sisal waste), xylan-rich hemicellulose (12.5 g/100 g sisal waste), acid-insoluble lignin (5.7 g/100 g sisal waste) and the liquid fraction (21.0 g/100 g sisal waste). The cellulose fraction was in high purity with increased crystalline index of 51.4 %, and the hemicellulose fraction was rich in xylan. The lignin fraction had the GSH-type structure with some ferulic acid residues bound mainly via β-O-4 linkages. The liquid fraction had a high content of phenolic compounds (16.26∼41.88 mg GAE/L) with strong antioxidant activities, 11.16∼18.48 μmol TE/L reducing power, 66.78∼82.84 μmol TE/L hydroxyl radical scavenging and 14.83∼46.67 μmol TE/L ABTS radical scavenging.