Fractionation and Biotransformation of Lignocelluloses-Based Wastes for Bioethanol, Xylose and Vanillin Production

In this study combined NaOH/H2SO4 pretreatment of lignocellulosic biomasses (palm fronds, eucalyptus chips, almond shells and Aleppo pine cones) were used to separate hemicellulose and lignin and improve enzymatic digestibility of cellulose. The recovered celluloses were hydrolyzed using Cellic C-Tec2 or Cellic H-Tech2. The optimal saccharification yields 95.8, 94, 73.3 and 80.5% were obtained from the recovered celluloses of palm fronds, eucalyptus chips, almond shells and Aleppo pine cones respectively using Cellic H-Tec2. The highest ethanol yield [42.6 (±0.8 g) ethanol per 100 g glucose] was obtained from pretreated palm fronds which were hydrolyzed with Cellic H-Tech2. Hemicellulosic fractions obtained after ethanol precipitation were hydrolyzed using diluted acid (10%). These fractions were essentially composed of 38% xylose. Lignins, isolated from lignocellulosic biomasses were analyzed by FT-IR, the major bands characterize the aliphatic and phenolic hydroxyl groups as well as the ketones and aliphatic esters groups. This aromatic character makes it possible to use these lignins as precursor for vanillin production. The highest vanillin production of 162 µg mL−1 was obtained after 96 h of Aleppo pine cone lignin biotransformation by isolated white rot fungi.