Effect of hydrothermal pretreated bamboo lignin on cellulose saccharification for bioethanol production

Abstract

To obtain biofuels or small molecule chemicals from biomass, cellulose is a challenge and enzymatic cellulase is normally required. In this study, Pleioblastus amarus (P. amarus) with high abundance and fast growth speed distributed in the southwest of China, was subjected to the hydrothermal pretreatment at different temperatures. The syringyl/guaiacyl (S/G) ratio of the hydrothermally pretreated lignins (HPLs) was decreased from 0.91 to 0.44, and the hydrophobicity of HPLs was increased from 1.25 to 10.90 L/g when the pretreatment temperature was increased from 160 to 200 °C. In addition, the higher content of phenolic hydroxyl groups in lignin at high pretreatment severity also contributed to the higher non-productive binding between lignin and cellulase. The Langmuir isotherm suggested that a higher treatment temperature led to the increase of binding affinity between HPL and cellulase. Finally, the uses of HPL160, HPL180, HPL200, when pretreated at 160, 180, and 200 °C, respectively, had a glucose yield of 52.7 %, 34.9 % and 32.6 %, respectively, which was lower than that of Avicel alone in the enzymatic saccharification process. This study provides a significant selection and control of hydrothermal pretreatment severity for achieving a high cellulose saccharification yield for bioethanol production.