49 / 2021-05-30 11:54:01

Cellulose nanofibers preparation combined with bioethanol production from fermented sweet sorghum bagasse

Cellulose nanofibers;,Bioethanol;,Sweet sorghum;,Alkaline distillation;,High pressure homogenization;

Cellulose nanofibers (CNFs) are promising green scaffolds for broad application prospect in paper making, food, electronics and medicine industries, etc., and have attracted considerable attention worldwide.. In order to make CNFs cost-competitive, we combined CNFs preparation with ethanol production from sweet sorghum stalks via advanced solid state fermentation (ASSF). Solid-state distillation is a necessary step for ethanol extracting from fermented sweet sorghum bagasse (FSSB), alkaline can be added during distillation to remove lignin for saving energy to open “structure” of lignocellulose in conventional CNFs production.

In this study, the effects of different sodium hydroxide on the quality of distilled ethanol and the pretreatment of lignocellulose, subsequent high pressure homogenization for preparing CNFs from pretreated FSSB, the characteristics of pretreated FSSB and the performance of CNFs were investigated. The results showed that only trace sodium hydroxide was found in the distilled ethanol, which could be completely removed in the subsequent rectification process of fuel ethanol production..  The crystallinity of alkali treated FSSB was increased and the fiber surface was smoother during the alkaline distillation demonstrated by XRD and SEM results. The transmission electron microscope shows that the obtained CNFs were interconnected with fiber bundles, which formed entangled networks in the high alkaline treated suspension. Thermos gravimetric analysis results indicated that the degradation temperature of the CNFs can be increased effectively compared with FSSB.

The alkaline distillation of FSSB integrating high pressure homogenization can produce high quality CNFs without affecting ethanol extraction. Importantly, there is no black liquor produced in the distillation process. The black liquor produced during alkaline FSSB washing is much less than conventional pulping process, which is convenient to recover alkali and lignin. The process of CNFs preparation combined with bioethanol production is environment-friendly, energy-efficient and water saving. It is beneficial to the industrialization development of CNFs by using it in the commercial solid-state bioethanol production.