Fractionation of rapeseed straw by hydrothermal/dilute acid pretreatment combined with alkali post-treatment for improving its enzymatic hydrolysis

- Rapeseed was treated by hydrothermal/dilute-acid at different temperature ranges.
- The effect of temperature on glucose yield and structure was evaluated.
- High temperature resulted in substantial changes of rapeseed straw structure.
- Delignification with pretreatments greatly reduced the biomass recalcitrance.
- A two-step treatment efficiently separated cellulose, hemicelluloses and lignin.

The aim of the research was to evaluate the effect of combined treatments on fermentable sugar production from rapeseed straw. An optimum condition was found to be the combination of hydrothermal pretreatment at 180 °C for 45 min and post-treatment by 2% NaOH at 100 °C for 2 h, which was based on the quantity of monosaccharides released during enzymatic hydrolysis. As compared with the raw material without treatment, the combination of hydrothermal pretreatment and alkali post-treatment resulted in a significant increase of the saccharification rate by 5.9 times. This process potentially turned rapeseed straw into value added products in accordance with the biorefinery concept.