Effects of combination of steam explosion and microwave irradiation (SE–MI) pretreatment on enzymatic hydrolysis, sugar yields and structural properties of corn stover

A novel process named combination of steam explosion and microwave irradiation (SE–MI) method was investigated and compared with steam explosion (SE) method for pretreating corn stover under 540 W microwave power and 3 min microwave irradiation time. Both of the two pretreatment methods were operated at 170–210 °C for 3–15 min. Results showed that compared to SE process, SE–MI process enhanced the enzymatic hydrolysis yields of both glucose and xylose, and slightly increased the total sugar yield. The maximum glucose yield, xylose yield and total sugar yield of the process were 57.4%, 17.8% and 75.2% (corresponding to 100% maximum total sugar in feedstock), respectively, obtained at 200 °C for 5 min. SE–MI pretreatment showed attractive advantage in inhibiting the increase of biomass crystallinity. The crystallinity following SE–MI pretreatment was 19% lower than that following SE pretreatment at 190 °C for 5 min.

► A novel SE–MI pretreatment process was proposed and compared to SE process.
► SE–MI process greatly improved the enzymatic hydrolysis yield compared to SE process.
► SE–MI process slightly increased the total sugar yield compared to SE process.
► The maximum glucose yield, xylose yield and total sugar yield of the process were 57.4%, 17.8% and 75.2%, respectively, obtained at 200 °C for 5 min.
► The crystallinity resulted by SE–MI process was much lower than that resulted by SE process.