Pretreatment of corn stover via sodium hydroxide-urea solutions to improve the glucose yield

Because of the abundance and renewability of lignocellulosic biomass, lignocellulose-derived biofuels and chemicals are promising alternatives to fossil resources. In this study, we developed a strategy for pretreating lignocellulose (corn stover) using a sodium hydroxide-urea solution (SUs) and evaluated changes in the efficiency and structure. The results showed that treatment with 6% NaOH/12% urea at 80 °C for 20 min gave a glucose yield of 0.54 g/g corn stover. Recycling of the NaOH/urea was also explored, and the average glucose yield over four pretreatment cycles was 0.44 g/g corn stover. The structural characteristics of corn stover were investigated by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. Compared with untreated corn stover, NaOH/urea-pretreated corn stover had more micropores, mesopores, and macropores, higher crystallinity, and a higher cellulose content. This pretreatment process is economical and efficient and has good application prospects for lignocellulose biorefinery.