Qiulin Yang

Changes of the surface structure of corn stalk in the cooking process with active oxygen and MgO-based solid alkali as a pretreatment of its biomass conversion

This study presents a novel, efficient and environmentally friendly process for the cooking of corn stalk that uses active oxygen (O2 and H2O2) and a recoverable solid alkali (MgO). The structural changes on the surface of corn stalk before and after cooking were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. The results showed that lignin and extractives were effectively removed, especially those on the surface of corn stalk. Additionally, the changes included becoming fibrillar, the exposure of cellulose and hemi-cellulose and the pitting corrosion on the surface, etc. The results also showed that the removal reaction is from outside to inside, but the main reaction is possibly on the surface. Furthermore, the results of active oxygen cooking with a solid alkali are compared with those of alkaline cooking in the paper.

The structural changes of the bagasse hemicelluloses during the cooking process involving active oxygen and solid alkali.

This work describes the structural changes of bagasse hemicelluloses during the cooking process involving active oxygen (O(2) and H(2)O(2)) and solid alkali (MgO). The hemicelluloses obtained from the bagasse raw material, pulp, and yellow liquor were analyzed by high-performance anion-exchange chromatography (HPAEC), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), and (1)H-(13)C 2D hetero-nuclear single quantum coherence spectroscopy (HSQC). The results revealed that the structure of the bagasse hemicelluloses was L-arabino-(4-O-methylglucurono)-D-xylan. Some sugar units in hemicelluloses were oxidized under the cooking conditions. Additionally, the backbones and the ester linkages of hemicelluloses were heavily cleaved during the cooking process.

Efficient enzymatic hydrolysis of the bagasse pulp prepared with active oxygen and MgO-based solid alkali

The enzymatic hydrolysis of the bagasse pulp prepared from the treatment process with active oxygen and MgO-based solid alkali was studied. The hydrolysates were tested by IC (ionic chromatography) for the analysis of monosaccharide. Additionally, the changes of pulp before and after hydrolysis were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), Kajaani cellulose automatic analyzer and atomic force microscopy (AFM) techniques. The results showed that an optimized sugar yield of 82.38% was obtained at the substrate concentration of 5% for 72h with the enzyme dosage of 15IU/g. Furthermore, as the length of the cellulose fiber decreased, the crystallinity of cellulose increased, and more depressions appeared on the surface of pulp after enzymatic hydrolysis.