Chunsheng Pang

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.

Preparation and antimicrobial property of chitosan oligosaccharide derivative/rectorite nanocomposite

Microwave irradiation was used to intercalate quaternized carboxymethyl chitosan oligosaccharide (QCMCO) into the layer of rectorite (REC) to prepare QCMCO/REC (QCOR) nanocomposites in 70 min, which was much faster than conventional heating method of 48 h. The structures and morphology of QCOR nanocomposites were characterized by XRD, TEM, FT-IR and zeta potential analysis, the thermal behavior and antimicrobial activity of QCOR nanocomposites were also discussed. The results revealed that the interlayer distance of QCOR nanocomposites enlarged with the increase of QCMCO content, hydrogen bonding and electrostatic interaction between QCMCO and REC took place. As compared to QCMCO, the crystallinity of QCOR nanocomposites reduced, the thermal stability of QCOR nanocomposites improved, and the inhibitory activity of QCOR nanocomposites against microorganisms was stronger, the lowest minimum inhibition concentration was only 0.025% (w/v), the antimicrobial mechanism was discussed via TEM and SEM micrographs.

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.

Detoxification of Wheat Straw Hydrolysis in Formic Acid Reaction System by D311 Ion-exchange Resin

Formic acid hydrolysis is widely used in lignocellulose pretreatment. However, formic acid hydrolysis wheat straw cannot be directly used as a fermentation substrate owing to various fermentation inhibitors, especially the formic acid in reaction system and released during pretreatment. Study found treatment of wheat straw hydrolysate with D311 ion-exchange resin had a good result on reduction formic acid. We investigated the influence of D311 resin content on the elimination of residual formic acid and the adsorbance of glucose. The results reveal that 22.5 g D311 resin can eliminate 94% of residual formic acid and with only 15% reducion of glucose concentration.

Catalytic Conversion of Glucose to 5-hydroxymethylfurfural over Aluminum Acetylacetonate in the Two-phase Water-Methylisobutylketone System

5-hydroxymethylfurfural (5-HMF) is a kind of new green platform chemical with wide application. Glucose, which is the unit compound of cellulose, is one of the most important starting chemicals from biomass. With its low cost and wide supply, the conversion of glucose to HMF has attracted the interests of researchers. In this work, a systematic study has been conducted to evaluate the effects of operating conditions on glucose conversion to to 5-HMF using Al(acac)3 catalyst in water-4-Methyl-2-pentanone two-phase system. The results showd that the conversion rate and the selectivity of glucose to 5-HMF with Al(acac)3 as catalyst were higher than those with AlCl3, CrCl3, Zr3(PO4)4, MCM-41 molecular sieves and 732 Cation Exchange Resin, so Al(acac)3 catalyst was selected for further studies. The optimum preparation conditions of 5- HMF catalyzed by Al(acac)3 were as follows: temperature at 180 ¿, dosage of catalyst at mol% (based on the mass fraction of glucose), two phase ratio of 8:2 (water/methylisobutylketone), reaction time of 1.5 h. The conversion rate of glucose was found to be 98.91%, the 5-HMF yield and product selectivity was 45.91% and 46.14% respectively.