Advanced Materials Research Vols. 236-238

Abstract: Rapid carboxymethylation of xylan-rich hemicelluloses from wheat straw biomass with sodium monochloroacetate and sodium hydroxide in the ethanol/water medium under microwave irradiations was investigated in this paper. The effects of reaction conditions such as the reaction time, the reaction temperature, and the amounts of sodium hydroxide and sodium monochloroacetate on the degree substitution (DS) of carboxymethylated hemicelluloses were discussed. The structures of hemicelluloses before and after the chemical modification were analyzed by ¹³C nuclear magnetic resonance (NMR) spectra. Gel permeation chromatography (GPC) was used to characterize the carboxymethylated hemicelluloses. During the chemical modification, it was found that the remarkable degradation of hemicelluloses occurred under microwave irradiations.

Abstract: A kaolin/sodium lignosulfonate graft acrylic acid and acrylamide superabsorbent composites(KLPAAM) prepared by solution polymerization are used for the equilibrium absorbency test of KLPAAM superabsorbent composite in different metal ion salt solutions. The effects of the solution concentrations on the equilibrium absorbencies in CuCl₂, ZnCl₂, FeCl₃ and AlCl₃ solutions are in order: CuCl₂<ZnCl₂<FeCl₃<AlCl₃. The solution concentrations and the pH values have an important effect on the equilibrium absorbencies. There are different pH values, 3.0 in FeCl₃ and ZnCl₂, 4.25 in AlCl₃ and 6.0 in CuCl₂ solution when the equilibrium absorbencies quickly increase with the pH values of the solutions. And then they reach their relative define values, in which the pH value is 3.8 in FeCl₃, 3.5 in ZnCl₂ and 5.5 in AlCl₃ solution. The absorbency obviously increases again when the pH value is larger than 7.0 in ZnCl₂ solution. They are slightly affected by the solution temperatures, that is, slightly decreases with increasing solution temperatures.

Abstract: In many countries, wheat straw is an abundant byproduct from wheat production in farming, only a minor portion of the straw is reserved as fuel, or raw materials for industry. In order to make good use of wheat straw, a series of materials based them are prepared by acylation grafting with propionic anhydride in a solvent-free system. The capability of the grafted straw to absorb oil from aqueous solution was studied and compared with the raw straw. It is found that wheat straw is more effectively at absorbing oil after chemically modification than the raw one in 15 minutes. And the grafted material is significantly more hydrophobic than the raw wheat straws. Characterization of chemically modified straw was performed by SEM, XRD.

Abstract: To investigate the nutritive and ensiling characteristics of sweet corn processing by-products, the chemical compositions of corn bracts and cobs were analyzed and the effects of wilting and additives on the fermentation quality and aerobic stability were measured. The research results showed: Corn bracts and cobs had low fiber content and high nitrogen free extract content (> 61% DM)，with high nutritive value; Corn bracts and cobs were of high water soluble carbohydrate contents (> 10% DM), low buffering capacity (< 150 mE/kg DM), more lactic acid bacteria (> 10⁷ cfu/g FM), they might be well preserved without any treatments, but their aerobic stability was poor; Barn and lactic acid bacteria addition had few effect on the fermentation except for reducing butyric acid content, wilting tended to increase lactic acid content and reduce the contents of volatile fatty acids.

Abstract: A simple and rapid microwave assisted extraction (MAE) technique for the extraction of flavonoids from the leaves of Syringa oblate was developed. The influence of several extraction variabes on extraction yield of flavonoids were discussed. The optimum extraction conditions obtained were: 50% ethanol solution, 480 W microwave power, 6 min extraction time and 20:1 (mL/g) as the ratio of solvent volume to sample weight. Compared with conventional extraction methods, MAE is an efficient and rapid method for the extraction of the flavonoids from the leaves of Syringa oblate.

Abstract: The object of this research is to investigate the factors influencing the hydrolysis of corn stover by dilute sulfuric acid and the types of sugars existed in hydrolysate. Experiment results showed that the optimal conditions were hydrolysis temperature 120°C, stover size 20-40 mesh, soak time 36h, reaction time 100 min, H₂SO₄ concentration 1.5% and solid-liquid ratio 1:8. Sugars gained in the hydrolysate were xylose 3.0%, glucose 0.71%, mannose 0.12% and galactose 0.32% determined by capillary electrophoresis.

Abstract: A novel benzoxazine-based phenolic resin containing furan groups and long alkyl side-chain (CFB) was synthesized using cardanol-furfural resin as phenolic raw materials. The new benzoxazine-based cardanol-furfural resin derived from renewable resources was characterized by FTIR, ¹H NMR spectra and Differential scanning calorimeter (DSC) etc. The thermal ring-opening reaction of the benzoxazine ring and the polymerization of the double bond were demonstrated with FTIR measurement. The thermal behavior of the cured product was also investigated with thermogravimetric analysis. The corresponding polybenzoxazine showed T_g value higher than that of polybenzoxazine prepared from cardanol, ammonia and formaldehyde. The char yield value at 800°C of the corresponding polybenzoxazine is 46.2% in N₂ atmosphere. The results showed that the polybenzoxazine cured from CFB had good heat resistance and toughness.

Abstract: This paper demonstrated acylation of cellulose with long chain fatty acid and internally plasticized cellulose films obtained by casting. The degrees of substitution (DS) and molar yields of fatty acid, Ts-Cl amounts and reaction time, and as well as the property of final products were studied. Partially derivative celluloses presented glass transition compared to starting cellulose. However, thermal behaviors of the internally plasticized esters with different DS were similar. Dynamic mechanical thermal analysis (DMTA) in tension mode revealed separate relaxations, denoted α and β, corresponding to the glass transition and side-chain melting processes, respectively. According to this, these longer chain esters (LCCEs) showed promise as internally plasticized cellulose films because the supermolecular structure of cellulose was significantly changed with the introduction of longer substituent.

Abstract: The main reason resulting in the greenhouse effect is the fact that CO₂ concentration of atmosphere is raised up. The largest part of CO₂ emissions caused by human activities is derived from coal-fired power plant. Consequently, in order to reduce CO₂ emissions on a large scale, we must focus on capturing CO₂ which is produced by coal-fired power stations. In this paper, we introduce advanced biological CCS technology which makes use of the Chlorella sp. to fix CO₂ from coal-fired power plant. The objective of the work is to discuss the effects of biological conditions (inoculums density, cultivation temperature and light intensity) on carbon sequestration efficiency, and to find a suitable cultivation environment for the growth of Chlorella sp.

Abstract: The aim of this research is to study the saccharification of corncob residues of xylose manufacture by enzymes and turn it to L-lactic acid by fermentation. Corncob residues of xylose manufacture is one kind of lignocelluloses composed of 48.5% cellulose, 21.3% lignin, and 23.5% hemicellulose. As one of the most widely used organic acids in industry and the precursor of PLA, a degradable plastic, L-lactic acid is a very important material. In this study, six kinds of cellulases and one kind of β-glucosidase produced by different companies were studied to obtain high yield sugars needed for L-lactic acid fermentation. Results showed that composite of different enzymes could improve the catalysis effects. Mixture of cellulose F3: cellulose F4: β-glucosidase at the ratio of 2:4:9 engendered a high synergistic effect in hydrolysis. Also, the main factors influencing the hydrolysis of corncob residues were investigated. The appropriate reaction conditions are sodium acetate buffer 0.05-0.1mol/L, pH 5.0-5.5, concentration of corncob residues 15%, enzyme concentration 97U for 1g substrate, reaction temperature 50°C and the shaker speed 140 r/min. After 96h reaction, the concentration of glucose could reach as high as 5.5%. In fermentation, 4.48% of L-lactic acid was produced in 24 hours utilizing hydrolysis sugars as the carbon source, and the percent conversion of glucose to L- lactic acid was 81.5%.