Pyrolysis-field ionization mass spectrometry of modified bagasse fractions

The fractions obtained from bagasse after activation with 17.5% NaOH, alternative alkylation with quarternary ammonium groups and extraction with 80% ethanol, water and 5% NaOH, were analyzed using pyrolysis-field ionization mass spectrometry (Py-FIMS). The proposed degradation products from lignin were mostly symmetric fragments containing two aromatic rings while the compounds formed from polysaccharides were the result of dehydration reactions. From the temperature-resolved Py-FIMS it could be seen that ethanol-lignin starts to degrade at temperatures lower than 180°C before the degradation of the hemicellulose fraction. The lignin markers are eliminated from hemicellulose fractions before the polysaccharide gasification starts. The quarternary ammonium groups are cleaved from the fractions at temperatures lower than 200°C.     

稻草碱法制浆前酶预处理工艺的研究

以稻草为原料,研究采用木聚糖酶预处理过程中时间、温度、pH值和酶用量等因素对预处理效果的影响。研究得到较适宜的酶预处理工艺条件为：液比1：20,预处理时间120min,预处理温度50℃,预处理pH值为7,预处理酶用量80IU／g。预处理过程未对溶出木素和溶出半纤维素的结构造成实质性的破坏,溶出木素的苯环结构和溶出半纤维素的木聚糖单元的六元环结构都得到了保存。     

Selecting the Pre-Hydrolysis Conditions for Eucalyptus Wood in A Fractional Exploitation Biorefining Scheme

The operating conditions for the autohydrolysis of eucalyptus wood were optimized with a view to maximizing hemicellulose extraction while preserving the integrity of glucan. The influence of the operating conditions used in the soda–anthraquinone pulping of the solid phase resulting from the autohydrolysis process was examined. Autohydrolysis of the raw material at a liquid/solid ratio of 8 kg water/kg material at 180°C for 30 min was found to provide a commercially useful liquid phase containing most of the starting hemicellulose. The autohydrolysis treatment allowed the subsequent production of soda–anthraquinone cellulose pulp and paper with properties as good as or even better than those obtained without the pretreatment.     

Preliminary Studies on Furfural Production from Lignocellulosics

This study focused on the production of furfural from agricultural and industrial biomass residues by a hydrodistillation process. Corncobs, sugarcane bagasse, and eucalypt wood were treated with sulfuric, hydrochloric, and phosphoric acids as catalysts, with different acid concentrations (1.5 to 5.2 mol.L ^?1). In addition, the eucalypt liquor from the auto-hydrolysis, kraft-dissolving pulp production process was also investigated as a source of furfural, using sulfuric and hydrochloric acids as a catalyst (0.9 and 3.9 mol.L ^?1) . Furfural yields of 30.2, 25.8, and 13.9% were achieved for corncob, sugarcane bagasse, and eucalypt wood, respectively, on the basis of biomass dry weight. The efficiency of conversion from pentose to furfural using eucalypt liquor from the auto-hydrolysis kraft process was 71.5% using HCl 3.9 mol.L ^?1 . Due to the presence of a high amount of pentose, corncob produced the highest amount of furfural, followed by sugarcane bagasse and then eucalypt wood.     

超声波辅助碱性H_2O_2法提取酒糟半纤维素组分B

采用超声波辅助碱性H2O2法从酒糟中分离半纤维素B(DGHB),研究碱性提取剂中H2O2体积分数、超声波功率和超声波时间等因素对DGHB得率的影响,并采用L9(33)正交试验对提取条件进行优化。结果表明,超声波辅助碱性H2O2法提取DGHB的最佳条件为:提取剂中的H2O2体积分数2.0%,超声波功率400 W,超声波辐射时间15 min。在该最佳条件下,DGHB得率为28.57%。傅里叶变换红外光谱分析表明,所提取的DGHB具有半纤维素多糖的特征吸收峰。该研究结果可为酒糟半纤维素分离的工业化应用提供参考。     

半纤维素的醚化改性

简单介绍了半纤维素的化学组成及结构特点,对近十年来半纤维素的醚化改性的研究进展进行了综述,主要介绍了半纤维素的羧甲基化、甲基化、季铵化等的醚化反应。展望了半纤维素醚化改性的发展前景。     

Arabinosylated phenolics obtained from SO2‐steam‐pretreated sugarcane bagasse

A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO₂ (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO₂ steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry     

Fractionation of lignocellulosics. Solubilization of corn stalk hemicelluloses by autohydrolysis in aqueous medium

This paper discusses the variation profiles of the three main polymeric families (hemicelluloses, cellulose and lignin) of milled corn stalk (Zea maÿs) after aqueous thermomechanochemical treatment. The experimental system used combine explosion and shear effects facilitating the solubilization of hemicelluloses in the aqueous medium.

Two starting materials (ethanol–benzene extracted and ethanol–benzene and water extracted) was used. Hemicelluloses are totally solubilized at 220°C (10 min) although there is a loss of lignin (up to a third); cellulose is practically unaffected.

A kinetic analysis for the solubilization step was done for calculating the frequency factor and the activation energy for the main treatment using the analytical characterization data from the obtained solid residues.     

半纤维素改性制备膜材料

分析和概述了近年来半纤维素改性制备薄膜材料的最新研究成果。从其潜在的两个应用方面——食品包装材料和可食用包覆膜出发,分别在隔氧性、阻湿性、机械性能等方面对不同改性方法制备的半纤维素薄膜和传统的聚合物薄膜材料作了详细的比较。改性半纤维素膜具有可再生及生物降解性能,其阻隔性能与传统聚合物薄膜材料相当,可望成为一种具有广阔市场前景的新型环保材料。     

Soluble dietary fibres from sugarcane bagasse

Soluble dietary fibres from sugarcane bagasse were extracted under alkaline conditions and characterised. Precipitated fibres were dialysed, and the fibre composition was evaluated before and after the dialysis step. Compositional analysis indicated that the fibres both before and after dialysis consisted of 39% w/w total sugars, 16% w/w protein, 10% w/w Klason lignin and 30% w/w ash. Xylose was the main neutral sugar followed by arabinose with glucose, galactose and uronic acids also present in all samples. The structural properties were also spectroscopically examined, which confirmed the presence of arabinoxylans. Macromolecular characterisation revealed that molecular weight is reduced after dialysis, indicating that a range of dietary fibres with different macromolecular characteristics may be obtained depending on the specific processing steps. The present work shows that soluble arabinoxylans may be obtained from sugarcane agricultural wastes that may be used as a source of novel dietary fibres.