Ensiling Agricultural Residues for Bioethanol Production

The potential of using ensiling, with and without supplemental enzymes, as a cost-effective pretreatment for bioethanol production from agricultural residues was investigated. Ensiling did not significantly affect the lignin content of barley straw, cotton stalk, and triticale hay ensiled without enzyme, but slightly increased the lignin content in triticale straw, wheat straw, and triticale hay ensiled with enzyme. The holocellulose (cellulose plus hemicellulose) losses in the feedstocks, as a result of ensiling, ranged from 1.31 to 9.93%. The percent holocellulose loss in hays during ensiling was lower than in straws and stalks. Ensiling of barley, triticale, wheat straws, and cotton stalk significantly increased the conversion of holocellulose to sugars during subsequent hydrolysis with two enzyme combinations. Enzymatic hydrolysis of ensiled and untreated feedstocks by Celluclast 1.5 L-Novozyme 188 enzyme combination resulted in equal or higher saccharification than with Spezyme CP-xylanase combination. Enzyme loadings of 40 and 60 FPU/g reducing sugars gave similar sugar yields. The percent saccharification with Celluclast 1.5 L-Novozyme 188 at 40 FPU/g reducing sugars was 17.1 to 43.6%, 22.4 to 46.9%, and 23.2 to 32.2% for untreated feedstocks, feedstocks ensiled with, and without enzymes, respectively. Fermentation of the hydrolysates from ensiled feedstocks resulted in ethanol yields ranging from 0.21 to 0.28 g/g reducing sugars.     

Potential of Agricultural Residues and Hay for Bioethanol Production

Production of bioethanol from agricultural residues and hays (wheat, barley, and triticale straws, and barley, triticale, pearl millet, and sweet sorghum hays) through a series of chemical pretreatment, enzymatic hydrolysis, and fermentation processes was investigated in this study. Composition analysis suggested that the agricultural straws and hays studied contained approximately 28.62-38.58% glucan, 11.19-20.78% xylan, and 22.01-27.57% lignin, making them good candidates for bioethanol production. Chemical pretreatment with sulfuric acid or sodium hydroxide at concentrations of 0.5, 1.0, and 2.0% indicated that concentration and treatment agent play a significant role during pretreatment. After 2.0% sulfuric acid pretreatment at 121 degrees C/15 psi for 60 min, 78.10-81.27% of the xylan in untreated feedstocks was solubilized, while 75.09-84.52% of the lignin was reduced after 2.0% sodium hydroxide pretreatment under similar conditions. Enzymatic hydrolysis of chemically pretreated (2.0% NaOH or H2SO4) solids with Celluclast 1.5 L-Novozym 188 (cellobiase) enzyme combination resulted in equal or higher glucan and xylan conversion than with Spezyme(R) CP- xylanase combination. The glucan and xylan conversions during hydrolysis with Celluclast 1.5 L-cellobiase at 40 FPU/g glucan were 78.09 to 100.36% and 74.03 to 84.89%, respectively. Increasing the enzyme loading from 40 to 60 FPU/g glucan did not significantly increase sugar yield. The ethanol yield after fermentation of the hydrolyzate from different feedstocks with Saccharomyces cerevisiae ranged from 0.27 to 0.34 g/g glucose or 52.00-65.82% of the theoretical maximum ethanol yield.     

球型木质素碳化树脂的制备及性能研究

利用酸法制桨的木质素磺酸盐废液合成的球形木质素阳离子交换树脂,直接制备木质素碳化树脂;考察了碳化条件,运用电子显微镜,热重分析,Ｘ射线衍射等仪器对木质素碳化树脂的结构,碳化失重,孔结构,比表面和吸附量等性能进行了研究。     

纸浆卡伯值的可见分光光度法在线测量

卡伯 (Kappa)值是纸浆质量的重要指标 ,而纸浆中的木素含量决定了纸浆的卡伯值。该文研究了用可见分光光度法在线测量酸法制浆过程蒸煮液中溶出的木素含量去预测纸浆中木素含量和纸浆卡伯值的方法 ;确定了合适的可见光光谱测量波段 (460～580nm) ;建立了纸浆卡伯值与蒸煮液吸光度 (A)的相关方程。结果显示卡伯值与A之间有良好的线性关系 ,为实现蒸煮过程纸浆卡伯值的在线测量提供了依据。     

Oxidative cracking of precipitated hardwood lignin by hydrogen peroxide

Precipitated hardwood lignin (PHL) is a major byproduct in the biomassto-ethanol process. Oxidativecracking of PHL by hydrogen peroxide in aqueous medium was investigated as a means to produce potentially useful chemicals. The cracking reaction takes place at moderate temperatures (80–160°C), giving mono-and dicarboxylic acids as the main products. The yields of these products are in the range of 30–50% of initial lignin. The reaction mechanism and the product distribution are dependent upon the reaction conditions, especially the pH. The reaction under strong alkaline condition proceeds well even at low reaction temperatures (80–90°C). Under acidic conditions, higher temperatures (130–160°C) are required to attain the same degrees of cracking. The reaction patterns of the oxidative cracking reaction involve the cleavage of lignin ring, aryl ether bond, or other linkages within lignin. By using the findings of this investigation and those of previous work, we have illustrated the reaction pathways for degradation of PHL under alkaline and acidic conditions. Aldehydes and aromatic acids are interm ediate products in the oxidative degradation of lignin. However, they were produced only in trace amounts owing to rapid degradation induced by hydrogen peroxide. Presented at the 21st Symposium on Biotechnology for Fuels and Chemicals, Fort Collins, CO, May 1999.     

Application of Waste Liquids Containing Lignin from Pulp-producing Industry to CWM Preparation

IntroductionSince the first oil crisis in1 973,coal conver-sion technologies such as coal gasification,lique-faction and combustion have been studied in orderto use coal as an alternative resource of oil.In thiscontext,coal water mixtures( CWMs) are attrac-tive because they are more transportable andstorable than non- treated coal for being used as analternative resource of oil.To prepare CWMs witha higher energy density,the coal concentrationshould be high in CWMs.However,high coal con-ce…     

Ultrasound-enhanced extraction of lignin from bamboo (Neosinocalamus affinis): characterization of the ethanol-soluble fractions

Bamboo was submitted to ultrasound-assisted extraction in aqueous ethanol to evaluate the effect of ultrasonic irradiation on the dissolution of lignin. In this case, the dewaxed bamboo culms were subjected to ball milling for 48 h, and then were suspended in 95% ethanol followed by ultrasonic irradiations for varied times at 20 °C to obtain ethanol-soluble fractions. The structural and thermal properties of the ethanol-soluble fractions were comparatively investigated by chemical analysis including alkaline nitrobenzene oxidation, bound carbohydrate determination, FT-IR spectra, HSQC spectra, TG, and DTA. The results showed that the yields of the ethanol-soluble fractions were between 4.29% and 4.76% for the fractions prepared with ultrasonic irradiation time ranging from 5 to 55 min, as compared to 4.02% for the fraction prepared without ultrasonic irradiation. It was found that the lignin content of the fraction increased with the increase of the ultrasonic irradiation time. There was a slight increase of the molecular weight of the lignin with the increase of the ultrasonic irradiation time. Alkaline nitrobenzene oxidation coupled with HSQC analysis indicated that the lignin in the fractions was mainly composed of G S H type units as well as minor amounts of ferulic acids. In addition, the fraction prepared with ultrasonic irradiation exhibited a slightly higher thermal stability as compared to the fraction prepared without ultrasonic irradiation.     

INFRARED AND RAMAN SPECTROSCOPY IN PAPER AND PULP ANALYSIS

Infrared and Raman spectroscopy are essential analytical tools for the structural analysis of paper and pulp chemistry. The studies of cellulose, hemicellulose, lignin, thermal- and photo-induced oxidation; cross-linking; and various chemical treatments of pulp and paper products are all made possible using these forms of molecular spectroscopy. In this review, containing 70 references, a broad range of applications into pulp and paper materials, components, and processes is described from recent and classic research over predominantly the past 20 years.     

Abrasive Stripping Voltammetric Studies of Lignin and Lignin Model Compounds

Lignin is potentially a major renewable, nonfossil source of aromatic and cyclohexyl compounds. In this study, we have investigated the abrasive stripping voltammetry of lignin and four lignin model compounds in the room temperature ionic liquids (RTILs) [C₄mim][NTf₂], [N_6,2,2,2][NTf₂] and [C₄mim][OTf] (where [C₄mim]⁺=1‐butyl‐3‐methylimidazolium, [N_6,2,2,2]⁺=n‐hexyltriethylammonium, [NTf₂]^?=bis(trifluoromethanesulfonyl)imide and [OTf]^? =trifluoromethanesulfonate) on a gold macrodisk and in 0.1 M H₂SO₄ and 0.1 M NaOH on a boron‐doped diamond (BDD) macroelectrode, with the hope of using the voltammetry to fingerprint the functional groups within the lignin molecule. The use of RTILs on metal electrodes, or either acidic or basic media in combination with BDD electrodes allows solvent systems with wide electrochemical potential windows, useful for studying voltammetry which may be difficult to observe in systems where early breakdown of the solvent occurs.     

Lignin and starch as potential inductors for biodegradation of films based on poly(vinyl alcohol) and protein hydrolysate

The objective of this work was to study the biodegradation of blow-moulded films of poly(vinyl alcohol) (PVA)/protein hydrolysate (PH) which contain biodegradation inductors of the starch (S) and lignin (LI) types. These increase the biodegradation rate of PVA while preserving or improving the technical and usage properties of blends. The aim of the work was to reach the maximum breakdown rate so that rapid disintegration of PVA could take place at a wastewater treatment plant. The biological material chosen was activated sludge from a municipal wastewater treatment plant. Preparation of the blends required that a plasticiser be used, in this case glycerol (G). This allowed for successful processing but prolonged the lag phase of PVA breakdown as well as reducing its final biodegradation percentage. The influence of G, in this respect, was not affected by incorporating PH. S and LI reduced the influence of the plasticiser but caused a breakdown rate comparable to PVA itself. Contrarily, after adapting biomass to PVA, applying G produced a PVA breakdown rate three times greater, albeit with a lag phase prolonged fivefold. However, due to the duration of breakdown (the period above the retention time of wastewater during activation), this effect was not positive. The addition of PH to the blends mentioned did not exhibit any clear favourable influence. Adding S  resulted in a shorter lag phase, in addition to which the degradation rate increased by approximately 1.5 times. Combining LI and S distinctly accelerated the degradation of a blend, although a disadvantage of doing so is an incomplete breakdown of the substrate, which lowers the final biodegradation percentage. Therefore, an eventual compromise was arrived at, this being a blend of PVA/G PH S. Its breakdown time is half that of pure PVA, and the films produced, from a mechanical standpoint, are more convenient.