Preparation of a lignocellulose material from wastes

A powder lignocellulose material was prepared from waste paper and characterized. Waste paper is partially hydrolyzed with peroxomonosulfuric acid. Physicochemical characteristics, functional composition, and the IR spectra of the resulting samples were studied. The parameters of supramolecular structure were estimated from the evidence of the IR spectra.     

Thermal analysis of less common lignocellulose fibers

The thermal behavior of four unusual lignocellulose fibers — namely Caroa, Curaua, Piassava and Sponge gourd — is described. Caroa and Curaua fibers showed a more homogeneous thermal degradation, with a single peak dominating in the DTG curve. Piassava and Sponge gourd showed two separated peaks, revealing the more pronounced amounts of hemicellulose present at these fibers. All four fibers are, however, thermally stable up to temperatures of around 200°C. The activation energies for the thermal degradation of the fibers were similar, except for the Caroa fiber. The lower activation energy associated to this fiber was attributed to its higher hemicellulose to cellulose ratio.     

Octyl glucoside inhibits [14C]DHP mineralization whereas peroxidase activity is stimulated inPhanerochaete Chrysosporium

Octyl glucoside stimulated peroxidase formation inPhanerochaete chrysosporium ME-446 cultivated in cellulose-based media. Addition of 0.1% of the nonionic surfactant resulted in a ninefold (143 U/L) and sixfold (119 U/L) increase in LiP formation under conditions of N limitation and N excess, respectively. Octyl glucoside also stimulated MnP formation, but to a lesser extent than observed with LiP. The cellobiose-oxidizing enzymes (cellobiose dehydrogenase and cellobiose:quinone oxidoreductase) were stimulated by octyl glucoside when used at a concentration of up to 0.05%, but higher concentrations gave values similar to those for the controls. Little proteolytic activity was detected in the presence of the surfactant. In general, activities of the enzymes studied were of the same order as those seen using Tween-80. In contrast with Tween-80, octyl glucoside markedly inhibited [¹⁴C]DHP mineralization. Attempts to account for the observed inhibition of synthetic lignin degradation by P.chrysosporium in the presence of octyl glucoside are discussed.     

Preparation and property assessment of neat lignocellulose nanofibrils (LCNF) and their composite films

Lignocellulose nanofibrils (LCNF) were produced from thermo-mechanical pulp (TMP) using a micro-grinder and were characterized with respect to fiber diameter and thermal stability. The initial water content in the TMP affected the defibrillation process and longer grinding time was necessary for the air-dried TMP, resulting in LCNF with higher fibril diameter. As compared to the reference cellulose nanofibrils (CNF) produced through a refining process, LCNF was less thermally stable and started to degrade at a temperature that was 30 °C lower than that of CNF. LCNF obtained from the never-dried TMP was combined with various additives (10 wt%) to produce composite films. The neat LCNF and composite films did not reach the mechanical properties of the neat CNF film that was evaluated as reference. However, the addition of poly(vinyl alcohol) (PVA) at 10 wt% on a dry basis did cause a 46 and 25% increase in tensile strength and elastic modulus, respectively. Other additives including cellulose nanocrystals, bentonite and CNF were also found to increase to some extent the Young’s modulus and ductility of the LCNF composite films whereas the addition of talc did not improve the film performance. Water absorption of neat LCNF films was lower than the reference CNF and was negatively affected by the addition of PVA.     

Molecular organization of DHP membrane fragments

The phase transition of dihexadecyl phosphate (DHP) bilayered disks has been studied using EPR spectroscopy. In the acid form of DHP, a phase transition temperature exists, that we have monitored through the spin-spin interaction between the nitroxide molecules at high concentration (8%) in DHP bilayers. This spin-spin interaction is due to the gathering of solutes in a fluid defect of the membrane: the border. The fluorescence quenching of two probes by the nitroxide stearic acids in DHP bilayers has been studied by stationary and time-resolved fluorescence measurements. The quenching process is mainly static. Both magnetic and fluorescent probes are localized in the periphery of the bilayered disks. An erratum to this article is available at .     

Simultaneous saccharification and fermentation of lignocellulose

Simultaneous saccharification and fermentation (SSF) processes for producing ethanol from lignocellulose are capable of improved hydrolysis rates, yields, and product concentrations compared to separate hydrolysis and fermentation (SHF) systems, because the continuous removal of the sugars by the yeasts reduces the end-product inhibition of the enzyme complex. Recent experiments using Genencor 150L cellulase and mixed yeast cultures have produced yields and concentrations of ethanol from cellulose of 80% and 4.5%, respectively. The mixed culture was employed because B.clausenii has the ability to ferment cellobiose (further reducing end-product inhibition), while the brewing yeastS. cerevisiae provides a robust ability to ferment the monomeric sugars. These experimental results are combined with a process model to evaluate the economics of the process and to investigate the effect of alternative processes, conditions, and organisms.     

Hydrolysis of steam-pretreated lignocellulose

The mechanism of hydrolysis of cellulose is important for improving the enzymatic conversion in bioprocesses based on lignocellulose. Adsorption and hydrolysis experiments were performed with cellobiohydrolase I (CBH I) and endoglucanase II (EG II) from Trichoderma reesei on a realistic lignocellulose substrates: steam-pretreated willow. The enzymes were studied both alone and in equimolar mixtures. Adsorption isotherms were determined at 4 and 40 degrees C during 90-min reaction times. Both CBH I and EG II adsorbed stronger at 40 than at 4 degrees C. The time course of adsorption and hydrolysis, 3 min to 48 h, was studied at 40 degrees C. About 90% of the cellulases were adsorbed within 2 h. The hydrolysis rate was high in the beginning but decreased during the time course. Based on adsorption data, the hydrolysis and synergism were analyzed as function of adsorbed enzyme. CBH I showed a linear correlation between hydrolysis and adsorbed enzyme, whereas for EG II the corresponding curve leveled off at both 4 and 40 degrees C. At low conversion, below 1%, EG II produced as much soluble sugars as CBH I. At higher conversion, CBH I was more efficient than EG II. The synergism as function of adsorbed enzyme increased with bound enzyme before reaching a stable value of about 2. The effect of varying the ratio of CBH I:EG II was studied at fixed total enzyme loading and by changing the ratio between the enzymes. Only a small addition (5%) of EG II to a CBH I solution was shown to be sufficient for nearly maximal synergism. The ratio between EG II and CBH I was not critical. The ratio 40% EG II:60% CBH I showed similar conversion to 5% EG II:95% CBH I. Modifications of the conventional endo-exo synergism model are proposed.     

Ethanolic fermentation of lignocellulose hydrolysates

Applied Biochemistry and Biotechnology -     

Preparation and Crystal Structure of PrNb_5O_(14)

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Preparation and properties of 14-cyano-Δ10-dodecahydroacridine

14-Cyano-¹⁰-dodecahydroacridine, the product of the partial dehydrocyanation of 11,14-dicyanoperhydroacridine, has been obtained. The behavior of this substance to acids and alkalies and also its hydrocyanation, autooxidation, disproportionation, and hydrogenation reactions have been studied. On the basis of IR spectral data, the hypothesis has been put forward that this substance exhibits imine-enamine tautomerism.     

Ethanolic fermentation of pentoses in lignocellulose hydrolysates

Applied Biochemistry and Biotechnology - In the fermentation of lignocellulose hydrolysates to ethanol, two major problems are encountered: the fermentation of the pentose sugar xylose, and the...     

Detoxification of biological fluids by lignocellulose ion-exchangers

Detoxification capabilities of N- and S-containing phytosorbents based on grafted copolymers of wood and lignin for blood serum of patients with various ophthalmic pathologies, including diabetic retinopathy, were determined. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 400–404, July–August, 2008     

Preparation,crystal structure,and properties of HgSnP14 and other polyphosphides with HgPbP14-type structure

The new compound HgSnP₁₄ and the known isotypic polyphosphides HgPbP₁₄ and MM′P₁₄ (M = Zn, Cd; M′ = Sn, Pb) were prepared by reaction of the elemental components in evacuated silica tubes. They are diamagnetic semiconductors with bandgaps ranging from 0.4 ± 0.2 eV for HgPbP₁₄ to 1.6 ± 0.1 eV for ZnSnP₁₄. The crystal structure of CdSnP₁₄ was refined from single-crystal X-ray counter data to a residual of R = 0.040 for 83 variable parameters and 1182 structure factors. The crystal structure and physical properties of these polyphosphides are briefly discussed.     

木质纤维素类生物质组分分离研究进展

木质纤维素类材料在地球上大量存在,来源广泛. 对木质纤维素废料进行处理,可以废物回收,避免环境问题. 由于木质纤维素材料细胞壁较厚,细胞壁中含结晶结构,进行透射电子显微镜观察前需经过前处理. 对木质纤维素材料的样品前处理方法进行了详细说明,包括取材、固定、洗涤、脱水、包埋和渗透、切片及染色,可为其制备提供参考.     

Preparation and characterization of 16-benzoylated tetraaza[14]annulenes

The condensation reaction between tetraaza[14]annulene ( 1 ) and a series of para-substituted benzoyl chlorides led to the 16-benzoylated corresponding products in 13–21% yields, but 1 was unreactive with alkyl acid chlorides and easily cleaved in macrocyclic framework. The mass spectra show the presence of molecular ion peaks which support the 16-benzoylated products. A strong ir band due to the C = N stretching mode of the macrocyclic moiety was observed at 1610 cm^?1 and shifted slightly toward higher energy upon benzoylation. An intense ir band which was associated with a C = 0 stretching mode was newly observed at 1640 cm¹. The very strong absorption band about 29000 cm^?1 was attributed to the π ? π* transition and gave a slight shift to higher frequency on benzoylation. All proton signals except for methyl protons exhibit downfield shifts due to the deshielding effect of the substituted benzene ring, but the methyl proton peaks show upfield shifts due to the shielding effect caused by the magnetic anisotropy of the substituted benzene ring. The ¹³C nmr result is also in accord with that of ¹H nmr.     

Detoxification of lignocellulose hydrolysates with ion-exchange resins

Lignocellulose hydrolysates contain fermentation inhibitors causing decreased ethanol production. The inhibitors include phenolic compounds, furan aldehydes, and aliphatic acids. One of the most efficient methods for removing inhibiting compounds prior to fermentation is treatment of the hydrolysate with ion-exchange resins. The performance and detoxification mechanism of three different resins were examined: an anion exchanger, a cation exchanger, and a resin without charged groups (XAD8). A dilute acid hydrolysate of spruce was treated with the resins at pH 5.5 and 10.0 prior to ethanolic fermentation with Saccharomyces cerevisiae. In addition to the experiments with hydrolysate, the effect of the resins on selected model compounds, three phenolics (vanillin, guaiacol, and coniferyl aldehyde) and two furan aldehydes (furfural and hydroxymethyl furfural), was determined. The cation exchanger increased ethanol production, but to a lesser extent than XAD-8, which in turn was less effective than the an ion exchanger. Treatment at pH 10.0 was more effective than at pH 5.5. At pH 10.0, the anion exchanger efficiently removed both anionic and uncharged inhibitors, the latter by hydrophobic interactions. The importance of hydrophobic interactions was further indicated by a substantial decrease in the concentration of model compounds, such as guaiacol and furfural, after treatment with XAD-8.     

Mechanical deconstruction of lignocellulose cell walls and their enzymatic saccharification

Laboratory mechanical softwood pulps (MSP) and commercial bleached softwood kraft pulps (BSKP) were mechanically fibrillated by stone grinding with a SuperMassColloider^®. The extent of fibrillation was evaluated by SEM imaging, water retention value (WRV) and cellulase adsorption. Both lignin content and mechanical treatment significantly affected deconstruction and enzymatic saccharification of fibrillated MSP and BSKP. Fibrillation of MSP and BSKP cell walls occurs rapidly and then levels off; further fibrillation has only limited effect on cell wall breakdown as measured by water retention value and cellulase adsorption. Complete (100 %) saccharification can be achieved at cellulase loading of 5 FPU/g glucan for BSKP after only 15 min fibrillation with energy input of 0.69 MJ/kg. However, the presence of lignin in MSP affects the extent of fibrillation producing fibrils mainly above 1 μm. Lignin binds nonproductively to cellulases and blocks cellulose thereby reducing its accessibility. As a result, the cellulose saccharification efficiency of MSP fibrils (6 h of fibrillation, energy input of 13.33 MJ/kg) was only 55 % at same cellulase loading of 5 FPU/g glucan.