Structural Variation of Bamboo Lignin before and after Ethanol Organosolv Pretreatment

In order to make better use of lignocellulosic biomass for the production of renewable fuels and chemicals, it is necessary to disrupt its recalcitrant structure through pretreatment. Specifically, organosolv pretreatment is a feasible method. The main advantage of this method compared to other lignocellulosic pretreatment technologies is the extraction of high-quality lignin for the production of value-added products. In this study, bamboo was treated in a batch reactor with 70% ethanol at 180 °C for 2 h. Lignin fractions were isolated from the hydrolysate by centrifugation and then precipitated as ethanol organosolv lignin. Two types of milled wood lignins (MWLs) were isolated from the raw bamboo and the organosolv pretreated residue separately. After the pretreatment, a decrease of lignin (preferentially guaiacyl unit), hemicelluloses and less ordered cellulose was detected in the bamboo material. It was confirmed that the bamboo MWL is of HGS type (p-hydroxyphenyl (H), vanillin (G), syringaldehyde (S)) associated with a considerable amount of p-coumarate and ferulic esters of lignin. The ethanol organosolv treatment was shown to remove significant amounts of lignin and hemicelluloses without strongly affecting lignin primary structure and its lignin functional groups.     

Catalytic organosolv fractionation of willow wood and wheat straw as pretreatment for enzymatic cellulose hydrolysis

BACKGROUND: Ethanol‐based organosolv fractionation of lignocellulosic biomass is an effective pretreatment technology for enzymatic cellulose hydrolysis to produce sugars and lignin within a biorefinery. This study focuses on the catalytic effect of H₂SO₄, HCl, and MgCl₂ on organosolv pretreatment of willow wood and wheat straw. RESULTS: The use of catalysts improved fractionation of both feedstocks. The maximum enzymatic cellulose digestibility obtained was 87% for willow wood (using 0.01 mol L^?1 H₂SO₄ as catalyst) and 99% for wheat straw (0.02 mol L^?1 HCl). Non‐catalytic organosolv fractionation at identical conditions resulted in 74% (willow wood) and 44% (wheat straw) glucose yield by enzymatic hydrolysis. Application of catalysts in organosolv pretreatment was particularly effective for wheat straw. The influence of the acid catalysts was found to be primarily due to their effect on the pH of the organosolv liquor. Acid catalysts particularly promoted xylan hydrolysis. MgCl₂ was less effective than the acid catalysts, but it seemed to more selectively improve delignification of willow wood. CONCLUSION: Application of catalysts in organosolv pretreatment of willow wood and wheat straw was found to substantially improve fractionation and enzymatic digestibility. The use of catalysts can contribute to achieving maximum utilization of lignocellulosic biomass in organosolv‐based biorefineries. Copyright © 2011 Society of Chemical Industry     

甘蔗渣的酸催化常压甘油有机溶剂预处理及其酶解

预处理可以打破木质纤维素原料纤维素、半纤维素和木质素三大组分间的顽抗结构,从而提升纤维素基质可酶解性。本文针对目前常压甘油有机溶剂预处理花费时间过长的问题,尝试开展酸催化的常压甘油有机溶剂预处理研究以缩短预处理时间。实验通过单因素选择和响应面Box-Behnken设计优化,获得酸催化常压甘油有机溶剂预处理的最佳条件为：预处理温度245℃,预处理时间38min,硫酸添加质量0.1%。在此条件下获得基质48h酶解率的响应面预测值为94.0%,实际值为91.4%。结果表明响应面优化方案和回归模型适用于本实验,预处理显著提高了基质可酶解性。高浓度基质（15%～20%）酶解进一步证明了预处理后基质具有突出的可酶解性,20%浓度基质在酶载量5FPU/g干基质条件下批次酶解72h,酶解率达60%,葡萄糖浓度达83.4g/L。酸催化常压甘油有机溶剂酸预处理在明显缩短预处理时间的同时,能显著提高木质纤维素基质可酶解性,使后续工业化意义的浓醪酶解糖化成为可能。     

固体超强酸纳米光催化剂SO42--TiO2的制备及Ag改性

以钛酸丁酯为原料,通过在TiO2溶胶中添加质量分数为49%的硫酸,用溶胶–凝胶法制备了固体超强酸纳米光催化剂SO42?-TiO2,并在此基础上用硝酸银进行了改性。用XRD、IR、UV-vis、BET等手段对所制得的试样进行了表征,同时以甲基橙及苯酚的水溶液为模拟污染物,评价了样品的光催化性能,发现SO42--TiO2的光催化活性最高可达单一TiO2的10倍,SO 42?/Ag-TiO2的液相光催化活性超过P-25。     

Thermodynamic modeling of HNO3‐H2SO4‐H2O ternary system with symmetric electrolyte NRTL model

The nitric acid concentration/sulfuric acid concentration (NAC/SAC) process has been widely used for concentrating dilute aqueous nitric acid and recovering spent sulfuric acid. Dilute nitric acid (65 to 80 wt %) is concentrated using sulfuric acid to bind water and break the nitric acid‐water azeotrope at approximately 68 wt % nitric acid. To support heat and mass balance calculations and process simulation for NAC/SAC processes, we develop a comprehensive thermodynamic model for nitric acid‐sulfuric acid‐water ternary system based on previously published thermodynamic models of nitric acid‐water and sulfuric acid‐water binary systems with eNRTL equation. The ternary system model correlates well the isobaric vapor‐liquid equilibrium data at one atmosphere and the water and nitric acid activities data at 273.15 K for the ternary. Contour plots of boiling points, vapor phase composition, and specific heat capacity of the ternary system, as well as a Merkel enthalpy‐concentration chart are generated for engineering use. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3110–3117, 2017     

过氧化氢-乙酸联合预处理对甘蔗渣酶解和发酵的影响

采用过氧化氢-乙酸(HPAC)对甘蔗渣(SCB)进行了联合预处理。以预处理后的甘蔗渣为原料, 先进行酶水解, 然后将水解液进行乙醇发酵, 探讨预处理对甘蔗渣酶解和发酵的影响。实验结果表明: 20 g甘蔗渣, 加入150 mL过氧化氢水溶液(75 mL过氧化氢(30%)和75 mL水)和150 mL乙酸(99%), 硫酸用量为过氧化氢-乙酸溶液体积的0.5%, 在70 ℃反应2 h时, HPAC预处理脱除了88.85%的木质素, 并使90.10%的纤维素保留在底物中。底物(HPAC/70-SCB-0.5)的酶可及度是80.30 mg/g, 与相同条件下单独过氧化氢预处理(HP/70-SCB)和单独乙酸预处理(AC/70-SCB)相比, 分别增加了38.26%和31.08%, 甘蔗渣木质素的表面覆盖率从原料的0.66降低至0.22。酶解上清液在酶用量为5 FPIU/g(以底物计)条件下水解后, 葡萄糖得率是87.63%, 分别是HP/70-SCB和AC/70-SCB的6.89和20.62倍, 发酵产乙醇质量浓度是7.57 g/L, 分别是HP/70-SCB和AC/70-SCB的7.65和22.94倍。     

氧化法制取草酸的工艺探讨

以淀粉作为原料,不预先进行水解,直接投料,在硝酸、硫酸的作用下,催化、氧化制取草酸,所得的产品颜色纯白,纯度大于99%。以淀粉投料计算,草酸得率大于100%。     

Pretreatment of <Emphasis Type="Italic">Helianthus tuberosus</Emphasis> residue by flow-through process for production of fermentable sugar

The pretreatment of Helianthus tuberosus residue was studied for fermentable sugar production. The pretreatment was performed by varying the temperature, type of chemical solution, and concentration. Two different catalytic pretreatments using sulfuric acid and aqueous ammonia were operated and compared in a flow-through column reactor system. The flow-through process was required to increase the sugar production yield of biomass. To selectively remove the lignin of biomass and achieve fractionation of hemicellulose in the liquid phase to produce pentose, the flow-through process could be controlled by the pretreatment conditions. Furthermore, the remaining solid underwent enzymatic hydrolysis for hexose production. The mass balances of biomass pretreated with aqueous ammonia and sulfuric acid solution were compared in terms of production of fermentable sugars. The glucose recovery compared to the initial biomass was 71.2% in the pretreatment using aqueous ammonia at 170 °C, and pretreatment using sulfuric acid solution at 150 °C was 52.3%.     

木薯酒精渣的预处理及补料同步糖化发酵制取乙醇

木薯酒精渣的处置是制约木薯燃料乙醇大规模产业化的问题之一。本文立足于探索木薯酒精渣利用途径,分析了木薯酒精渣的主要成分,对比了氨水、氢氧化钠、氨水组合稀硫酸3种预处理方式对于木薯酒精渣纤维素和木素含量及纤维素酶水解效率的影响,分析了处理前后木薯酒精渣的表面结构及纤维素结晶度,并以氨水处理后的木薯酒精渣为底物,进行了同步糖化发酵。结果表明,3种预处理方法中组合预处理能更好地增加纤维素含量和提高纤维素酶水解效率,与未处理原料相比,组合预处理后纤维素含量增加了111.26%,木素下降了35.05%,酶水解72h纤维素转化率从42.10%增加到61.71%。氨水预处理后,原料的木素含量降低,处理后木薯酒精渣的表面变得更加粗糙,纤维素结晶度有所增加,以氨水处理后的木薯酒精渣为底物进行分批补料同步糖化发酵,当初始底物浓度为100.0g/L,分别在20h、40h、60h进行补料至最终底物浓度为400.0g/L时,发酵120h乙醇浓度达到51.0g/L。     

1,2,3-三氯苯的硝化反应研究

对1,2,3-三氯苯(TCB)经硝化反应合成4,6-二硝基三氯苯进行了研究,考察了其在硝酸/硫酸、硝酸钾/硫酸和有机溶剂中的硝化反应;在混酸体系中,考察了物料配比、反应温度、反应时间对4,6-二硝基三氯苯收率的影响.在65％硝酸/98％硫酸体系中,确定了较优的反应条件为:n(TCB)∶n(硫酸)∶n(硝酸)=1∶11....     

Production of biocatalysts on the basis of recombinant heterologous xylanase producer strains in the Penicillium verruculosum fungus: Their application in the hydrolysis of timber and wood processing industry wastes

The aim of this work was to create biocatalysts with an increased heterologous expression of endo-β-1,4-xylanase of P. canescens using recombinant P. verruculosum strains, to analyze the properties of new enzyme preparations, and to study the saccharifying activity of these preparations in the hydrolysis of plant raw materials, such as hogged aspen and detarred pine wood wastes of the timber and wood processing industries. The xylanase activity of the existing enzymatic preparations is insufficiently high to hydrolyze a xylan-rich biomass. The creation of increasingly xylanolytically active P. verruculosum-based recombinant strains containing homologous or heterologous genes of xylanase and mannanase is therefore a problem of great interest. Using the methods of genetic engineering, we obtained enzymatic preparations that are biocatalysts for the hydrolysis of plant raw material wastes of the sawmilling and wood processing industries and, according to the data of chromatographic fractionation, have compositions of 45–60% cellulase and 20–50% xylanase (which is optimal for the saccharifying of bagasse, along with aspen and pine wood). The originality of our technique lies in the creation of biocatalysts with predetermined properties, thus reducing appreciably the cost of enzyme preparation by eliminating the need to mix components of the carbohydrase complex for the hydrolysis of plant raw materials, e.g., aspen and pine wood.     

Characterization and use of acid‐activated montmorillonite‐illite type of clay for lead(II) removal

The natural local deposits of montmorillonite‐illite type of clay (MIC) were susceptible for acid activation. Raw clay was taken for experimentation, disintegrated on acid activation with sulfuric acid, which showed a particle size distribution. The montmorillonite and illite phases in the raw clay disappeared on acid activation and the activated clay, MIC(AA), showed with sodium‐aluminum‐silicate and beidellite phases apart from quartz (low) phase. The raw and acid‐activated clays were characterized using X‐ray powder diffractometry, X‐ray fluorescence, Fourier transform infrared spectrometry, and energy dispersive X‐ray, and their adsorption capacities were compared. When tested for adsorption of Pb(II) in aqueous solutions, the acid‐activated clay showed about 50% increased adsorption than raw clay. Sips adsorption isotherm and pseudo‐second‐order kinetic models were found to be best for the batch adsorption data. Kinetic studies showed the existence of film diffusion and intraparticle diffusion. A two‐stage batch adsorber was designed for the removal of Pb(II) from aqueous solutions. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

煤灰渣酸浸提铝试验

为实现煤炭资源化分级利用,对东北某热电厂循环流化床锅炉灰渣进行提铝研究。用硫酸在不同的反应条件下酸浸,以获得较高的铝浸出率和合适的酸浸条件,产品为富含硫酸铝的酸浸液和高硅提铝残渣。酸浸实验结果表明,较为合适的酸浸条件为:5mol/L的硫酸、105～110℃的酸浸温度、2h的反应时间和1:3的固液比,此时铝浸出率为91.5%,提铝残渣中SiO₂含量高达87.6%。X射线衍射分析(XRD)和扫描电镜(SEM)分析表明,原始煤灰渣中的铝元素主要以非晶态的化合物形式存在,而非晶态物质具有较高的化学反应活性,促成了较高的铝浸出率。因此,这种循环流化床锅炉的灰渣酸浸提铝提硅较为合适。     

湿法磷酸的工艺研究进展

介绍了以磷矿为生产原料的硝酸法、盐酸法、硫酸法等湿法磷酸生产工艺，并对其工艺进行了说明和比较。突出了湿法磷酸生产中的除氟问题。指出了湿法磷酸产生磷石膏废物将是制约湿法磷酸生产的主要环节。     

一锅法合成O-甲基-N-硝基异脲

采用尿素、硫酸二甲酯、硝酸、硫酸为原料一锅法合成O-甲基-N-硝基异脲。研究了反应温度、时间、催化剂、原料配比对反应收率的影响,确定了优化的工艺条件:原料配比n(尿素)∶n(硫酸二甲酯)=1.3∶1,温度70℃,催化剂50%硫酸,反应时间4 h,总收率为43%,含量在99%以上。     

Effect of the Charge of Solid Particles on the Activation Energy of Acid Decomposition of Phosphorus-Containing Raw Material

Experimental data on the effect of ionogenic surfactants on the charge of fluorapatites and hydroxyapatites in aqueous solutions are analyzed. The effect of cetylpyridinium chloride (a cationic surfactant) and sodium dodecyl sulfate (an anionic surfactant) on the activation energy of decomposition of phosphate raw material by nitric, sulfuric, and phosphoric acids is experimentally studied. It is shown that, regardless of the nature of the solid and liquid reactants, the activation energy is minimal in the isoelectric state of the surface of the solid-phase particles.__________Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 4, 2005, pp. 440–443.Original Russian Text Copyright © 2005 by Dobrydnev, Bogach, Kol’tsova, Beskov.     

On the acidity of liquid and solid acid catalysts. Part 2. A thermodynamic and kinetic study for acid-catalysed nitrations

Solid acids prepared by adding sulfuric acid on silica gel have been used as catalysts in the nitration of nitrobenzenes and their properties have been tested by kinetic studies at 25°C. Nitration rates in concentrated aqueous solutions of sulfuric acid were also analysed and the catalytic efficiencies of sulfuric acid in liquid and solid phase were compared by using kinetic data of analogous compounds. The results show that the solid acid samples exhibit nitrating properties very similar to those observed in concentrated aqueous solutions of sulfuric acid (range of 90 wt%). The relationship between nitration rates and effective concentration of electrophilic species [NO ₂ ⁺ ], determined by studying the protonation–dehydration equilibrium of nitric acid in strong acids (HNO₃ + H⁺ ⇌ H₂O + NO ₂ ⁺ ), was tested to better understand the acidity properties of medium. This revised version was published online in November 2006 with corrections to the Cover Date.     

New aspects in cationization of lignocellulose materials. IV. Modification of aspen wood meal with quarternary ammonium groups

Trimethylammonium-2-hydroxypropyl (TMAHP) derivatives of aspen wood were prepared by the reaction of wood meal with 3-chloro-2-hydroxypropyltrimethylammoniumchloride (CHMAC) in alkaline medium. The TMAHP sample was fractionated and yields and exchange capacities (Q) of individual fractions were compared with beech sawdust fractions obtained under the same conditions. The most evident difference between the two studied wood types was the higher yield (14.5% of starting material) of water-soluble TMAHP–hemicelluloses obtained from aspen wood.     

Effect of Sulphur Dioxide and Sulphuric Acid on Steam Explosion of Aspenwood

Abstract

The use of steam explosion as a pretreatment for woody biomass prior to enzymatic hydrolysis has been proposed in the past. In this study the effect of SO2 impregnation (1.6% SO2 on dry wood input) and H2SO4 impregnation (0.58% H2SO4 on dry wood input) on the exploded substrates produced are compared with the case where no acid was added. Both acid catalysts substantially improve the survival of pentose sugars when treatments of equal severity are compared. H2SO4 however reduces the extent to which lignin may be extracted from the water washed exploded substrates with caustic.

The mode of action of the SO2 has been examined and, at the levels used in this work, approximately 50% of the input sulphur is shown to bind to the substrate forming, most likely, ligno-sulphonates.

The enzymic digestibilities of the acid impregnated steam exploded substrates are compared with those of the non-acid impregnated material and are shown to be more easily saccharified.     

Pretreatment of Rice Hulls for Cellulase Production by Solid Substrate Fermentation

Abstract

Rice hulls via pretreatment served as a solid substrate for cellulase production. Different pretreatment methods, including microwave irradiation, organosolv process catalyzed by acid or alkali were compared. With rice hulls pretreated by microwave irradiation coupled with alkaline pretreatment and rice hulls pretreated with organosolv process catalyzed with acid or alkali, the maxima of filter paper activity (FPA) obtained during the fermentation were 18%, 21%, 31% higher, and maxima of the carboxy‐methyl cellulase (CMCase) were 7.7%, 14%, 16% higher than those obtained with the rice hulls pretreated only with alkali, respectively. The ratios of cellulose degradation were also estimated and they showed similar tendency with the maxima of FPA detected in the fermentation processes.