不同提取方法对所得稻壳基木质素的影响研究

本文以稻壳这种在我国来源十分丰富的农业副产物为原料,采用三种方法(乙二醇法、乙醇法、碱法)提取稻壳中的木质素,考察相应处理条件下的木质素提取率、羟基含量来确定提取适宜条件。乙二醇提取法所得木质素的羟基值和产率可以分别达到275.2mg/g和45.2%;乙醇法在适宜的提取条件下得到稻壳基木质素羟基值和产率分别为269.1mg/g和51.1%;碱溶液提取法可获得羟基值和产率分别为324.7mg/g和64.1%的碱木质素,无论何种木质素都富含活性官能团为后续再利用提供条件。     

二维红外光谱法分析纤维素

采用二维红外光谱法分析纤维素。在293~393K范围内,分别测定脱脂棉纤维的一维红外光谱、二阶导数红外光谱和去卷积红外光谱。结果表明:脱脂棉纤维中的α-纤维素在559cm-1有一个的红外特征吸收峰,β-纤维素在893,1 206,1 235cm-1处有红外特征吸收峰;随测定温度的升高,559cm-1处红外吸收强度降低,893,1 206,1 235cm-1处红外吸收强度增加。进一步采用二维红外光谱研究温度对于脱脂棉纤维结构的影响,结果表明:随测定温度的升高,脱脂棉纤维红外特征吸收峰强度增加的顺序为893cm-11 235cm-11 206cm-1559cm-1。     

3,4,5-三甲氧基苯甲酸酯化壳聚糖的紫外吸收性能研究

将壳聚糖在甲磺酸中充分溶胀后,与3,4,5-三甲氧基苯甲酰氯反应,得到壳聚糖改性高分子紫外 线吸收剂。FTIR的表征表明:与壳聚糖相比,改性产物的红外谱图中1 720 cm-1处归属于C=O伸缩振动和 1 160 cm-1处归属于C-O-C对称伸缩振动的吸收峰显著增强,表明了酯化反应的发生。紫外光谱表明:产 物在220nm和274nm处具有较强的吸收峰。通过元素分析计算出不同投料比下所得改性产物的取代度,并 结合紫外光谱测试所得的数据,计算出了改性产物在273 nm处的摩尔消光系数e为8 205.9 L／(mol·cm)。     

荷移光度法测定双嘧达莫

用光度法研究了双嘧达莫与氯冉酸之间发生的电荷转移反应,其中双嘧达莫是电子给予体,氯冉酸是电子接受体,反应介质是乙醇丙酮混合溶剂。应用等摩尔连续变换法和摩尔比法测得荷移络合物的组成为1∶1,稳定常数为3.9×104。络合物在526nm波长处有最大吸收,双嘧达莫浓度在10～380mg·L-1范围内服从比耳定律,相关系数为0.9996,表观摩尔吸光系数为1.34×103L·mol-1·cm-1,回收率为98.4%,测定结果的相对标准偏差为1.14%。应用该法可以快速测定双嘧达莫片中有效成分的含量,结果满意。     

傅里叶变换红外光谱诊断地中海贫血症

为建立简单快速的地中海贫血诊断方法,本研究探讨了以傅里叶变换红外光谱结合水平衰减全反射(FTIR-HATR)技术在地中海贫血诊断中的制样方法及光谱的数据处理方法.在制样预处理中,通过对样品进行稀释并干燥成膜消除水分子对光谱吸收干扰,保持ATR光谱中各波长对样品的穿透深度一致.结果表明,当1652 cm-1吸收度小于1.5时(即透射率T小于4%时),各波峰强度与血红蛋白浓度呈良好的线性关系(r>0.995)及实验重复性(RSD<4%).在数据处理上,改进的相对强度方法用于800～1780 cm-1和2480～3600 cm-1区间的分析.通过与常规的傅里叶去卷积谱及差谱方法相比,本方法可消除样品浓度所带来的影响因素,灵敏地揭示群体数据中组分与结构在不同组间的显著差异,如1638 cm-1处重叠的蛋白二级结构峰,1172 cm-1、1440 cm-1表征脂类物质的吸收峰,1064 cm-1表征磷酸化合物峰位及表征SH的2553 cm-1附近的吸收峰在正常组与地中海贫血组间存在显著差异.从而避免了几个峰位的相对强度所反映的信息不足及选择参比峰的困扰,对揭示整体的差异变化规律有着重要的作用.     

溶剂在丁腈基聚氨酯中的溶解和扩散

用石英弹簧法和示差扫描量热法 (DSC)、红外分光光度计 (FTIR)研究了苯、乙醇、丙酮、醋酸乙酯和1,2 二氯乙烷五种溶剂在端羟基聚丁二烯 丙烯腈共聚物为软段的聚氨酯中的溶解和扩散行为 .结果表明所有溶剂在丁腈聚氨酯中的扩散均为非费克扩散 ,且随着溶剂蒸汽压增大偏离费克扩散的程度增大 .相同相对蒸汽压下 1,2 二氯乙烷和醋酸乙酯偏离费克 (Fickian)扩散的程度较大 ,而乙醇、丙酮和苯则较小 ,这主要与它们和丁腈软段溶解度参数的极性分量和氢键分量有关 .1,2 二氯乙烷和苯在HTBN PU中的溶解度较高 ,而乙醇 ,醋酸乙酯和丙酮较低 ,主要与它们和丁腈软段溶解度参数的色散分量有关 .所有溶剂均表现出近似Flory Huggins型等温吸收曲线 .红外表明吸收溶剂后 ,氨基甲酸酯基团的氢键化程度有不同程度的下降 ,和溶剂与之形成氢键的能力大小有关 .力学性能表明非极性溶剂苯对材料的力学性能影响较小 ,而乙醇 ,醋酸乙酯和丙酮由于可与氨酯基团形成氢键 ,对原HTBN PU中氨酯键氢键的破坏大 ,力学性能下降大     

ZnCl2催化木质素磺酸盐加氢液化的溶剂效应

选用ZnCl₂为催化剂在高压反应釜中进行加氢液化反应,利用GC-MS和红外光谱技术,研究溶剂极性及供氢能力对木质素磺酸盐液化产率及产物的影响。产率分析表明,极性溶剂有利于木质素液化转化,供氢溶剂有利于提高轻馏分产率,水溶剂条件下木质素液化转化率最高,甲醇溶剂体系条件下轻馏分产率最高,相对最低液化转化率及轻馏分产率的1,4二氧六环溶剂体系分别提高2.0倍和1.9倍。GC-MS分析表明,中等极性溶剂有利于中间产物溶解稳定,供氢溶剂四氢萘通过释放氢自由基结合稳定中间产物。乙醇溶剂条件下中间产物相对含量是48.76%,相对最低含量水溶剂体系提高2.2倍。红外光谱分析表明,醇类溶剂参与反应,焦油产物羟基峰强度增强。     

多胺型螯合纤维的结构表征和性能

以聚丙烯腈纤维为原料,采用化学改性法,制备了多胺型螯合纤维.运用红外光谱分析,表征其化学结构、活性功能基,由IR图谱可知,—CN的特征峰几乎完全消失、1644 cm-1处的—N—C N特征峰的出现,以及1600 cm-1附近的—NH2弯曲振动峰、1580 cm-1附近的—NH弯曲振动峰证实了N,N配位的功能基团——脒基及胺基的存在;采用示差扫描量热仪(DSC)分析改性前后纤维的热稳定性及其变化原因,因改性后纤维的结构改变较大,其热稳定性也相对降低;以扫描电镜仪(SEM)测试分析纤维制备过程中的微观形貌变化与其性能之间的关系;通过机械强度及直径测量,研究了改性前后纤维的机械性能变化,并对影响制备较高强度功能纤维的因素进行了分析;结合滴定曲线、交换容量,测定该纤维的化学稳定性及吸附性能.结果表明,该功能纤维表面及截面内均有较多的沟槽和微孔结构,具有较好的机械性能和化学稳定性,该纤维使用的最佳pH值范围是2.0~8.0,交换容量平均值为10 mmol.g-1.     

矿物药金礞石的红外光谱分析

采用傅立叶红外光谱法分析了金礞石试样,对所得图谱进行解析,发现试样的红外光谱具备层状硅酸盐矿物的吸收特征.其吸收带主要分为4个区域:3 700～3 000 cm-1区间的OH伸缩振动吸收,1 620 cm-1左右处的H2O弯曲振动吸收,1 000 cm-1左右处的Si-O伸缩振动吸收和550～400 cm-1区间的Si...     

碱解聚对玉米秸秆的影响

以玉米秸秆为研究对象,氢氧化钠为解聚剂,研究了碱解聚前后玉米秸秆组份、表面形态、化学官能团和纤维结晶度的变化。结果表明:玉米秸秆中木质素的主要组成单体是H-木质素,解聚液中的酚类物质有4-羟基苯甲醛、香草醛、紫丁香醛、对香豆酸和阿魏酸。玉米秸秆经碱解聚,表面形态变得疏松而多孔,红外光谱下木质素的特征吸收峰消失,85%的木质素和52%的半纤维素被脱除,而纤维素的相对含量增加,结晶度增大。说明碱解聚有利于后续酶解和(或)其它生化方法的实施,以实现秸秆纤维的高值转化。     

Application of sequential aqueous steam treatments to the fractionation of softwood

The FIRST (Feedstock Impregnation and Rapid Steam Treatment) approach was used in this study to isolate extractives, hemicellulose, lignin, fibers, and cellulosic fines of softwood. With hydrolysis and fermentation of the hemicellulose and cellulosic fines fractions, this approach produces four co-products: extractives, cellulose, lignin, and ethanol. The first unit operation uses aqueous/alcohol to remove and recover the extractive rich fraction. The second unit operation uses steam treatment to destructure the matrix and solubilize a large fraction of the hemicelluloses. The third unit operation uses alkaline delignification to dissolve a lignin fraction. The fourth unit operation uses the refining process to separate fibers from cellulosic fines. The fibers are bleached. The yields of lignin and bleached cellulose were about 20.0 kg and 38.3 kg out of 100 kg initial dry pine, respectively. The recovered hemicelluloses were 23.3 kg (containing 16.1 kg hexoses and 5.0 kg pentoses) and the cellulose fines derived hexoses amounted to 3.4 kg out of 100 kg initial dry pine. When the two liquors containing the hemicellulose sugars and the cellulose fines-derived hexoses were fermented for ethanol production, an ethanol yield of 6.8 kg was obtained.     

The lignol approach to biorefining of woody biomass to produce ethanol and chemicals

Processes that produce only ethanol from lignocellulosics display poor economics. This is generally overcome by constructing large facilities having satisfactory economies of scale, thus making financing onerous and hindering the development of suitable technologies. Lignol Innovations has developed a biorefining technology that employs an ethanol-based organosolv step to separate lignin, hemicellulose components, and extractives from the cellulosic fraction of woody biomass. The resultant cellulosic fraction is highly susceptible to enzymatic hydrolysis, generating very high yields of glucose (>90% in 12–24h) with typical enzyme loadings of 10–20 FPU (filter paper units)/g. This glucose is readily converted to ethanol, or possibly other sugar platform chemicals, either by sequential or simultaneous saccharification and fermentation. The liquor from the organosolv step is processed by well-established unit operations to recover lignin, furfural, xylose, acetic acid, and a lipophylic extractives fraction. The process ethanol is recovered and recycled back to the process. The resulting recycled process water is of a very high quality, low BOD₅, and suitable for overall system process closure. Significant benefits can be attained in greenhouse gas (GHG) emission reductions, as per the Kyoto Protocol. Revenues from the multiple products, particularly the lignin, ethanol and xylose fractions, ensure excellent economics for the process even in plants as small as 100 mtpd (metric tonnes per day) dry woody biomass input—a scale suitable for processing wood residues produced by a single large sawmill.     

Pretreatment of softwood by acid-catalyzed steam explosion followed by alkali extraction

A process for converting lignocellulosic biomass to ethanol hydrolyzes the hemicellulosic fraction to soluble sugars (i.e., pretreatment), followed by acid- or enzyme-catalyzed hydrolysis of the cellulosic fraction. Enzymatic hydrolysis may be improved by using an alkali to extract a fraction of the lignin from the pretreated material. The removal of the lignin may increase the accessibility of the cellulose to enzymatic attack, and thus improve overall economics of the process, if the alkali-treated material can still be effectively converted to ethanol. Pretreated Douglas fir produced by a sulfuric-acid-catalyzed steam explosion was treated with NaOH, NH₄OH, and lime to extract some of the lignin. The treated material, along with an untreated control sample, was tested by an enzymatic-digestion procedure, and converted to ethanol by simultaneous saccharification and fermentation using a glucose-fermenting yeast. NaOH was most effective at removing lignin (removed 29%), followed by NH4OH and lime. However, the susceptibility of the treated material to enzymatic digestion was lower than the control and decreased with increasing lignin removal. Ethanol production was similar for the control and NaOH-treated material, and lower for NH₄OH- and lime-treated material.     

Chemo-enzymatic production of fuel ethanol from cellulosic materials utilizing yeast expressing β-glucosidases

Ethanol was produced in a considerably high yield by fermenting hydrolyzates from cellulosic materials by means of a recombinant laboratory yeast expressing β-glucosidases. Tissue paper, cotton, and sawdust were hydrolyzed by two-step sulfuric acid hydrolysis to give mixtures containing glucose, cellobiose, and higher cello-oligosacc arides. After the cellulosic material was partially hydrolyzed with 80% sulfuric acid, the hydrolysis was continued with 5% sulfuric acid. Except for non-carbohydrate components, all constitutents in the hydrolyzates were fermented by the yeast that was preincubated in the medium that the plasmid encoded by the β-glucosidases gene was kept in the muliplicated yeast. A solution containing 4% hydrolyzates from paper was fermented to give as high as 1.9% maximum ethanol concentration and 70% ethanol conversion. Cotton also gave a similar result. Sawdust was converted into ethanol in approx 22% conversion. Accordingly, it was revealed that the β-glucosidases-expressing yeast can ferment the cello-oligosaccharides obtained by hydrolysis of cellulosic materials into ethanol. In addition, a hydrolyzate containing a high glucose proportion gave a high ethanol concentration in a short time.     

玉米秸秆连续氢解制备生物乙醇

目前由纤维素制生物乙醇的工艺主要由生物酶解法实现,但酶解法的效率低且经济性差;此外,生物酶发酵每产生1 mol乙醇的同时副产1 mol CO₂,导致原子经济性低.本文开发了一种通过连续氢解玉米秸秆纤维素转化为高浓度生物乙醇(6.1%)的工艺.首先使用绿色溶剂(80 wt%1,4-丁二醇)在不破坏木质素结构的前提下,提取玉米秸秆中的高纯度纤维素;再在浆态床反应器中通过Ni-WO_x/SiO₂催化剂将10 wt%纤维素水悬浮液转化为多元醇混合物(其中乙二醇占比58%).经过连续进样,纤维素质量浓度累积达30 wt%,乙二醇产物浓度达到17 wt%.随后,多元醇混合物被泵入固定床反应器进行选择性断C?O键反应,在改进的水热稳定Cu催化剂上转化为乙醇(转化率75%,选择性84%).纤维素转化为生物乙醇的过程反应至少包含四步基元步骤.首先,在高温水热环境中纤维素水解为葡萄糖,葡萄糖在WO_x表面经Retro-aldol反应C?C键断裂生成乙醇醛.随后,Ni催化剂将乙醇醛加氢为乙二醇,接着在固定床反应器上,乙二醇在NiAu修饰的Cu⁺/Cu⁰活性位点上选择性断裂C?O键生成乙醇.在乙二醇选择性氢解为乙醇过程中,催化剂Au-Cu-Ni/SiO₂表现出优异的水热稳定性和活性.XRD结果表明,金属Ni的引入有效地减小Cu纳米粒子的尺寸和增加Cu颗粒的分散,HRTEM图像更加直观的验证这一点.H₂-TPR结果发现,Ni的引入使CuO的还原温度提高了20℃,表明金属-载体的相互作用增强.同时发现,催化剂合成过程中氯金酸浸渍在还原后的CuNi/SiO₂催化剂的活性最高.紫外吸收光谱表明,溶液中的Au³⁺与催化剂表面的Cu发生置换反应,而非单纯的附着于催化剂表面.CO-DRIFTS结果表明,在Au修饰过的Cu-Ni/SiO₂表面使得Cu⁺-CO的红外吸收峰降低,主要是由于Au部分覆盖催化剂表面Cu⁺吸附位点造成的.XPS结果表明,Au的引入使得催化剂表面的Cu⁺/Cu⁰不容易被空气氧化,形成更为稳定的(Au-Cu⁺)-Cu⁰活性中心,增强了催化剂Cu活性中心的水热耐受性.本文提供了一条有竞争力的水相转化秸秆为高浓度生物乙醇的途径.     

Role of pretreatment and conditioning processes on toxicity of lignocellulosic biomass hydrolysates

The Department of Energy’s Office of the Biomass Program has set goals of making ethanol cost competitive by 2012 and replacing 30% of 2004 transportation supply with biofuels by 2030. Both goals require improvements in conversions of cellulosic biomass to sugars as well as improvements in fermentation rates and yields. Current best pretreatment processes are reasonably efficient at making the cellulose/hemicellulose/lignin matrix amenable to enzymatic hydrolysis and fermentation, but they release a number of toxic compounds into the hydrolysate which inhibit the growth and ethanol productivity of fermentation organisms. Conditioning methods designed to reduce the toxicity of hydrolysates are effective, but add to process costs and tend to reduce sugar yields, thus adding significantly to the final cost of production. Reducing the cost of cellulosic ethanol production will likely require enhanced understanding of the source and mode of action of hydrolysate toxic compounds, the means by which some organisms resist the actions of these compounds, and the methodology and mechanisms for conditioning hydrolysate to reduce toxicity. This review will provide an update on the state of knowledge in these areas and can provide insights useful for the crafting of hypotheses for improvements in pretreatment, conditioning, and fermentation organisms.     

In situ, rapid, and temporally resolved measurements of cellulase adsorption onto lignocellulosic substrates by UV-vis spectrophotometry

This study demonstrated two in situ UV-vis spectrophotometric methods for rapid and temporally resolved measurements of cellulase adsorption onto cellulosic and lignocellulosic substrates during enzymatic hydrolysis. The cellulase protein absorption peak at 280 nm was used for quantification. The spectral interferences from light scattering by small fibers (fines) and particulates and from absorptions by lignin leached from lignocelluloses were corrected using a dual-wavelength technique. Wavelengths of 500 and 255 nm were used as secondary wavelengths for correcting spectral interferences from light scattering and absorption of leached lignin. Spectral interferences can also be eliminated by taking the second derivative of the measured spectra of enzymatic hydrolysate of cellulose or lignocelluloses. The in situ measured cellulase adsorptions in cellulose and lignocellulose suspensions by these two spectrophotometric methods showed general agreement with batch sampling assayed by the Bradford method. The in situ methods not only eliminated tedious batch sampling but also can resolve the kinetics of the initial adsorption process. The measured time-dependent cellulase adsorptions were found to follow pseudo-second-order kinetics.     

Depolymerization of Organosolv Lignin over Silica-alumina Catalysts

E cient conversion of lignin to fine chemicals and biofuel become more and more attractive in biorefinery. In this work, we used a series of silica-alumina catalysts (i.e., SiO₂-Al₂O₃, HY, Hβ, and HZSM-5) to degrade lignin into arenes and phenols. The relationship between the catalyst structure and lignin depolymerization performance was investigated. The results showed that both acidity and pore size of the catalyst could in uence the conversion of lignin. In the volatilizable product, phenols were identified as the main phenolic monomers via gas chromatography-mass spectrometer. SiO₂-Al₂O₃ was the most effcient catalyst, giving 90.96% degree of conversion, 12.91% yield of phenols, and 2.41% yield of arenes in ethanol at 280℃ for 4 h. The Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance spectroscopy analysis demonstrated that deoxygenation and alkylation occurred in this process. The effect of solvents was also investigated and the results showed that ethanol was the most effcient solvent.     

Simulation analysis of the temperature dependence of lignin structure and dynamics

Lignins are hydrophobic, branched polymers that regulate water conduction and provide protection against chemical and biological degradation in plant cell walls. Lignins also form a residual barrier to effective hydrolysis of plant biomass pretreated at elevated temperatures in cellulosic ethanol production. Here, the temperature-dependent structure and dynamics of individual softwood lignin polymers in aqueous solution are examined using extensive (17 μs) molecular dynamics simulations. With decreasing temperature the lignins are found to transition from mobile, extended to glassy, compact states. The polymers are composed of blobs, inside which the radius of gyration of a polymer segment is a power-law function of the number of monomers comprising it. In the low temperature states the blobs are interpermeable, the polymer does not conform to Zimm/Stockmayer theory, and branching does not lead to reduction of the polymer size, the radius of gyration being instead determined by shape anisotropy. At high temperatures the blobs become spatially separated leading to a fractal crumpled globule form. The low-temperature collapse is thermodynamically driven by the increase of the translational entropy and density fluctuations of water molecules removed from the hydration shell, thus distinguishing lignin collapse from enthalpically driven coil-globule polymer transitions and providing a thermodynamic role of hydration water density fluctuations in driving hydrophobic polymer collapse. Although hydrophobic, lignin is wetted, leading to locally enhanced chain dynamics of solvent-exposed monomers. The detailed characterization obtained here provides insight at atomic detail into processes relevant to biomass pretreatment for cellulosic ethanol production and general polymer coil-globule transition phenomena.     

Synthesis of polyurea nanocomposite from industrial waste lignin: Classical curing of isocyanate by lignin-polyamine

Polyurea is an important class of polymer obtained through curing of the isocyanate and polyamine. Here lignin amine processed successive three-step reactions for the synthesis of nanostructure polyurea composite. Further the competence nature is found out by combining different lignin-polyamine with various di-isocyanate. In the first step, lignin was reacted with tosyl-chloride which modified the hydroxy function of lignin as a good leaving group. This reaction for tosylated lignin (Lignin-OTs) has 80% yield. Further lignin-OTs was reacted with four different polyamines replaced tosyl functional group by amine gives aminated lignin. Eventually, a classical reaction of aminated lignin and three different di-isocyanate yield a polyurea composite. A series of changes from lignin to its tosylation eventually to polyurea composite was pursued by the change in the functional group of lignin. The tosylated lignin was confirmed by IR absorption of the C-O peak at 1190 and 1365 cm^?1 and invisible peak absorption at 3500 cm^?1. The aminated lignin was confirmed by IR absorption at 3120 and 3430 cm^?1 for –NH. Thermal gravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to determine the product's thermal characteristics. Complete structural morphology of nanostructure lignin-polyurea composite was investigated by X-ray diffraction, FE-SEM and EDX.