木质纤维素材料合成PHA预处理技术的研究进展

目的介绍木质纤维素材料的化学组成及结构,综述常见的木质纤维素材料预处理方法及其在合成包装材料聚羟基脂肪酸酯(PHA)方面的应用的研究进展。方法通过对国内外研究现状和研究成果分析总结,重点论述常见的木质纤维素材料预处理方法蒸汽爆破预处理、热水预处理、酸预处理、碱预处理、氨纤维爆破预处理、离子液体预处理、有机溶剂预处理等对木质纤维素材料糖化率的影响,及其在合成包装材料聚羟基脂肪酸酯(PHA)方面的应用。结果不同的木质纤维素材料和不同的预处理方法对最终产生的总糖含量及总糖内单糖种类和单糖占总糖质量分数产生很大的影响,其中将不同总糖(包含不同单糖种类和单糖占总糖的质量分数)作为碳源用于微生物发酵生产PHA,还会使形成PHA的单体及单体在PHA中的质量分数不同,形成具有不同性质的PHA,能广泛应用到包装领域中。结论关于国内外研究优化预处理和酶解工艺提高生成可发酵糖产量的研究有很多,热水预处理技术相较于其他预处理技术具有生产成本低、绿色环保等特点,因此,开发经济性好且适用于大规模工业化生产的热水预处理技术是今后值得关注的重点方向。     

延缓疏水膜润湿的原料液预处理方法研究

亲水化渗漏是疏水膜技术应用面临的关键性瓶颈问题之一,其产生的主要原因是水体中污染物中的表面活性物质对疏水膜的润湿作用.本文提出利用絮凝强化气-液萃取的预处理工艺以去除原液中的表面活性物质,以期减缓疏水膜的润湿进程.以十二烷基苯磺酸钠来模拟代表水体中腐殖酸等荷负电性表面活性物质,用聚偏氟乙烯中空纤维疏水膜进行减压膜蒸馏的润湿实验,探究预处理方法、预处理过程中絮凝剂的荷电性、种类以及用量对疏水膜材料亲水化渗漏的影响.结果表明：絮凝强化气-液萃取的预处理工艺可以有效去除原料液中的表面活性物质;阳离子型絮凝剂预处理效果优于阴离子型;有机絮凝剂预处理效果优于无机絮凝剂;当阳离子型聚丙烯酰胺加入量为12 mg/L时,表面活性物质十二烷基苯磺酸钠的去除率与未经絮凝预处理相比提高了17%.     

基于NaOH预处理的废纸纤维发泡材料工艺及配方研究

通过2种途径对废纸纤维发泡材料的工艺配方进行了优化,以获得性能更好的废纸纤维发泡材料。一是对废纸纤维原料进行NaOH预处理,研究了NaOH预处理对发泡材料性能的影响;二是基于NaOH预处理,采用微波加热发泡工艺改善了废纸纤维发泡材料的性能。结果表明:NaOH预处理较大程度上改善了废纸纤维发泡材料的发泡倍率、密度及缓冲性能。试验确定了废纸纤维预处理的最佳条件和基于NaOH预处理的废纸纤维发泡材料的最佳工艺配方。     

离子液体预处理木质纤维素的研究进展

预处理是木质纤维素生物炼制工艺中不可缺少的重要环节,但传统的预处理技术存在成本高、污染严重和效率较低等缺点。由于离子液体有熔点低、化学稳定性和热稳定性高、环境友好、可设计性等优势,被视为可替代传统试剂的新型绿色溶剂,近年来广泛应用于生物质预处理的研究中。介绍了离子液体在木质纤维素预处理中的研究现状,并通过分析、总结离子液体预处理中存在的问题,展望了离子液体预处理技术的发展前景。     

活化工艺对木质活性炭纤维结构和碘吸附性能的影响

以杉木为原料,经苯酚液化、熔融纺丝、固化处理后,CO2活化制备出木质活性炭纤维,利用扫描电镜、拉曼光谱、比表面积测定对其形态结构进行了表征,并研究了活化工艺因素对其碘吸附性能的影响。结果表明,木质活性炭纤维的表面平滑,断面呈圆形;500℃以上的木质活性炭纤维拉曼图谱都出现炭材料典型的D峰和G峰,且随着活化温度的提高,其石墨微晶尺寸La逐渐增大,R值逐渐减小;木质活性炭纤维的孔结构主要以微孔为主,其微孔率达到90%,只存在少许的中孔结构。随活化温度和活化剂用量的增加,木质活性炭纤维的碘吸附值明显增加,其收率随活化温度的升高呈现降低趋势;当活化时间增加到40min时,木质活性炭纤维的碘吸附值达到最大,而后降低。     

用廉价原料合成有机硅单体

日本化学技术研究所开发了用有机硅的原料二甲基二氯硅烷合成中副产的甲基氯二硅烷和廉价乙烯作原料,制备有机硅化合物(单体)的新工艺。据称用这种单体同钠进行反应,可以合成聚碳硅烷。可望用作光分解性聚合物和光致抗蚀剂、碳化硅纤维等。     

国内外纤维素乙醇技术进展

木质纤维素生产乙醇技术难度大，目前世界上还尚未实现工业化生产。主要有酸法和酶法两种工艺，与酸化水解等其他工艺相比，酶化水解具有反应条件温和、降解产物毒性低、糖得率高及设备投资低等优点。目前酶解纤维索乙醇面临三大技术瓶颈：①高效生物质预处理技术；②低成本纤维酶生产技术；③高耐受性的代谢C5产乙醇的微生物菌种。中国的纤维素乙醇技术在与国外合作的基础上，也有很大的突破。     

近红外光谱技术在木材化学属性方面应用的分析

因具有快速、无损、样品易于准备、适合于实际生产的在线检测等优点,近红外光谱技术在木材研究领域的应用越来越广泛。本论文阐述近红外光谱技术在木材木质素、纤维索、抽提物等化学属性预测、以及开展基于NIR技术的木质符合材料的原料属性的预测与分类研究具有重要的实际意义。     

原料预处理对BaTiO3压电陶瓷的物性影响

BaCO₃微粉原料通常由尺寸较大的棒状颗粒所组成, 这些棒状颗粒在一次球磨过程中由于不容易粉碎, 从而对经预烧、二次球磨所得到的BaTiO₃陶瓷微粉的化学组分的均匀性和颗粒度产生影响, 进而影响后序烧结制备的BaTiO₃陶瓷的微观组织结构和压电性能。本研究重点探讨了以BaCO₃和TiO₂为原料、通过固相反应途径制备BaTiO₃陶瓷时, 实施原料预处理对所制备的BaTiO₃压电陶瓷物性的影响。研究发现, 配料前对BaCO₃原料实施球磨预处理可明显地降低棒状颗粒的尺寸, 从而可获得颗粒度细化的BaTiO₃陶瓷微粉, 进而制备致密度更高和晶粒尺寸更小而压电性能更高的BaTiO₃陶瓷材料。研究中对BaCO₃微粉进行不同时间的球磨预处理, 然后制备钛酸钡陶瓷, 考察了其压电性能、介电性质、铁电性能和微观结构等物理性质。利用同样的BaCO₃微粉原料, 未经球磨预处理所制备的BaTiO₃陶瓷的压电系数d₃₃最高值为410 pC/N, 而实施合适的球磨预处理制备的BaTiO₃陶瓷的压电系数d₃₃最高值可达470 pC/N。     

木质纤维填充改性聚氨酯弹性体性能研究

为了改善聚氨酯弹性体拉伸和热稳定性能,本文以环氧树脂改性木质纤维,再填充至聚氨酯(PU)弹性体中制得生物基复合材料,采用万能试验机、扫描电镜和热分析仪分别对复合材料的拉伸性能、断面形貌和热稳定性进行测试分析。结果表明：与未改性填充木质纤维复合材料相比,经水性环氧和E-51环氧树脂改性木质纤维分别填充4wt.%和2wt.%时,复合材料的拉伸强度分别由18.2 MPa提高至22.4和23.7 MPa,断裂伸长率分别由898%提高至1 124%和2 269%。其中,采用2wt.%E-51环氧树脂溶液改性木质纤维填充2wt.%时,与未改性木质纤维相比,其拉伸强度提高了6.3%,断裂伸长率提高4倍以上,这是由于环氧改性木质纤维提高了木质纤维与树脂基体间的界面相容性。失重率为5%时,与未填充PU相比,复合材料的分解温度由269℃升高至279℃,提高了3.7%。填充木质纤维可提高PU拉伸性能与热稳定性。     

Particulate composites based on ionic liquid-treated oil palm fiber and thermoplastic starch adhesive

Pretreatment of lignocellulosic materials is a highly essential and critical task for the manufacturing of engineered composite panels. Recently, ionic liquids (ILs) have emerged as a promising green solvent for lignocellulosic biomass disintegration. In this work, the impact of IL pretreatment on the flexural and thermal properties of the thermo-molded biocomposite panels made from oil palm biomass residue and thermoplastic starch biopolymer as binder was studied. Oil palm fiber was pretreated with IL [emim][dep] (1-ethyl-3-methylimidazolium diethyl phosphate) and IL [bmim][Cl] (1-butyl-3-methylimidazolium chloride) prior to mixing with plasticized starch. The compounded mixture was then hot-pressed into composite panels. To understand the effect of IL pretreatment, lignocellulosic characterization, morphology, and thermogravimetric analysis of the untreated and treated fibers were performed. It was found that thermal stability of the oil palm biomass and the biocomposites was improved after IL pretreatment due to partial removal of hemicellulose and lignin from raw fiber. Moreover, pretreated biocomposites exhibited superior strength and modulus as compared to that of untreated sample as evidenced from flexural testing. The study plainly demonstrates that IL-assisted pretreatment could be an extremely attractive and clean technology for the efficient use of agro-based industrial waste in biocomposite field.     

Biomethane production kinetics of rumen pretreated lignocellulosic wastes

Clean Technologies and Environmental Policy - Bioenergy production from lignocellulosic biomass is challenging due to its complex structure. Therefore, a pretreatment is required before methane...     

植物纤维液化制备高分子材料研究进展

植物纤维经过热化学液化,进行适度降解,再与其他物质进一步反应,可以制备聚氨酯、环氧树脂、酚醛树脂等高分子材料。液化大大地改善了植物纤维原料的加工性能。综述了植物纤维液化加工工艺,液化机理及影响高分子材料性能的因素。     

Structure–morphology–mechanical properties relationship of some polypropylene/lignocellulosic composites

Natural lignocellulosic materials have an outstanding potential as thermoplastic reinforcement. Polypropylene composites were prepared using different types of lignocellulosic materials by melt blending of 70 wt% polypropylene (PP) and 30 wt% biomasses. The specimens were firstly evaluated for structural and morphological properties by infrared spectroscopy, X-ray diffraction, scanning electron and polarized optical microscopy. Depending on the biomass type, there were evidenced some particular shifts of the infrared bands and also crystallinity changes. An increase in crystallinity is explained by nucleating agent role of biomass. The morphological changes are directly related to variation in mechanical and rheological properties, an increase in Young modulus, melt viscosity and storage and loss moduli being recorded.     

Application of hydrothermal reaction to conversion of plant-origin biomasses into acetic and lactic acids

In this paper, some recent advances in our research on hydrothermal conversion of biomass into useful substances are presented. Here, we mainly focus on the production of acetic acid and lactic acid from carbohydrates including aldose, lignocellulosic biomass, and glycerin along with the discussion of some reaction mechanisms and the interaction between the main components of natural material, such as cellulose and lignin in lignocellulosic biomass. A large-scale continuous flow reactor system was also presented.     

木质纤维素类生物基材料研究进展

木质纤维素类生物质作为重要的可再生资源,不仅可以转化为能源及化工品,还可以合成相关的生物基材料。本文综述了以木质纤维素类生物质各组分为原料合成的生物基材料的种类、方法和应用,发现生物质是很好的化石材料替代品。直接将生物质各组分进行生物基材料合成会缩小其应用范围,运用化学改性方法对生物质各组分进行化学改性后再合成生物基材料,可以优化材料的一些性能,其中,基于生物质绿色、可降解和无污染的天然特性,在污水处理和替代相关石油基材料的原料方面其将发挥更重要的作用。     

Perspectives for the production of bioethanol from wood and straw in Austria: technical, economic, and ecological aspects

Bioethanol produced from lignocellulosic resources is a promising candidate for the replacement of fossil fuels. In this study, we aim to determine the perspectives to produce lignocellulosic ethanol in Austria. Technical, environmental and economic aspects are being considered. Thirteen biotechnological production concepts using the raw materials straw and softwood were established and simulated with the steady state flowsheeting software IPSEpro. Bioethanol production cost and greenhouse gas (GHG) emissions for each system were calculated based on mass and energy balances obtained from process simulation. The emission of GHGs along the entire bioethanol process chain (“from well to wheel”) are compared to two reference systems producing the same amounts of by-products. In all concepts, process heat and considerable amounts of the by-products electricity, heat, pellets, C5 molasses, or biomethane could be obtained from residual biomass. Compared to a reference system driven by fossil energy, GHG emissions can be reduced by up to 76%. The production cost of ethanol was found to between 0.66?€ and 0.94?€ per liter of gasoline equivalent. The type and amount of by-product influence technical, economic, and environmental performance significantly. Converting all straw and softwood available in Austria to ethanol would result in an annual production of 340?kt.     

X-ray computed microtomography and 2D image analysis for morphological characterization of short lignocellulosic fibers raw materials: A benchmark survey

Optimizing the performance of lignocellulosic fibers often requires relating mechanical behavior or morphological characteristics to microstructure. X-ray computed microtomography (X-ray CT), which provides 3D images with a high level of detail at both the micro- and macro-scales, may overcome these difficulties. This work provides a comparative analysis of the potential of X-ray CT (3D) and an office scanner (2D) for morphological characterization of lignocellulosic fibers. To this end, three specimens of lignocellulosic fiber materials obtained after the first decortication of the plant were retained. X-ray CT and 2D scanning correlations of sample diameter distributions are presented. The general aspects of the fibers diameter correlation are discussed. Image analysis was used to assess the potential and limitations of both the X-ray CT and 2D scanning methods based on the experimental work, and the main conclusions of the benchmark study are given in a table.     

Conventional low-density particleboards produced from Mauritia flexuosa and Eucalyptus spp. wood

Clean Technologies and Environmental Policy - The use of alternative raw materials to produce particleboards is an interesting strategy that adds value to lignocellulosic biomass and diversifies...