蔗渣碱抽提半纤维素及蒸煮的工艺研究

蔗渣含有丰富的半纤维素,制浆过程中,大部分半纤维素溶解到黑液中,为了提高这部分半纤维素的应用价值,本研究对蔗渣采用冷碱抽提半纤维素并进行低固形物蒸煮,探索合适的抽提蔗渣半纤维素的工艺。结果表明,当碱浓度在40~200 g/L,液比8∶1,抽提时间1 h,半纤维素的抽提率先随碱浓的提高而增加,当碱浓度在100 g/L时,半纤维素抽提率达到最大,随后开始缓慢下降。在抽提过程中,碱的消耗也随着半纤维素抽出的增加而增加;在总用碱量保持不变的情况下,碱浓度40~60 g/L抽提后蒸煮得率与传统蒸煮方法相比稍有下降,浆料中半纤维素含量也稍有下降,碱浓度80~100 g/L抽提后蒸煮得率有明显下降,并且浆料中半纤维素的含量很低;碱浓度60 g/L抽提后蒸煮的脱木素效率提高,在碱浓度80~100 g/L抽提时,因蒸煮用碱不够,蒸煮脱木素效率下降。为保障蔗渣浆的质量,可采用碱浓度40~60 g/L在蒸煮前抽提半纤维素。     

用木材生产生物燃料与纸浆

杨木木片硫酸盐制浆前,进行缓和的碱抽提处理,抽提出半纤维素用作生物燃料(生物乙醇),在温度90℃,NaOH 1～2M,液比1∶4条件下进行碱处理,不需要高压设备,每吨木片得到半纤维素40～50kg,经碱抽提后木片进行硫酸盐蒸煮,与未经碱抽提木片参照对比,纸浆得率基本相同,但是需要很好地控制碱抽提与硫酸盐蒸煮工艺条件,能缩短蒸煮时间和节省化学品用量。碱预抽提木片得到的硫酸盐纸浆中纤维素/半纤维素的比率稍高,导致纸浆的抗张指数稍有降低(约10%),但是纸浆白度较高且筛渣含量低,为使硫酸盐纸浆的质量和得率保持较高水平,采用缓和的碱预抽提,使半纤维素得率较低,而回收的半纤维素的浓缩和离析比木片自水解或稀酸水解回收糠醛更加容易。     

半纤维素热水预提取及其沉积对竹浆性能的影响

本论文以南方混合竹片为原料,考察了半纤维素热水预提取及其沉积对竹子制浆造纸性能的影响.结果表明:半纤维素热水预提取降低了蒸煮后纸浆的卡伯值,得率和耐破强度也相应降低,但纸页的撕裂强度提高;相对于未沉积半纤维素的纸浆,预处理后竹片制得的纸浆沉积半纤维素后,得率、卡伯值和机械强度均升高.在本实验条件下,热水预提取较佳的工艺条件为升温时间30min、保温时间30min、最高温度150℃;后续蒸煮的较佳工艺条件为用碱量16%,硫化度25%,最高温度165℃,升温90min,保温60min.     

预水解及液比对麦草制浆性能影响的研究

以水为介质对麦草进行蒸煮前的预处理,以最大限度的溶出麦草中的半纤维素,同时伴有少量的木素的溶出。在此基础上,提高在下一步蒸煮中麦草对碱溶液的吸收,提高制浆得率且减少制浆黑液的处理难度。研究表明:预水解的工艺条件为:水解温度150℃、水解时间1小时、液比1∶20。经此工艺条件处理后的麦草得率为83.05%,预水解残液高锰酸钾消耗值为1.005,pH值为4.8,还原糖含量为10.01%;经过AP-AQ法蒸煮得率44.55%,卡伯值21.38;相同蒸煮工艺条件下未水解的麦草浆得率为47.12%,卡伯值20.01。大液比有利于纸浆得率提高、蒸煮均一。     

对硫酸盐法制浆中碱抽提的探讨

为抽提出半纤维素并将其用作生物燃料,在硫酸盐法制浆前先对杨木木片进行了温和的碱处理。抽提在50～90℃下进行,不需要昂贵的加压反应装置,每吨木片可以回收40～50kg半纤维素,与常规蒸煮相比,抽提后的木片再经蒸煮也可以生产出等量的纸浆。预抽提需优化制浆工艺,从而缩短蒸煮时间,减少化学品用量。预抽提后的硫酸盐浆具有较高的纤维素／半纤维素比值,使抗张指数稍有下降（大约10％）,但可改进纸浆白度。此法虽然半纤维素得率低,但浆的性质和得率可保持在较高水平。回收的半纤维素比自动水解或稀酸处理后得到的糠醛更易浓缩和分离。     

几种提高蓝桉硫酸盐法制浆得率的方法

研究了蓝桉硫酸盐法制浆过程中提高原料中聚糖留着率的方法。添加蒽醌（AQ）的硫酸盐法制浆得率最高;添加尿素能减少聚糖的解聚（浆料黏度增加）,但对浆料得率无显著影响。在硫酸盐法蒸煮过程中,提早中断蒸煮,尤其是在快速、有选择性的大量脱木素段后便停止蒸煮,然后再进行氧脱木素是提高纸浆得率的有效方法。氧脱木素的得率损失明显低于硫酸盐法蒸煮过程终段（残余脱木素阶段）所造成的得率损失。在蒸煮的3个阶段,控制蒸煮液中OH？/HS？的用量也能提高纸浆得率,但纸浆得率随总用碱量减少而增加的结论是相比常规制浆条件下得到的。在常规硫酸盐法制浆中,活性碱用量对纸浆得率和黏度起决定性作用。低活性碱用量（14%）在提高纸浆得率的同时能保持纸浆黏度基本不变或略有上升,纸浆得率提高分别为纤维素和木素保留量提高所致。在制浆终段,纤维素组分的降低是纸浆得率下降的主要原因,而木聚糖组分基本保持不变,这是蓝桉半纤维素结构的特殊性所致。     

麦草碱法蒸煮中碱耗和木质素溶出的特征

本文借助切分蒸煮过程的手段,系统地研究了麦草碱法蒸煮中碱耗的分配,以及木质素的溶出特征,同时还通过溶出粗木质素的组成分析,对麦草碱法蒸煮中限制蒸煮得率的因素作了探讨,结果表明:(1)蒸煮用碱主要消耗于蒸煮前期酸性级分的中和,以及蒸煮前期溶出物的后续反应,作用于木质素降解反应的碱耗仅占很小的比倒:(2)麦草的碱易溶半纤维素和LCC的存在,以及LCC的抗碱性降解的特性,是限制其蒸煮得率提高的主要因素;(3)麦草碱法蒸煮后期脱木质素的进行,以物理形式自然溶出为主、化学降解为辅,其中木质素的溶出孔道对后期脱木质素的进行不具有控制作用。     

不同含髓率蔗渣蒸煮实验研究

本文对五种不同含髓率的蔗渣原料采用相同工艺的硫酸盐法蒸煮。考察了五种不同含髓率蔗渣原料进行蒸煮后的纸浆化学组分变化,分析了五种不同含髓率对蔗渣浆残碱和得率、蔗渣浆性能及纸浆打浆度和湿重的影响。实验结果表明,含髓率为13.3%的蔗渣在硫酸盐法蒸煮后化学组分(纤维素、半纤维素和木素含量)降解程度均较小,细浆得率高,且纸浆性能较好。     

关于竹材高得率浆的若干研究 第二部分——未漂浆(化学和半化学竹浆)的碱处理

在第一部分中研究讨论了在适宜条件下采用两段碱处理增加漂白和未漂白竹浆收获率的可能性。因为在漂白过程中,氯和氯化物除与木素作用外也与浆中已损坏了的纤维素和半纤维素起化学反应,使得得率进一步降低。得率的降低决定于两个主要因素:一是原未漂浆化学性质,另一个是漂白条件。如果原未漂浆含蒸煮过程剥离作用所损伤的纤维素和半纤维素化合物过多,那末漂白得率就降低较多。蒸煮过程的剥离作用能用多段的温和碱处理控制之。在这种情况下,硬浆再经过在较温和条件下的碱处理可使之变成比较软的浆。为了研究这种温和碱作用所生产的浆之特性,进行了下面的试验。     

在加有蒽醌的苏打法蒸煮中碳水化合物的稳定

苏打法蒸煮中加入蒽醌使纤维素和半纤维素中的还原糖端基氧化成糖醛酸端基,这种糖醛酸端基对末端碱降解是比较稳定的。在一定的木素含量下浆得率的提高是对脱木素的催化作用与对碳水化合物端基的氧化稳定作用的一种综合效果。     

玉米芯半纤维素提取、乙酰化改性及结构表征

以玉米芯为原料提取半纤维素,并对所提取的玉米芯半纤维素进行乙酰化改性。采用超声辅助碱法提取玉米芯半纤维素,浓硫酸（H₂SO₄）和单质碘（I₂）共催化玉米芯半纤维素进行乙酰化改性;采用红外光谱（IR）、热重分析（TGA）和核磁共振光谱（NMR）对玉米芯半纤维素及其乙酰化产物进行表征。玉米芯半纤维素得率和提取率分别为33.7%和81.0%,其中半纤维素含量为85.3wt%,乙酰化产物产率和取代度（DS）分别为84.6%和1.27。超声辅助有效缩短了碱法提取玉米芯半纤维素的时间,且玉米芯半纤维素得率和提取率均得到提高。H₂SO₄和I₂是半纤维素乙酰化改性的高效共催化体系,IR和NMR结果表明半纤维素被成功改性,改性产物中存在乙酰基,TGA分析表明乙酰化产物热稳定性增加,且DS值适中,有望进一步用于制备可生物降解的食品包装材料。     

响应面法优化芝麻蛋白的提取工艺

以脱脂芝麻渣为原料,对芝麻蛋白采用碱提酸沉法进行提取。试验考察了温度、加碱量、提取时间以及液固比对芝麻蛋白提取率的影响。结果表明,芝麻蛋白的最佳提取工艺条件为温度74.6 ℃,加碱量18%,提取时间291 min,液固比25∶1（mL∶g）,在此条件下,芝麻蛋白质提取率为75.59%。蛋白纯度达到69%,含有17种氨基酸,其中谷氨酸含量最高,为14.99%。     

大麻纤维高温闪爆联合脱胶技术

研究大麻纤维高温闪爆联合脱胶工艺,讨论高温闪爆联合处理条件对大麻纤维性能及组分分离效果的影响。用FTIR、SEM对联合脱胶后大麻的表面形态结构和化学成分进行分析。研究发现:半纤维素和木质素的含量分别下降了81152 %和86168 % ,纤维素比率明显提高,达到大麻纤维脱胶的目的;工艺中高温蒸煮温度、用碱量、闪爆前处理、闪爆压力及温度,保压时间及闪爆次数等是影响纤维分离的重要因素;高温蒸煮及预浸处理对纤维的溶胀作用有利于闪爆条件的降低     

软化方法对食用槟榔品质的影响

采用煮、蒸、碱、酸、微波、酶和反复冷冻7种方法软化槟榔,以未软化的样品为对照,研究软化方法对食用槟榔的咀嚼性、碎渣性、槟榔碱含量、TPA(质构分析)测试、五针穿刺测试和味觉指标的影响。结果表明:蒸(88.1分)、碱(85.3分)和微波(83.2分)的咀嚼性得分最高;对照(84.7分)、煮(80.7分)和冷冻(78.8分)的碎渣性得分最高;对照(4.90%)、冷冻(4.49%)、碱(4.17%)和酸(4.14%)的槟榔碱含量较高;从TPA测试结果看,酶、微波、蒸和碱的软化效果最好;从五针穿刺测试结果看,微波、碱、酸、酶和蒸的软化效果最好;从味觉指标分析看,煮和蒸可以去酸、苦、涩,但是会降低鲜味,微波和冷冻对风味几乎没影响,碱可以去酸、增咸和增鲜,但是会带来苦和涩,酸会给槟榔带来酸和苦,酶对去酸和涩有轻微作用。综合来看,蒸、微波、酶和碱处理具有软化效果显著、对风味影响较小等特点,更适合应用于实际生产。     

Standardization of ginseng processing for maximizing the phytonutrients of ginseng

This study was designed to optimize the process conditions, such as steaming, drying, and extracting, for obtaining the maximum content of prosapogenin (Rg3, Rg2, Rh1, and Rh2) from red ginseng, which has antitumor and anti-cancer properties. The steaming process was performed in an autoclave and the drying and extracting processes were done in dryer and heat extractor, respectively, and content of each prosapogenin was analyzed by HPLC. In the steaming process, prosapogenin values did not show any significant increase at 80 or 90°C, but tended to increase sharply as the steaming period became longer at 100°C, and the maximum value was obtained at 100°C with 6 h of steaming without any significant difference between local Gyeonggi areas. Drying red ginseng at 70°C for 24 h was the optimal condition to enhance prosapogenin extraction without affecting the quality. Maximal crude saponin and prosapogenin contents were obtained using 70% ethanol as the solvent at 70°C in the extracting process. Using these standardization processes such as steaming, drying, and extraction, maximum prosapogenin values could be obtained at ginseng factories.

     

Extraction, Purification, and Applications of Hemicellulose

In addition to cellulose and lignin, hemicellulose is an important biomass material. Recently, hemicellulose and its derivatives and materials have attracted increasing attention owing to their unique structures, improved properties, and promising application potential, and many reports on the extraction, isolation, and modification of hemicellulose are currently available. We summarized the recent developments of hemicellulose and its derivatives and materials by focusing on the extraction, purification, and modification of hemicellulose. The synthesis of hemicellulose-based derivatives and materials was also reviewed. Various methods of extracting, isolating, and modifying hemicellulose were discussed. Remaining challenges related to hemicellulose extraction, purification, and application were mentioned, and directions for further research on hemicellulose were proposed.     

木聚糖酶处理中碳水化合物的降解及对木素溶出性能的影响

研究了木聚糖酶处理中碳水化合物的降解及对木素溶出性能的影响,结果表明,木聚糖酶处理中纤维表面、纸浆中半纤维素被降解溶出,LCC结构被降解。木聚糖酶处理也溶出蜜二糖和塔罗糖。木聚糖酶预处理能加强后续碱抽提中大分子质量木素的溶出。     

Green and Effective Ammonium Carbonate-assisted Process for Drying Hemicellulose Obtained through Alkali Extraction of Bleached Bamboo Kraft Pulp

Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.     

Effect of extraction conditions on hemicellulose yields and optimisation for industrial processes

Hemicellulose is a valuable component of agro‐food industrial wastes and used in various areas such as drug manufacture and food industry for encapsulation and emulsification. In this study, effects of raw material type, particle size, and extraction conditions (alkaline concentration, temperature, time) and methods (direct alkaline extraction, alkaline extraction after component removal and acidic extraction method) on hemicellulose yields were investigated. Sugar beet pulp and corn wastes were used as raw material. The alkaline method resulted in 40.2% pure extracts, while the acidic method gave only 27.4% purity in the same extraction conditions. The optimal extraction conditions were found as 30 °C temperature, 10% alkali (NaOH) and 24 h time (64.3%). It was also observed that removal of constituents such as fat, protein, starch and soluble sugar increased the purity of hemicellulose from 40.2% to 58.2% at the same conditions. The results indicated that using both low alkaline concentration and low temperature allows to recover higher‐quality extracts.     

黄酮类化合物提取工艺研究

综述了天然黄酮类物质的9种提取工艺，分别是水提法，碱性水或碱性稀醇提取法，有机溶剂提取法，微波法，超声波法，酶解法，大孔树脂吸附法，超滤法，超临界萃取法。