低共熔溶剂在木质纤维生物质预处理领域的研究进展

低共熔溶剂（Deep Eutectic Solvents,DESs）由于具有熔点低、溶解性好、制备成本低、绿色无毒、可生物降解和电化学窗口宽等特性而被视为新型绿色溶剂，在木质纤维生物质预处理领域展现出广阔的应用前景。本文综述了DESs在预处理木质纤维生物质、制备纳米纤维素、高效提取分离木质素与半纤维素领域的研究进展，并指出了DESs在目前研究发展中存在的不足及其未来的研究方向，以期为进一步研究提供理论依据。     

基于熔盐水合物预处理的木质纤维生物质精炼研究进展

熔盐水合物（molten salt hydrate,MSH）具有易制备、成本低、沸点高、蒸汽压低、环境友好等特点，在木质纤维生物质精炼领域展现出广阔的应用前景。本文主要综述了MSH预处理技术在木质纤维生物质组分分离及高值化利用方面的研究进展，并总结了MSH预处理技术在目前木质纤维生物质精炼研究发展中存在的不足及未来的发展方向，以期为木质纤维生物质的精炼研究提供借鉴。     

基于低共熔溶剂预处理的木质纤维素生物质精炼研究进展

低共熔溶剂(DES)是一种新型的绿色溶剂,具有制备简单、成本低廉、生物相容性好、可循环再生、分子极性强和可设计性等特点,在生物质精炼、催化转化及功能材料构筑等领域展现出良好的应用前景。本文结合DES预处理技术在木质纤维素生物质精炼领域的最新研究报道,重点综述了不同组成和性质的DES采用单独或协同预处理分别对纤维素、半纤维素及木素三大组分的溶解机理、影响因素及分离效果,分析并展望了基于DES预处理后木质纤维素各组分的功能化及高值化利用的优势、不足及发展现状,以期为采用新型绿色溶剂促进木质纤维素生物质精炼研究与应用提供新的借鉴。     

木质纤维素功能材料的研究进展

木材独特的多层级结构、优异的各向异性结构、良好的力学性能和微纳米通道,赋予其一系列非凡的性能,为功能材料的设计提供了更多可能。为提高木质纤维素资源的利用率和高值化转化,基于木质纤维素自身结构和理化性能,概述了木质纤维素在系列功能材料领域的发展,总结了结构设计及调控对木质纤维素功能材料性能的影响,综述了其在结构调控材料、生物降解塑料、纳米流体材料、仿生生物材料及再生纤维素纤维方面的研究进展,指出其所面临的挑战以及未来发展方向,以期为木质纤维素的高值化转化和拓展其现代化应用提供理论参考。     

低共熔溶剂在木质纤维素预处理中的应用

低共熔溶剂（DES）在木质纤维素预处理中已得到了广泛应用,取得了重要的研究进展。本文主要介绍了DES的物理性质及其对木质纤维素的作用机理,综述了DES在木质纤维素预处理领域（木质素的分离,纤维素的纳米分散、衍生化及其溶解,半纤维素降解转化）的应用研究进展,总结并展望DES在木质纤维素预处理应用中面临的机遇和挑战。     

木质纤维素预处理方法研究进展

木质纤维素是自然界中最丰富的生物质可再生资源,对木质纤维素进行预处理,可以有效降低底物的结晶度,提高木质纤维素利用率,提升其附加值。本文对传统木质纤维素预处理技术和新型预处理技术进行了综述,分析比较了不同预处理技术的利弊,并对今后木质纤维素预处理技术的发展提出了展望,以期为探索新型预处理降解技术提供参考。     

热水预处理对木质纤维素生物质炼制的影响

阐述了热水预处理在木质纤维素生物质炼制过程中的目的与作用。介绍了近年来木质纤维素生物质热水预处理的部分研究成果与进展,并着重总结了热水预处理对木质纤维素生物质化学组分、微观结构和酶水解效率的影响,以期对木质纤维素生物质热水预处理研究和工业化应用提供借鉴。     

不同类型深度共熔溶剂预处理的甘蔗渣酶解效率差异

为了探索深度共熔溶剂(DES)预处理生物质的机制,本文分别设计了五种以氯化胆碱为氢键受体(HBA)和以苹果酸为氢键供体(HBD)的DESs来预处理甘蔗渣,分析HBD和HBA对甘蔗渣组分和酶解效率的影响。在氯化胆碱为HBA的DESs中,乳酸-氯化胆碱(LC)的预处理效果和酶解效率最好,所得甘蔗渣残渣的纤维素含量为72.92%,纤维素降解度为60.43%,葡萄糖收率为56.90%;而在苹果酸为HBD的DESs中,苹果酸-氯化胆碱的预处理效果最佳,木聚糖和木质素去除率均为最高,纤维素降解度为43.35%,葡萄糖收率为38.00%。研究结果证明DES的HBA和HBD的作用皆不可忽略,其分子间氢键作用强度与其对生物质的解构能力负相关。并发现甘蔗渣的木聚糖去除率与氢键受供体的p Ka值具有一定的相关性;纤维素降解度与木聚糖去除率正相关,而与木质素去除率无关。此外,在一定范围内,DES分子间的氢键作用强度、DES与甘蔗渣的氢键缔合作用与预处理温度和时间有相关性。本研究为用于生物质预处理的新型DES的设计提供了一定的理论参考。     

我国木质纤维生产乙醇的研发态势与科技需求

以2008—2014年我国学术期刊发表的研究文献为对象,从比重视角统计分析了我国木质纤维乙醇在原料选择、原料预处理、水解糖化和发酵等方面的研发现状和趋势,指出了我国木质纤维乙醇研发中存在的主要问题,并阐述了在原料收集与预处理、微生物菌群、水解和发酵、废弃物处理、全系统优化等重点领域的科技需求。     

北京地区废弃木质材料热裂解液化利用可行性及建议

面对能源匮乏、经济发展和环境保护三重压力,北京发展废弃木质材料能源化、高值化利用技术十分必要。本文首先介绍了北京地区废弃木质材料资源及利用现状,然后探讨了北京地区废弃木质材料热裂解液化利用的可行性,最后提出了建设示范工程的初步建议。     

木质纤维原料的苯酚液化

在苯酚中,木质纤维原料可以液化,原料中的木质素、纤维素和半纤维素转将化为具有反应活性的液态物质,这是一种具有生物降解性能的新型高分子材料.文章综述了木质纤维原料苯酚液化的发展状况,包括苯酚液化的方法、液化机理及各种木质纤维原料苯酚液化的应用.     

低共熔溶剂提取植物活性成分的研究进展

低共熔溶剂对酚类化合物和多糖等植物活性成分的提取及其影响因素,以期为低共熔溶剂提取植物活性成分的进一步研究和利用奠定基础。     

Enzymatic saccharification of biologically pretreated Pinus densiflora using enzymes from brown rot fungi

Enzymatic saccharification of lignocellulosic biomass was performed using culture filtrates of brown rot fungi including Gloeophyllum sepiarium, Fomitopsis pinicola, and Laetiporus sulphureus. Biological treatment with white rot fungi was used as pretreatment prior to enzymatic saccharification. Endoglucanase, beta-glucosidase, xylanase and cellobiohydrolase activities were determined from concentrated culture filtrates of the brown rot fungi. L. sulphureus has the highest endoglucanase, beta-glucosidase, and xylanase activities, and F. pinicola has the highest cellobiohydrolase activity. When enzymes from L. sulphureus were used along with the lignocellulosic biomass pretreated with Stereum hirsutum as the carbon source, the total sugar yield was 11.36 mg/0.25 g of dry weight biomass, with the highest activities of cellulase and hemicellulase. In order to increase the sugar yield, the enzymes from L. sulphureus were mixed with those from F. pinicola, which showed high cellobiohydrolase activity. This caused an increase in the sugar yield from 11.36 mg to 15.22 mg. When temperature was increased to 50 degrees C, the total sugar yield increased to 17.74 mg for the same reaction time. The crystallinity of lignocellulosic biomass decreased from 68.4% to 60.2%, when lignocellulosic biomass pretreated with S. hirsutum was hydrolyzed using enzymes from L. sulphureus.     

不同类型低共熔溶剂预处理对玉米秸秆酶解效率的影响

为探索不同类型低共熔溶剂（DES）预处理提高生物质酶解效率的机制,该研究选取两类DES即酸性（氯化胆碱(ChCl)-乳酸(Lac)、甜菜碱(B)-Lac）和碱性DES（ChCl-乙醇胺(M)、ChCl-N-(2-羟乙基)乙二胺(CN-2)）预处理玉米秸秆,对比研究不同酸碱性的DES对玉米秸秆组分和酶解效果的影响。研究表明碱性DES预处理和酶解效果较好,多糖含量从未处理时51.59%提高到81.33%~83.36%,木质素去除率71.35%~89.72%,多糖降解较为完全。红外光谱显示预处理中大量木质素和半纤维素的链接键发生断裂,糖苷键吸收峰显著增强;X-射线衍射表明玉米秸秆结晶度数值由32.99增至处理后的53.60,但晶体结构未改变。与酸性DES相比,碱性DES处理后外观色泽较浅,扫描电镜显示与未处理相比,预处理后的纤维疏松且粗糙。两类DES均是高效的预处理溶剂,碱性DES除本身碱性外,还可选择性的去除木质素,破坏半纤维素和木质素间链接键,纤维素与酶的接触面增大,从而酶解效率显著提高。该研究为生物质预处理新型DES溶剂的设计和选择提供一定的理论参考。     

响应面法优化超声辅助低共熔溶剂提取山楂总黄酮工艺

考察超声辅助低共熔溶剂提取山楂总黄酮的效果,优化提取工艺参数。首先制备10种不同组分的低共熔溶剂提取山楂总黄酮,从中筛选出得率最高的低共熔溶剂。然后通过单因素实验,确定低共熔溶剂的含水量和组分比例,并利用响应面法优化超声辅助低共熔溶剂提取山楂总黄酮的提取温度、液料比及超声时间,获得最佳提取工艺。结果显示,含50%水的丙三醇/氯化胆碱（摩尔比3:1）低共熔溶剂是提取山楂总黄酮的最佳溶剂,优化的工艺条件为:液料比42 mL/g、超声时间21 min、提取温度72 °C。在此条件下,山楂总黄酮、芦丁、牡荆素、金丝桃苷、槲皮素的得率分别为7.72%、0.24%、0.33%、0.18%、0.27%,均优于传统的醇提法。在浓度为0.1 mg/mL时,山楂DESs提取物DPPH清除率为86%,高于山楂甲醇提取物,其抗氧化活性增强。因此,超声辅助低共熔溶剂可有效提升山楂总黄酮得率,为山楂资源的开发利用提供科学依据。     

Hydrothermal Pretreatment of Lignocellulosic Materials for Improving Bioethanol Production

With the continued depletion of non-renewable energy resources,it is essential to seek new methods of harnessing clean and renewable energy.In this regard,second-generation bioethanol derived from lignocellulosic biomass has attracted increasing attention in recent years.The choice of the pretreatment method of lignocellulose is critical to the subsequent bioconversion processes.Compared with other conventional chemical pretreatment methods,hydrothermal pretreatment is a simple,low-cost,and economically feasible process that requires water as the only reagent.This paper reviews the research efforts that have been made toward hydrothermal pretreatment of lignocellulosic biomass and focuses on the transformations involving cellulose,hemicellulose,and lignin during this process.     

纤维乙醇发酵和脱水工艺的发展前景

纤维乙醇发酵菌株的选育影响糖的利用率,特别是木糖利用率的提高有利于乙醇产量的增加。作者综述了纤维乙醇发酵中发酵菌株、发酵工艺和脱水工艺的研究现状,分析它们的优缺点,并提出了未来纤维乙醇发酵和脱水工艺的研究方向。     

Yeast derived from lignocellulosic biomass as a sustainable feed resource for use in aquaculture

The global expansion in aquaculture production implies an emerging need of suitable and sustainable protein sources. Currently, the fish feed industry is dependent on high‐quality protein sources of marine and plant origin. Yeast derived from processing of low‐value and non‐food lignocellulosic biomass is a potential sustainable source of protein in fish diets. Following enzymatic hydrolysis, the hexose and pentose sugars of lignocellulosic substrates and supplementary nutrients can be converted into protein‐rich yeast biomass by fermentation. Studies have shown that yeasts such as Saccharomyces cerevisiae, Candida utilis and Kluyveromyces marxianus have favourable amino acid composition and excellent properties as protein sources in diets for fish, including carnivorous species such as Atlantic salmon and rainbow trout. Suitable downstream processing of the biomass to disrupt cell walls is required to secure high nutrient digestibility. A number of studies have shown various immunological and health benefits from feeding fish low levels of yeast and yeast‐derived cell wall fractions. This review summarises current literature on the potential of yeast from lignocellulosic biomass as an alternative protein source for the aquaculture industry. It is concluded that further research and development within yeast production can be important to secure the future sustainability and economic viability of intensive aquaculture. © 2016 Society of Chemical Industry     

Mercerizing Extraction and Physicochemical Characterizations of Lignocellulosic Fiber from the Leaf Waste of Mikania micrantha Kunth ex H.B.K

ABSTRACT

Invasive plants can grow rampantly and spread fast in large amount, which can be economically invoked for generating value-added products. In this study, lignocellulosic fiber was extracted from the leaf waste of a luxuriant invasive plant, Mikania micrantha Kunth-ex H.B.K. by mercerization process. After the alkaline treatment, the lignocellulosic biomass remained at 38.54% resulting from the large removal of extractive impurities. The lignocellulosic fraction in the mercerized leaf fiber was improved from 56.59% to 83.96%. The chemical composition analysis showed the cellulose fraction was increased by 11.17% while the hemicellulose and lignin fractions were found to be decreased by 4.89% and 6.28%, respectively. The FT-IR and TGA results further affirmed the change in chemical composition of the lignocellulosic fiber. Furthermore, an increase in cellulose fraction raised the fiber crystallinity index from 11.0% to 36.7%. The SEM study revealed that the surface morphology of lignocellulosic fiber changed from smooth surface into rough corrugated ridges, which affirmed the increase in crystallinity, resulting from the removal of wrapped cementing materials. In subsequent, the lignocellulosic fiber exhibited more pervious to water attack with an increase in moisture absorption from 119.22% to 410.19%.