速生阔叶材预处理过程中半纤维素的解聚机制及其对后续木糖分离纯化的影响

The destroy process of physical and chemical structure of wood cell wall to promote the hemicellulose depolymerization was investigated in this proposal, using hardwood (such as Acacia wood) as raw material. Varied pretreatment technologies, such as ultrasonic, ionic liquid, micro-explosion, enzymes and hot water were employed based on the effect of vibrational dissociation of ultrasonic, softening and swelling of ionic liquid, mechanical fluffing of micro-explosion, enzymatic hydrolysis of enzymes and modification, as well as the hydrogen ion hydration under high temperature. The depolymerization mechanism of hemicellulose (xylan in particular) dissolving process during pretreatment process can be revealed by the changes of physical/ chemical and functional groups based on modern analysis of equipments including AFM, FTIR, NMR and GC-MS. Therefore, the pretreatment technology could be optimized. With the aid of enzyme controlling, activated carbon adsorption, ion exchange resin extraction, chromatographic classification and modern analysis equipment, the separation and purification of xylose with different degree of polymerization could be achieved, subsequently the composition and control regulation of xylo-oligosaccharide solution could be clarified. Sequentially, the influence of hemicellulose depolymerizaiton mechanism on the xylose separation will be figured out. The conclusion of this proposal could provide theoretical guidance on the high-value utilization of hemicellulose in hardwood, thus fulfilling pretreatment technology theory on promoting of hemicellulose depolymerizaiton process and separation/ purification system.

本项目以相思木等阔叶材为原料，采用超声波、离子液体、微爆、生物酶协同水热处理对木片进行预处理，利用超声波的振动解离作用、离子液体的软化润胀作用、微爆的物理疏松作用、生物酶的水解改性作用以及高温氢离子水合作用，破坏木质纤维结构，促进半纤维素解聚溶出。采用FTIR、NMR、GC-MS等现代仪器分析预处理过程中半纤维素聚糖（特别是聚木糖）的微观物理化学结构和功能基团的变化，了解预处理过程中半纤维素糖类的解聚溶出机制，优化确定预处理工艺条件。借助现代分析仪器分析预处理液中半纤维素降解产物，通过生物酶调控、活性炭吸附、离子交换树脂萃取、色谱分级技术来分离纯化预处理液中不同聚合度的木糖，弄清预处理液中低聚木糖的构成与调控规律，阐明预处理过程中半纤维素解聚对木糖分离纯化的影响机制，研究结果可为阔叶材半纤维素的高值化利用提供理论指导，丰富预处理技术促进木质纤维中半纤维素解聚和木糖分离纯化的科学理论体系。

本项目以相思木、桉木、杨木等阔叶材为原料，采用水热预处理、微波/酸组合预处理、超声波/水热组合预处理、离子液体/水热组合预处理、木聚糖酶/水热组合预处理以及低共熔溶剂预处理技术，研究探讨了预处理过程因素对阔叶材半纤维素组分解聚溶出效率的影响。利用酸的催化作用、超声波的振动解离作用、离子液体的软化润胀作用、生物酶的水解改性作用、高温氢离子水合作用以及低共熔溶剂的选择性溶解作用，破坏阔叶材木质纤维的物理化学结构，促进阔叶材半纤维素组分的解聚溶出。利用SEM、FTIR、XRD、TGA、NMR、GPC、XPS等现代仪器分析了预处理过程中阔叶材半纤维素聚糖的物理化学结构和功能基团的变化，明晰了预处理过程中阔叶材半纤维素聚糖的解聚溶出机制，优化确定了预处理工艺条件。通过氢氧化钙和活性炭吸附、木聚糖酶和漆酶调控、树脂选择性吸附萃取等处理技术分离纯化了预处理液中不同聚合度的低聚木糖，弄清了预水解液中低聚木糖的构成与调控规律，阐明了预处理过程中半纤维素解聚对木糖分离纯化的影响机制，建立了组合预处理技术促进阔叶材半纤维素组分分离纯化的新途径。研究结果为阔叶材半纤维素的解聚溶出和低聚木糖的分离纯化提供了理论指导，进一步丰富了预处理技术促进木质纤维组分清洁高效分离和功能化利用的科学理论体系。.项目研究成果获教育部科技进步一等奖1项，中国优秀专利1项；授权中国发明专利12项，澳大利亚革新专利2项；发表学术论文21篇，其中SCI收录论文11篇，EI收录论文1篇，中文核心期刊论文8篇；出版学术专著1部；培养9名硕士研究生完成学位论文和2名博士研究生进行课题研究；组织27人次参加国内外学术会议。