硫酸盐法溶解浆预水解过程中水溶性木素的产生途径及漆酶诱导聚合脱除机制

It is an effective approach to increase lignocellulosic material value by producing value-added product from pre-hydrolysis liquor of kraft- based dissolving pulp production process. However, the soluble and low molecular weight lignin and lignin-derived phenolic material was the major obstacle for the pre-hydrolysis liquor practical utilization. Therefore, the pre-hydrolysis liquor of kraft- based dissolving pulp production process was selected as raw material in this proposal, the soluble lignin in pre-hydrolysis liquor was isolated through extraction technologies such as liquid-to-liquid or liquid-solid-liquid method, subsequently subject to characterization. Afterward, the identified biological properties, formation and dissolving mechanism of soluble lignin from lignocellulosic material will be revealed. Furthermore, pre-hydrolysis factor was included to clarify the coordinating mechanism for lower lignin dissolving rate. Following, technologies such as biological treatment (laccase), physical adsorption and chemical reaction, as well as the synergy effect of these technologies will be employed to specific remove lignin from pre-hydrolysis liquor, the mechanism of laccase induced polymerization and lignin removal will be elucidated, as well as the fundament of enhanced lignin removal technologies. The recovered organic materials such as oligo/mono sugars, acetic acid, furfual during treatment will be determined for solidify the specific lignin removal during these treatments. Phenolic models will be employed to study the lignin change principal during treatment, thus the reaction mechanism of selective polymerization and lignin removed can be elucidated. With emphasis on the practical implication and fundamental understanding, the completion of the project will lay a solid scientific foundation for utilizing lignocellulosic material in high value model.

硫酸盐法溶解浆预水解液的高值化利用是提高木质纤维利用价值的有效途径，然而，水解液中存在的水溶性木素小分子及酚类物质是其高值化利用的主要障碍。本项目以木质纤维预水解液为研究对象，采用液-液/液-固-液萃取技术分离预水解液中的小分子木素并进行结构表征，揭示其生物特性及溶出机理，探究预水解因子对木素溶出率的调控机制；采用生物技术（漆酶）选择性分离木素，探索漆酶诱导水溶性木素的聚合脱除机制，并协同物理吸附/化学反应进一步分离木素，弄清协同处理的强化机制，同时探明目标有机物（半纤维素多糖/单糖、醋酸、糠醛等）在此过程中的反应行为；采用酚类模型物研究木素在处理过程中的变化规律，阐释高选择性分离木素的反应机理。研究结果可为木质纤维原料的高值化利用奠定坚实的科学基础，具有十分重要的现实意义和理论价值。

项目背景：预水解硫酸盐法溶解浆生产工艺实现了木质纤维原料中纤维素、半纤维素和木素的有效分离，是生物炼制的工业化原型。然而，水溶性木素组分的存在严重制约了预水解液中半纤维素组分的资源化利用，引起诸如共性沉淀、膜堵塞等问题。. 主要研究内容：本项目以杨木为原料，采用热水预水解制备预水解液，探索了木素溶出历程；通过分离表征预水解液木素，揭示了木素的结构特点和溶解机理；采用具有底物专一性的漆酶处理预水解液，以脱除溶解的木素组分，并建立了漆酶处理脱除木素的动力学模型；协同阳离子聚合物或物理吸附等手段强化木素组分的脱除，追踪目标有机物在处理过程的损失情况，评价了处理技术的脱木素选择性；采用假丝酵母发酵净化后的预水解液，成功制备出了木糖醇产品。. 重要结果及关键数据：预水解强度是调控木素溶出率的关键参数，溶解木素的结构表征证实预水解过程中木素间的β-O-4连接键发生了断裂，木素构型包含紫丁香基、愈创木基和对羟基苯基三种基本木素结构；漆酶催化处理是实现预水解液中溶解木素聚合脱除的重要步骤，漆酶用量和处理时间是控制木素脱除率的重要参数；漆酶协同阳离子聚合物或物理吸附等手段，可以进一步强化木素脱除；假丝酵母发酵净化后预水解液的木糖醇得率可达0.41g/g 木糖。经过三年的不懈努力和积极探索，共发表相关论文12篇，其中SCI期刊论文6篇，中文期刊论文4篇，会议论文2篇，获山东省教育厅自然科学三等奖一项。另外，在项目执行期间，项目负责人晋升为副教授；以本项目为基础，指导研究生一名，协助指导研究生四名，指导本科毕业生八名，其中一名获校级优秀毕业论文。. 科学意义：本项目较为系统的研究了木质纤维原料热水预水解过程中木素的溶出规律，表征了溶出木素的结构特点，阐明了生物技术在预水解液净化过程的作用规律和机理，建立了预水解液高值化利用的技术路线，为预水解液的高值化利用提供了理论和技术支持，项目成果可为林业资源组分分离和高值化利用提供科学依据。.