过氧化物酶催化磺化木质素的工艺、机理及吸附特性研究

Lignin is a second biopolymer only to cellulose in plants. Alkali lignin coming from Alkali lignin is the main component of alkaline pulping black liquor which accounts for about 90% pulping waste liquor. However, the poorer solubility in water and lower molecular weight limit its practical application. The most commonly modified method to endow alkali lignin with good water solubility and better physicochemical properties is to introduce sulfonic group in alkali lignin by sulfonation and further increase its molecular weight via chemical polymerization. In chemical polymerization process need to add more chemical raw materials, and more important than the molecular weight of sulfonated alkali lignin is lower, which restricted the performance improvement and widely application of sulfonated lignin as macromolecule surfactant.. Alkali lignin was used as raw material in this project, and a novel technology to prepare sulfonated lignin with high molecular weight by mean of combining sulfonation with enzyme catalysis was investigated. Technological conditions were further optimized by studying the influence of reaction conditions on structural characteristics and microstructure of the product including its sulfonation degree and molecular weight. The relationship between molecular structure and adsorption characteristic of enzyme catalyzed sulfonated alkali lignin was established by investigating the adsorption characteristic of sulfonated alkali lignin at the solid-liquid interface. The interaction mechanism between sulfonation and enzyme catalysis, and enzyme catalysis mechanism of sulfonated alkali lignin were discussed by molecule simulation calculation and lignin model compounds with different molecular configurations and different attended modes. These results can also provide new ideas and technical support for developing green technology for polymers of lignin and high values-added lignin products.

木质素是植物中含量仅次于纤维素的聚合物，来自造纸制浆过程的碱木质素存在着亲水性差、分子量低等问题，通过磺化及聚合反应接入磺酸基、增大分子量是赋予其水溶性和优良物化性能最常用的方法。由于化学聚合反应过程中需加入较多的化工原料，得到的磺化木质素分子量也偏低、成为制约磺化木质素系高分子表面活性剂性能提高和广泛应用的瓶颈。.本项目以碱木质素为原料，首次采用磺化-酶催化相结合的技术路线制备高分子量磺化木质素，研究反应条件对产物磺化度、分子量等结构特征和微结构的影响，进一步优化工艺；研究其在固液界面上的吸附特性，建立酶催化磺化木质素的分子结构与吸附特性构效关系。采用具有不同结构特征和连接方式的木质素模型物和分子模拟计算阐明磺化-酶法催化相互影响机制及酶催化磺化木质素的作用机理。研究结果还可为木质素系高分子聚合物的“绿色”改性及工业木质素高附加值的应用提供新的思路和技术指导。

木质素是仅次于纤维素的第二大可再生资源。在制浆过程中植物中的木质素变成碱木质素溶解于黑液，成为黑液的主要成分。目前，超过90%的黑液浓缩后烧掉或直接排放，既浪费资源，又污染环境。要实现黑液的资源化高效利用必须对碱木质素进行改性以提高其性能，但由于碱木质素结构复杂、分子量分布宽、反应活性低等原因，导致对其进行改性并高效利用成为了一个世界级的难题。.针对碱木质素改性和黑液资源化高效利用中存在的科学问题和关键技术进行了深入研究，研究了碱木质素的预处理技术、预处理技术对碱木质素磺化反应活性的影响； 揭示磺甲基化反应对HRP催化聚合效果的影响；研究了辣根过氧化物酶对不同来源的碱木质素磺化反应活性和聚合程度的影响、辣根过氧化物酶对不同分子量级份的碱木质素磺化反应活性和聚合程度的影响；探索了辣根过氧化物酶改性磺甲基化碱木质素用于苯胺化学氧化聚合和导电纸的制备过程研究，揭示了木质素模型物的制备及酶催化活化磺化木质素机理。在此理论指导下，发明了高磺化度高分子量的木质素两亲聚合物的新技术。针对水泥、煤和农药等颗粒亲水性的不同及与木质素吸附作用力的差异，建立了制备木质素系混凝土高效减水剂、水煤浆分散剂和农药分散剂的技术路线与应用方法，成功制备了木质素系混凝土高效减水剂、水煤浆分散剂及农药分散剂等系列产品，其性能超过国内外同类产品，共开发了3个系列产品，在吉林华威友邦、广东瑞安、深圳诺普信等高新技术企业推广应用；大幅度提高了工业木质素利用的技术水平，促进了我国造纸制浆工业的节能减排和循环经济的发展。本成果共申请中国发明专利授权14件；发表SCI收录论文17篇；培养博士研究生3人，培养硕士研究生7人，获得中国发明专利优秀奖两件。