【作者】 王娟；

【导师】 刘玉；

【作者基本信息】 山东轻工业学院 ， 林产化学加工工程， 2010， 硕士

【摘要】 在资源、能源日益紧张的今天,充分利用现有的造纸用植物纤维资源,研究原有纸制品的纤维原料性能,同时改善其性能对发展我国造纸工业具有举足轻重的作用。在制浆造纸工业中纸张性能的改善一般通过添加湿布化学助剂来实现,但近年来酶以其对纤维素、半纤维素和木素的特定作用成为研究的热点。漆酶是一种木素降解酶,在某些具有传递电子能力的介体和氧气存在下,能够对木素发生氧化降解。高得率纸浆的木素含量高,纤维的表面被一层木素覆盖着。这种表面性能导致了纤维柔韧性较差,纤维之间的结合性能较差,因而成纸具有物理强度较差、白度较低、容易返黄等缺点,从而限制了高得率纸浆的进一步应用。因此针对高得率纸浆高木素含量的特征,对其进行改性,在使其保持自身优点的同时改善浆料的性能成为人们关注的焦点。本论文利用漆酶和漆酶/介体(LMS)体系对杨木碱性过氧化氢机械浆进行改性并对纸浆中残余木素结构变化进行了详细的研究。利用漆酶和漆酶/介体体系改性杨木碱性过氧化氢机械浆纸浆的最佳工艺条件为:在通氧气的条件下,漆酶用量2u/g,酶作用时间60min,温度60℃,浆浓4.0%,pH值5.0,介体用量0.5%。在此条件下进行改性,改性纸浆白度较对照浆均有所降低,抗张指数和撕裂指数均有所增加。利用FQA、ESEM等分析技术对对照浆、漆酶改性纸浆和漆酶/介体体系改性纸浆进行纤维表面性能分析。纸浆纤维长度、粗度分析结果表明,漆酶对纸浆中纤维有较大的影响,环境扫面电镜分析结果表明,漆酶改性对纸浆纤维表面有较大的作用。采用酶解-弱酸解两段法分别从对照浆、漆酶改性纸浆及漆酶/介体体系改性纸浆中分离出纸浆残余木素试样。通过凝胶渗透色谱方法对木素试样进行木素分子质量分布的表征。表征结果显示,APMP一段纸浆经过漆酶单独处理后,纸浆中残余木素的分子质量增加,且增加幅度远大于经LMS改性后残余木素分子质量的增加幅度。二段纸浆经过漆酶单独处理后,纸浆中残余木素的分子质量变化与一段纸浆相似。APMP两段原纸浆中残余木素的多分散性较小,经过漆酶和漆酶/介体体系改性后多分散性增加。利用红外FTIR和磷谱核磁共振技术,对木素结构中基团进行定性、定量分析。通过31P-NMR谱图对APMP纸浆分析,得出漆酶和漆酶/介体体系改性过程中木素结构中功能基团含量的变化规律。在漆酶改性纸浆过程中,APMP一段纸浆残余木素中脂肪羟基含量略有增加,羧基降低,总酚羟基含量下降,缩合酚羟基、紫丁香基酚羟基、愈创木基和脱甲基酚羟基和对酚羟基含量均有所降低。APMP二段纸浆残余木素中脂肪羟基含量、总酚羟基含量和羧基含量均下降,缩合酚羟基、紫丁香基酚羟基、愈创木基和脱甲基酚羟基和对酚羟基含量均下降。在漆酶/介体体系改性纸浆过程中,APMP一段纸浆残余木素中脂肪羟基含量略有降低,羧基含量有所降低,总酚羟基含量明显下降,缩合酚羟基、紫丁香基酚羟基、愈创木基和脱甲基酚羟基和对酚羟基含量均下降。APMP二段纸浆残余木素中脂肪羟基含量略有增加,羧基含量下降,总酚羟基含量明显降低,缩合酚羟基、紫丁香基酚羟基含量均降低,愈创木基和脱甲基酚羟基和对酚羟基含量均不变。更多还原

【Abstract】 Nowadays, shortage of raw materials and energy is becoming more and more serious to pulp and paper industry. There has been an increasing trend towards more efficient utilization of raw materials by fiber modification. A wide range of chemicals have been developed to improve paper properties. In addition, enzymes have received significant attention for their highly specific effects on cellulose, hemicellulose, lignin and/or extractives. Laccase is a multicopper oxidase enzyme catalyzing the oxidation of lignin in the presence of mediater and oxygen.Lignin-riched fiber surface of mechanical pulp can lead to poor flexibility、low strength of fibers and low brightness and return to yellow easily. Therefore, the mechanical pulp can not completely replace the chemical pulps to produce paper with high quality. It is needed to modify the chemical pulps in order to expanding its scope of application, while their own advantages are kept. In this paper, we studied the lignin structure changes in detail of poplar alkaline perxide mechanical pulp, which modified by the laccase and laccase/mediator system .It was found that the optimum conditions of the two pulps of poplar alkaline peroxide mechanical pulp modified by laccase and laccase/mediator were:pH 5,temperature 50℃,pulp consistency4%, reaction time 60min,the optimum charge of laccase were 2u/g , O2 and the charge of mediator were 0.5%. The results showed that the brightness of the modified pulp were decreased compared to the control pulp, while the tensile index and the tear index were increased.Physical properties of paper were studied by FQA and ESEM.The result showed that the laccase had a great influence on the fibers.Especially on the fiber surface of the pulp, the average length and coarseness of modified fibers changed. Some surface lignin was dissoved after enzyme treatment, while the brightness and strength of paper were both increased. Infrared spectra show that the degradation of lignin happened and part of lignin dissolved during the modification process .The sample of isolated lignin from the control pulp and the modified pulp by the laccase and laccase/meditor by the two-stage method of enzyme-mild acidic hydrolysis solution.The molecular weight distributions of lignin were studied through GPC analysis. The results indicated that: the number average molecular weight of the residual lignin from the first stage of APMP both decresed after the modifiction by laccase and LMS, while the mass average molecular weights both increased. The change of the average molecular weight of the residual lignin of the two stage pulp were similar with the first stage pulp. The despersivity of lignin were both increased obviously after the modification by laccase and LMS.The functional groups of all lignin samples from APMP pulps and modified pulps by laccase and LMS were studied using infrared spectroscopy FTIR and phosphorus nuclear magnetic resonance, qualitatively and quantitatively.During the modification of the first-stage APMP with laccase, the content of aliphatic OH (A-OH) increased, while the contents of COOH and total phenolic OH (T-OH) decreased. The contents of the condensed phenolic OH (C-OH)、syringyl phenolic (S-OH)、guaiacyl and dementhylated OH (G-OH) and p-hydroxyl-phenyl OH (p-OH) decreased in the residual lignin. During the modification of the second-stage APMP with laccase, the contents of aliphatic OH (A-OH)、the contents of COOH and total phenolic OH (T-OH) all decreased. The contents of the condensed phenolic OH (C-OH)、syringyl phenolic (S-OH)、guaiacyl and dementhylated OH (G-OH) and p-hydroxyl-phenyl OH (p-OH) all decreased in the residual lignin.During modification of the first-stage APMP with LMS process, the content of the aliphatic OH (A-OH)、the contents of COOH and the total phenolic OH (T-OH) all decreased. The contents of the condensed phenolic OH (C-OH)、syringyl phenolic (S-OH)、guaiacyl and the dementhylated OH (G-OH) and p-hydroxyl-phenyl OH (p-OH) all decreased in the residual lignin. During he modification of the second-stage APMP with LMS, the content of aliphatic OH (A-OH) increased, the contents of COOH and total phenolic OH (T-OH) both decreased. The contents of the condensed phenolic OH (C-OH)、syringyl phenolic (S-OH)、guaiacyl and dementhylated OH (G-OH) and p-hydroxyl-phenyl OH (p-OH) all decreased in residual lignin.更多还原