漆酶降解木质素及其抗氧化性能的研究

发布时间：2018-05-12 15:14

  本文选题：漆酶 + 降解　； 参考：《广西大学》2017年硕士论文

【摘要】：随着人类社会的快速发展,世界能源的消耗量也日益加剧,三大能源(煤、石油、天然气)毕竟来源有限,早已不能满足人类社会的需要。另一方面,人工合成物质的潜在危害性也加剧了科学家向天然可再生产物领域的研究进程。木质素是自然界中含量仅次于纤维素的一类可再生有机物,它来源广泛,化学结构复杂,具有一定的抗氧化性,但其抗氧化性远远低于人工合成的抗氧化剂。本文通过漆酶降解的方法来提高木质素的抗氧化性,为木质素可作为天然抗氧化剂提供理论支持,增加木质素综合利用的附加价值。主要的研究内容与结果如下:(1)利用漆酶降解碱木质素(AL),并从溶剂pH值、反应温度、反应时间、漆酶添加量等因素,探究对其抗氧化能力的影响,得到最佳降解条件为:pH=5.0、T=25℃、t=6h、V酶=1.2mL·g-1(AL)。(2)采用DPPH法表征碱木质素的抗氧化能力,实验结果表明:降解碱木质素(DAL)的抗氧化能力(IC50=56.75μg·mL~(-1))明显强于AL(IC50=396.2μg·mL~(-1));FTIR、SEM、粒径、GPC等分析手段表明:降解之后,碱木质素的主要官能团没有改变,分子变小和更松散,分子量也变小;在主要官能团含量测定实验中发现:DAL的酚羟基含量(1.39 mmol·g-1)明显高于 AL(0.512mmol·g-1),甲氧基含量(1.06 mmol·g-1)低于 AL(4.06 mmol·g-1)。降解之后,酚羟基含量的剧增和降解产物分子形貌的改变,使得DAL的抗氧化能力强于AL。(3)利用漆酶降解水解木质素(HL),并从溶剂pH值、反应温度、反应时间、漆酶添加量等因素,探究对其抗氧化能力的影响,得到最佳降解条件为:pH=5.6、T=35 ℃、t=4h、V酶=1.0mL·g-1(HL)。(4)采用DPPH法表征水解木质素的抗氧化能力,实验结果表明:降解水解木质素(DHL)的抗氧化能力(IC50=28.78 μg·mL~(-1))强于HL(IC50=31.25μg·mL~(-1));FTIR、SEM、粒径、GPC等分析手段表明:降解之后,水解木质素的主要官能团没有改变,分子变小和更松散,分子量也变小;在主要官能团含量测定实验中发现:DHL的酚羟基含量(1.96 mmol·g-1)高于 HL(1.81mmol·g-1),甲氧基含量(7.53mmol·g-1)也高于HL(4.22 mmol·g-1)。降解之后,甲氧基含量的大幅度提升,即使是在酚羟基小幅度提升的前提下,再加上分子形貌的改变,使得DHL的抗氧化能力还是强于HL。(5)酚羟基是决定抗氧化能力最主要的官能团,其含量越高,抗氧化能力越强;甲氧基能促进抗氧化能力的提高,其含量越高,效果越明显。
[Abstract]:With the rapid development of human society, the consumption of energy in the world is increasing day by day. After all, the three major energy sources (coal, oil, natural gas) are limited, and can not meet the needs of human society. On the other hand, the potential harmfulness of synthetic substances also intensifies the research progress in the field of natural renewable products. Lignin is a kind of renewable organic substance in nature, which is second only to cellulose in content. It has a wide range of sources, complex chemical structure and certain antioxidant properties, but its antioxidant activity is far lower than that of synthetic antioxidants. In this paper, the method of laccase degradation is used to improve the antioxidant ability of lignin, which can provide theoretical support for lignin as a natural antioxidant and increase the added value of comprehensive utilization of lignin. The main research contents and results are as follows: (1) using laccase to degrade alkali-lignin (ALP) and to explore the effects of solvent pH value, reaction temperature, reaction time, laccase addition and other factors on its antioxidant ability. The optimum degradation conditions were obtained as follows: ph: 5. 0 ~ (5. 0) T ~ (2 +) = 1. 2 mL / g ~ (-1) ALN. 2) Antioxidant ability of alkali lignin was characterized by DPPH method. The results showed that the antioxidant capacity of alkaline lignin was 56.75 渭 g / mL ~ (-1), which was obviously better than that of AL(IC50=396.2 渭 g / mL ~ (-1) ~ (-1) DPPH. The results showed that: after degradation, the antioxidation ability of alkaline lignin was 56.75 渭 g / mL ~ (-1), which was obviously better than that of AL(IC50=396.2 渭 g / mL ~ (-1) / L ~ (-1). The main functional groups of alkali lignin were not changed, and the molecular weight became smaller and looser, and the content of phenolic hydroxyl group was 1.39 mmol / g ~ (-1), and the content of methoxy group was 1.06 mmol / g ~ (-1) lower than that of AL(4.06 mmol g ~ (-1). After degradation, the content of phenolic hydroxyl groups and the molecular morphology of degradation products increased dramatically, which made the antioxidant ability of DAL stronger than that of AL.3. The hydrolyzed lignin HLN was degraded by laccase, and the factors such as pH value of solvent, reaction temperature, reaction time, laccase addition, etc. The optimum degradation conditions were as follows: 1. 0ml / g-1hmg-1hl-1 HL-4 at 35 鈩，

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