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Biobleaching of kraft pulp with recombinant manganese peroxidase.

机译：用重组锰过氧化物酶对牛皮纸浆进行生物漂白。

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摘要

Recombinant manganese peroxidase (rMnP) produced from the yeast Pichia pastoris in high cell density, fed-batch fermentations was tested for its ability to degrade lignin in kraft pulps. Softwood kraft pulp, hardwood kraft pulp and oxygen delignified hardwood kraft pulp were used to investigate the enzyme effectiveness in treating pulps with different amount of initial lignin or lignin structure. In all cases, a significant reduction in kappa number was observed by including rMnP at a dosage of 30U/g pulp. No difference was observed between softwood kraft pulp and hardwood kraft pulp in the delignification rates. High lignin content (lightly cooked) kraft pulps showed similar deligninfication rates as the normal kraft pulps. However, the highly delignified pulps, whether it is oxygen delignified or overcooked to kappa numbers below 10, are less susceptible to delignification by rMnP compared to the normal pulps. Repeated rMnp treatments combined with alkaline extraction gave more extensive delignification. It reduced kappa number by 61%, which is about three times of a single rMnP treatment. A sequential enzymatic beaching with xylanase and rMnp provided higher kappa number reduction compared to the individual enzymatic treatment and the simultaneous treatment with both enzymes.; The effects of Manganese ion, hydrogen peroxide on the oxidation of 2,6-dimethoxyphenol (DMP) were investigated to establish the optimal application of rMnP oxidative system. Manganese ion showed a positive effect on the reaction rate, which was dependent on the concentration of hydrogen peroxide. High concentration of hydrogen peroxide caused partial inactivation of enzyme and as a result reducing the positive effect of manganese concentration on the oxidation rate. Concentrations of 0.8 mM manganese ion and 0.05 mM hydrogen peroxide were found to maximize the catalytic properties of rMnP for the oxidation of DMP.; The effects of hydrogen peroxide, Mn2+ concentration, organic acid chelating agent, surfactant, pH, enzyme dosage and pulp concentration on the lignin degradation during biobleaching of hardwood kraft pulp with rMnP were evaluated. 10mM H2O2 supplied semi-continuously (pulse concentration 0.1mM) provided the best bleaching results in terms of kappa number reduction and pulp brightness improvement. Higher concentrations of H2O2 caused a significant loss of rMnP activity during bleaching. The optimal Mn2+ concentration for lignin oxidation was in the range of 0.1∼0.2 mM. Organic acids such as malonate and oxalate stimulated lignin degradation, whereas succinate and acetate showed no effect on delignification. The optimal pulp concentration for rMnP biobleaching was below 2%. Higher pulp concentration resulted in less bleaching efficiency by rMnP.; rMnP also were tested for its ability to bleach kraft pulp in total chlorine free (TCF) and elemental chlorine free (ECF) bleaching sequences. For TCF bleaching, the sequence used was O(rMnP)QP where O stands for oxygen delignification, rMnP for the enzymatic treatment, Q for the chelating agent stage and P for the alkaline peroxide stage. The inclusion of the enzymatic treatment significantly improved the final brightness of the hardwood kraft pulp compared to the control pulp. Furthermore, the treatment with rMnP resulted in a significant energy saving during pulp refining with PFI mill with a slight improvement in pulp strength properties such as tensile index and tear index. For ECF bleaching, the sequence used was DED for hardwood kraft pulp and DEDED for softwood kraft pulp, where D stands for chlorine dioxide stage and E for alkaline extraction stage. Three-time repeated rMnP treatments combined with alkaline extraction were applied as pretreatment prior to DED or DEDED bleaching sequences, and the total effective chlorine required to obtain a pulp of 88% ISO brightness was reduced by 41% and 30% for hardwood kraft pulp and softwood kraft pulp respectively, compared to the conventional
机译：测试了巴斯德毕赤酵母在高细胞密度，补料分批发酵中产生的重组锰过氧化物酶（rMnP）降解牛皮纸浆中木质素的能力。使用软木牛皮纸浆，硬木牛皮纸浆和氧脱木质素硬木牛皮纸浆来研究酶处理不同初始木质素或木质素结构量的纸浆的酶效力。在所有情况下，通过以30U / g纸浆的剂量加入rMnP，可观察到kappa值显着降低。软木牛皮纸浆和硬木牛皮纸浆的脱木质素率没有差异。高木质素含量（轻度煮熟）的牛皮纸浆显示出与普通牛皮纸浆相似的去木质素率。然而，与普通纸浆相比，高度脱木素的纸浆，无论是氧气脱木素还是过蒸至低于10的卡伯值，都不太容易被rMnP进行脱木素。重复的rMnp处理与碱萃取相结合，可得到更广泛的脱木素作用。它减少了61％的卡伯值，约为单次rMnP处理的三倍。与单独的酶处理和同时使用两种酶的处理相比，使用木聚糖酶和rMnp的顺序酶促海滩化可提供更高的卡伯值降低。研究了锰离子，过氧化氢对2,6-二甲氧基苯酚（DMP）氧化的影响，建立了rMnP氧化体系的最佳应用。锰离子对反应速率有积极影响，这取决于过氧化氢的浓度。高浓度的过氧化氢导致酶部分失活，结果降低了锰浓度对氧化速率的积极影响。发现浓度为0.8 mM的锰离子和0.05 mM的过氧化氢可最大化rMnP催化DMP氧化的性能。考察了过氧化氢，Mn2 +浓度，有机酸螯合剂，表面活性剂，pH，酶用量和纸浆浓度对木质素牛皮纸浆rMnP漂白过程中木质素降解的影响。就减少卡伯值和提高纸浆白度而言，半连续供应10mM H2O2（脉冲浓度为0.1mM）提供了最佳的漂白效果。在漂白过程中，较高浓度的H2O2导致rMnP活性大大降低。木质素氧化的最佳Mn2 +浓度为0.1〜0.2 mM。有机酸（如丙二酸酯和草酸酯）会刺激木质素降解，而琥珀酸酯和乙酸酯则对脱木素没有影响。 rMnP生物漂白的最佳纸浆浓度低于2％。较高的纸浆浓度导致rMnP的漂白效率降低。还对rMnP进行了以总无氯（TCF）和无元素氯（ECF）漂白顺序漂白牛皮纸浆的能力的测试。对于TCF漂白，使用的顺序为O（rMnP）QP，其中O代表氧去木质素，rMnP代表酶处理，Q代表螯合剂阶段，P代表碱性过氧化物阶段。与对照纸浆相比，酶处理的加入显着改善了硬木牛皮纸浆的最终白度。此外，rMnP处理在PFI磨浆过程中导致了显着的节能，并且在纸浆强度特性（如拉伸指数和撕裂指数）方面略有改善。对于ECF漂白，所用的顺序是硬木牛皮纸浆的DED和软木牛皮纸浆的DEDED，其中D代表二氧化氯阶段，E代表碱萃取阶段。在进行DED或DEDED漂白程序之前，将三次重复的rMnP处理与碱提取相结合用作预处理，获得88％ISO亮度的纸浆所需的总有效氯分别降低了41％和30％（对于硬木牛皮纸浆和软木牛皮纸浆，与常规纸浆相比

著录项

  • 作者

    Xu, Haowen.;

  • 作者单位

    State University of New York College of Environmental Science and Forestry.$bEnvironmental & Resources Engineering.;

  • 授予单位 State University of New York College of Environmental Science and Forestry.$bEnvironmental & Resources Engineering.;
  • 学科 Engineering Chemical.; Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 189 p.
  • 总页数 189
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化工过程（物理过程及物理化学过程）;环境污染及其防治;
  • 关键词

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