【作者】 徐清华；

【导师】 石淑兰； 秦梦华；

【作者基本信息】 天津科技大学 ， 制浆造纸工程， 2005， 博士

【摘要】 废纸的回收利用是解决造纸工业面临的原料短缺、能源紧张和污染严重等三大问题的有效途径。脱墨是废纸回用技术的关键。与常规的化学脱墨相比,酶法脱墨具有很多优点。目前废纸的纤维素酶和半纤维素酶法脱墨已实现工业化。探索其他可用于废纸脱墨的酶对于酶法脱墨的发展具有很重要的意义。木素降解酶可以通过氧化降解纸浆表面的木素来达到脱除油墨的目的,这对于主要由机械浆组成的废新闻纸具有很大的吸引力。漆酶（EC1.10.3.2）是木素降解酶的一种,在某些具有传递电子能力的介体和氧气的存在下,能够使木素发生氧化降解,具有很广阔的应用前景。 采用快速、直观、准确的方法对废纸浆进行质量评价,对于控制和优化脱墨工艺,保证再生纤维抄成的纸满足质量要求非常重要。系统地研究脱墨浆质量评价方法具有很重要的意义。 本论文首先采用各种方法对ONP及MOW废纸的脱墨效果进行评价,研究不同的制样方法对脱墨效果及脱墨效率评价的影响。不同的抄片方法对脱墨浆质量评价的影响是很大的。对于ONP化学脱墨浆和酶法脱墨浆,采用标准抄片器,用自来水,不调pH和添加PAM抄片时,所得浆片的两面差很小,油墨粒子的留着率最高。而对于MOW化学脱墨浆和MOW酶法脱墨浆,采用布氏漏斗,用去离子水,添加PAM和Al₂（SO₄）₃抄片时,所得浆片的两面差很小,白度最低,尘埃度及残余油墨浓度最高,油墨粒子的留着率最高。将白度、残余油墨浓度与图像分析法相结合,可以全面而准确地对废纸脱墨效果进行评价,从而优化脱墨工艺。计算各种脱墨过程的实际脱墨效率和理论脱墨效率,发现实际脱墨效率总是小于理论脱墨效率。说明脱墨工艺,脱墨条件还有进一步优化的空间。 利用漆酶/介体可以对8#美废进行脱墨。废新闻纸漆酶/介体系统脱墨的最佳工艺条件为:漆酶用量10LAMU/g,介体（VIO）用量0.5%,碎浆时间30min,保温时间15min,通氧气。在此条件下进行脱墨,所得脱墨浆白度与对照浆相比有所降低,但可漂性提高。H₂O₂漂白后白度达到52.4%ISO,与对照浆相比提高4.2%ISO。此时裂断长为2.16km,撕裂指数为7.01mN·m²·g^-1,与对照浆相比分别提高了20%和13%。漆酶脱墨浆得率明显高于对照浆。其浮选过程中的选择性亦高于对照浆。利用漆酶/介体对国产废新闻纸进行脱墨,所得结果与8#美废类似,也可以达到较好的脱墨效果。 纤维素酶与漆酶具有协同脱墨作用。其最佳工艺条件为:先加入纤维素酶0.2ECU/g脱墨25min,然后加入漆酶3LAMU/g,介体0.5%,保温30min,更多还原

【Abstract】 The Recycling of wastepaper is an effective way to resolve those problems that pulp and paper industry now is facing, such as shortage of raw materials, lacking of energy, pollution, et al. Deinking is the key of recycling. Contrary to conventional chemical deinking, enzymatic deinking has many priorities. Now deinking with cellulase and hemicellulase has been industrialized. It is significant to search other enzymes that could be used in deinking.Ligninases that catalyze the removal of surface lignin are promising for deinking of old newsprint that contains lignin-rich mechanical pulp. Ligninases include three enzymes-LiP, MnP and laccase. Laccase（EC1.10.3.2）is a polyphenol oxidase, and it can degrade the lignin when used in the presence of a chemical mediator and oxygen.It is important to evaluate the quality of deinking pulp quickly and correctly to control and optimize deinking technology, and to ensure paper made from the secondary fiber could meet the needs. So it is significant to study methods of qulity evaluation of deinked pulps.Different specimen preparation methods were used to evaluate deinked pulp quality and deinking efficiency. To ONP chemically and enzyme deinked pulp, wire-blotter difference of specimen prepared using standard methods, tap water, no adjustment of pH, adding PAM was the least and retention of ink particles was the highest. To MOW chemical and enzyme deinked pulp, wire-blotter difference of specimen prepared using buchner funnel procedure, distilled water, adding PAM and Al₂（SO₄）₃ was the least and retention of ink particles was the highest. Quality of deinked pulps could be evaluated quickly and correctly to combining brightness with image analysis and ERIC. Calculating practical and theoretical deinking efficiency during deinking process, results demonstrated that practical deinking efficiency was always smaller than theoretical deinking efficiency which clarified that deinking technology could be further optimized.Deinking technology of ONP with Laccase mediator system（LMS） was studied. Results showed that it was practicable to deink ONP with LMS. The optimum pulping conditions were: laccase charge 10 LAMU/g, mediator （violuric acid） charge 0.5%, time of pulping 30 min, and keeping the pulp at the optimum temperature for 15 min. yield of LMS deinked pulp was higher than the control pulp. Its flotation selectivity was also higher.Deinking technology of ONP by cellulase/hemicellulase combined with LMSwas studied. Results showed that cellulase/ hemicellulase combined with LMS could deink ONP synergistically. The optimum conditions of LMS /cellulase deinking were: first deinking with 0.2 ECU/g cellulase for 25 min, and then keeping temperature at 55 "C with 3 LAMU/g laccase and 0.5% mediator for 30 min. The optimum conditions of LMS /hemicellulase deinking were: first deinking with 0.5 AXU/g cellulase for 25 min, and then keeping temperature at 55 °C with 3 LAMU/g laccase and 0.5% mediator for 30 min. Yield and flotation selectivity of LMS deinked pulp were higher than those of the control.Fiber morphology of deinked pulps were studied by ESCA, IR, SEM. Fiber average length and coarseness, specific surface area and specific volume were determined. ESCA analysis showed that O/C of LMS deinked pulp was higher than that of the control pulp;surface lignin content decreased after LMS treatment. IR analysis showed that some lignin was dissolved during LMS treatment. Fiber average length and coarseness changed little even though a large dosage of laccase was used, which declared that laccase action mainly occurred at the surface of fiber, and could not touch inner of the fiber. Specific surface area and specific volume analysis of LMS deinked pulp were higher than those of control pulp. SEM Results showed that defiberaion took place at the fiber surface.Dioxane lignin of deinked pulp was extracted and its structure was analyzed by elemental analysis, functional groups determination, GPC, IR, ’H-NMR and 2D-NMR. Comparing with lignin from control pulp, phenolic hydroxy and methoxyl content of lignin from LMS deinked pulp decreased, while content of carboxyl and carbonyl groups increased. IR results showed that lignin was degraded during LMS treatment. Content of methoxyl, phenolic hydroxy, hydroxy of lignin were calculated through ’H-NMR. They all decreased after laccase treatment. 2D-NMR results showed that guaiacyl unit was oxidized by LMS. Stilbene, dibenzene methane and 5-5’type sub-structure in lignin were stable to LMS treatment, while P -O-4 and P - P type sub-structure were degraded.Combining fiber morphology with lignin structure analysis, probable mechanism of LMS deinking could be inferred. First, mediator was oxidized to mediator complex by laccase with the presence of oxygen. This mediator complex was very small, so it could osmose into the fiber and oxidativly degraded lignin. The bond between ink and fiber became loose. Ink could be peeled off the fiber at the aid of shear force.更多还原