【作者】 杨桂花；

【导师】 陈克复；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2009， 博士

【摘要】 本论文以速生杨为纤维原料,对速生杨树干和枝桠材进行了纤维形态观察和化学成分分析,并进行了比较。研究探讨了不同种木聚糖酶在速生杨酶促磨浆、酶促打浆、酶法改性和辅助漂白等制浆过程中的作用效果,优化了酶处理工艺条件,并对经过和未经过酶处理的纸浆纤维形貌、木素含量和结构的变化进行了分析。实验结果显示:不同品种速生杨树干材的纤维长度、纤维粗度和长宽比均好于枝桠材。树干材的综纤维素含量均高于枝桠材,树干材的灰分、1% NaOH抽出物、苯醇抽出物和酸不溶木素均低于枝桠材。速生杨枝桠材的纤维特性指标符合制浆条件的要求,可作为造纸原料来开发利用。在意大利黑杨枝桠材P-RC APMP磨浆过程中,二段磨浆前进行木聚糖酶预处理可以降低磨浆能耗3%~8%,降低后续打浆能耗5%~9%。酶预处理纸浆的白度提高1.0%ISO~2.3%ISO,纸浆的物理性能指标略有变化。三段磨浆前进行酶预处理可以降低磨浆能耗4%~8% ,降低后续打浆能耗5%~13% ,酶处理纸浆的白度提高0.9%ISO~1.2%ISO,纸浆物理强度指标略有提高。三段磨浆前酶预处理的酶促磨浆效果好于二段磨浆前酶预处理;木聚糖酶AU-PE89的酶处理效果好于木聚糖酶51024;木聚糖酶AU-PE89最佳用量为20IU·g-1和30IU·g-1。在混合速生杨P-RC APMP磨浆过程中,三段磨浆前进行木聚糖酶AU-PE89预处理可以降低磨浆能耗6%~10%,降低后续打浆能耗4%~8%。酶预处理纸浆的白度提高1.7%ISO ~1.9%ISO,裂断长提高2%~18%,撕裂指数提高8%~11%,耐破度提高3%~27%,耐折度提高50%。木聚糖酶AU-PE89较适宜的用量为20IU·g-1和30IU·g-1。在速生杨APMP浆和P-RC APMP浆的打浆过程中,木聚糖酶51024预处理APMP浆的打浆能耗下降10%~18%,纸浆白度提高2.2%ISO,裂断长提高10%,撕裂指数提高10%,耐破指数提高21%,耐折度提高50%。酶预处理P-RC APMP浆的打浆能耗降低10%~17%,白度提高1.9%ISO,裂断长提高9%,耐破指数提高12%,耐折度提高75%。在意大利黑杨枝桠材P-RC APMP浆的打浆过程中,木聚糖酶51024预处理明显改善纸浆的打浆性能,打浆能耗降低22%~40%。酶处理纸浆的白度提高1.7%ISO,裂断长提高6%,撕裂指数提高7%,耐破指数提高4%,耐折度提高67%,返黄值降低。用木聚糖酶AU-PE89对速生杨APMP浆进行预处理可明显改善纸浆的滤水性,经过和未经过打浆的纸浆打浆度分别降低3.0°SR~12.0°SR和0.5°SR~6°SR,酶处理纸浆的撕裂指数提高3%~16%,返黄值降低4%~15%,纸浆白度、裂断长和耐破指数略有变化。高用量下酶处理效果较好。酶处理纸浆的戊聚糖含量降低1.64%,纤维素含量和Klason木质素含量相对提高。木聚糖酶AU-PE89可以改善速生杨APMP浆的滤水性能和留着性能,助留助滤作用明显。木聚糖酶AU-PE89最佳助滤条件为:pH值7.0,酶用量1.5IU·g-1,温度45℃,时间30min和浆浓0.5%。此处理条件下,速生杨APMP浆的打浆度下降4.5oSR,动态滤水时间t3缩短2.8s,Zeta电位(负值)降低0.6mv,细小组分留着率提高61.3%,AKD施胶效果略有上升。木聚糖酶AU-PE89辅助漂白效果好于AU系列木聚糖酶。对于速生杨KP浆HP和DP短程序漂白,木聚糖酶AU-PE89预处理可以提高漂白浆的白度1.1%ISO~3.1%ISO,当混合速生杨KP浆漂白至相近白度时,节省漂白药剂用量14%~33%。对于速生杨NaOH-AQ浆,增加木聚糖酶处理段的(OO)DXP和(OO)XDED两种ECF漂白程序可使速生杨NaOH-AQ浆漂白至85%ISO以上的白度,其中(OO)XDED漂白程序可使纸浆白度达到88.8%ISO。TCF漂白程序(OO)QXP可获得80%ISO以上的白度。纤维质量分析仪分析结果表明,经过木聚糖酶处理的速生杨APMP浆和P-RC APMP浆的纤维长度增加,纤维宽度和细小纤维数量减小,纤维扭结指数增大,这有利于提高纸浆物理强度。在扫描电镜下观察,未经过木聚糖酶处理的纸浆纤维比较挺硬,细小纤维较少,纤维分丝帚化程度较低。经过酶处理的纸浆纤维较柔软,纤维表面有较多凹陷,出现分丝帚化现象,木聚糖酶能够使纤维细胞壁变得疏松,使纤维柔软松散,易于磨浆和打浆。原子力显微镜观察表明,木聚糖酶处理的速生杨纸浆纤维表面微细纤维纹理清晰,纤维表面较粗糙,凸凹程度增加,纤维表面部分木聚糖被木聚糖酶降解,更多微细纤维裸露,纤维更容易产生分丝帚化,这是木聚糖酶处理能降低磨浆和打浆能耗,提高纸浆白度和物理强度的原因。X射线衍射表明,酶处理使纤维素结晶度有所提高。红外光谱显示,经过木聚糖酶处理的纸浆羟基增加,木聚糖含量有所降低,部分木素溶出,纸浆易于润胀,水化程度提高,纸浆白度增加。更多还原

【Abstract】 The fiber morphology observation and chemical composition analysis of both fast-growing poplar trunk wood and brushwood were investigated in this thesis as well as the fibers characteristics comparison of these two kinds of wood. Different xylanases were used and the effectiveness was tested and studied during the fast-growing poplar pulping process including enzyme-boosting refining, enzyme-boosting beating, enzymatic modification and enzymatic assistant bleaching. This thesis optimized the treatment conditions, and analyzed the changes of fiber morphology, chemical structure and lignin molecular weight during the xylanase treatment as well.The results showed that the fiber length and fiber coarseness of poplar trunk wood are better than that of branch wood as well as the ratio of fiber length to width (L/W). The holocellulose content of poplar trunk wood is higher than that of brushwood, however, the ash contenct, 1% NaOH extracted substances content, benzene-alcohol extracted substances extent and acid-insoluble lignin content are lower than that of brushwood. The fiber characteristics of brushwood have reached the pulping requirement, which indicates that this fast-growing poplar brushwood can be developed as material for pulp and paper making industry.Xylanase pretreatment before the second refining stage during Italian black poplar branch wood P-RC APMP process can reduce the refining energy consumption by 3 % ~ 8 % as well as 5%~9% for following beating energy consumption. In addition, the resulting pulp brightness can be improved by 1.0%ISO~2.3%ISO with minor change of pulp strength properties. Xylanase pretreatment before the third refining stage can reduce the refining energy consumption by 4 % ~ 8 % as well as 5%~13% for following beating energy consumption. The resulting pulp brightness is improved by 1.0%ISO~2.3%ISO with minor improvement of pulp strength properties. The application of xylanase before the second refining stage is better than that before the third refining stage. Among different xylanases used in this study, the AU-PE89 is best, and the optimal dosage of AU-PE89 is 20IU·g-1 and 30IU·g-1 respectively.The AU-PE89 xylanase pretreatment before the third refining stage during the mixed fast-growing poplar P-RC APMP process can reduce the refining energy consumption by 6%~10% and lower the following beating energy consumption by 4%~8% with the improvement of 1.7%ISO~1.9%ISO resulting brightness, 2%~18% breaking length, 8%~11% tear index, 3%~27% burst index and 50% folding endurance. The optimal dosage of AU-PE89 is 20IU·g-1 and 30IU·g-1.During the beating of mixed fast-growing poplar APMP and P-RC APMP, the 51024 xylanase pretreatment for APMP pulp can reduce 10%~18% beating energy consumption with the improvement of resulting brightness by 2.2% ISO, breaking length by 10%, tear index by 10%, burst index by 21% and folding endurance by 50%. The xylanase pretreatment for P-RC APMP pulp can decrease 10%~17% beating energy consumption with the improvement of 1.9%ISO brightness, 9% breaking length, 12% bursting index and 75% folding endurance.During the beating of Italian black poplar branch wood P-RC APMP pulp, the 51024 xylanase pretreatment can obviously improve the pulp beatability, and the beating energy consumption can be reduced by 22%~40% as well. The brightness, breaking length, tear index, burst index and folding endurance of pretreated pulp can be improved by 1.7%ISO, 6%, 7%, 4%, and 67% respectively. In addition, the treated pulp has lower PC number.The AU-PE89 xylanase pretreatment for fast-growing poplar APMP pulp can obviously improve the drainage capability. The beating degree of pretreated pulp decreased by 3.0°SR~12.0°SR and 0.5°SR~6°SR respectively for the beated pulp and non-beated pulp. The tear index of pretreated pulp is improved by 3%~16%, and the PC number decreased by 4%~15% with minor change of brightness, breaking length and burst index. Compared with the unpretreated pulp, the pretreated pulp has 1.64% lower pentosan content, and higher reversely cellulose content and Klason lignin content.The xylanase AU-PE89 treatment for fast-growing poplar APMP pulp can obviously improve the drainage capability and retention capability. The optimal treatment conditions for improving the pulp drainage are pH 7.0, AU-PE89 1.5IU·g-1, 45℃, 30min and 0.5% pulp consistency. Based on the optimal treatment conditions, the beating degree of treated pulp decreased by 4.5oSR, the dynamic drainage time reduced by 2.8s, Zeta potential (minus) reduced by 0.6mV, the retention of fines increased by 61.3%, the effect of AKD sizing promoted a little, and the breaking length, bursting index, and the tearing index increased by 6.2%, 9.5%, and 4.0% respectively.The bleach boosting effects of AU-PE89 xylanases are better than that of AU xylanases. For DP and HP bleaching sequences,the AU-PE89 xylanase pretreated pulp can has 1.1%ISO~3.1%ISO higher brightness than that of unpretreated pulp. At the condition of reaching similar brightness, the AU-PE89 xylanase pretreated pulp can can save 14%~33% bleaching chemicals.For fast-growing poplar Kraft pulp, the AU-PE89 can give better assistant bleaching effectiveness. The resulting pulp brightness can be improved by 1.8%ISO~2.7%ISO at the optimal treatment condition of pH 7.0. For fast-growing poplar NaOH-AQ pulp, both (OO)DXP and (OO)XDED, xylanase-including bleaching sequences, can make the resulting pulp brightness higher than 85% ISO. Especially the (OO)XDED bleaching sequence can give the resulting pulp 88.8% ISO brightness. For the TCF bleaching, the (OO)QXP can give the pulp higher than 80%ISO brightness.The fiber quality analysis showed that, compared with the untreated pulp, both the xylanase-treated poplar APMP and P-RC APMP have longer fiber length, higher fiber kink index, smaller fiber width, and lower fines content, which benefits the improvement of pulp strength properties.The SEM observation indicated that the xylanase-untreated pulp has stiffer fiber, less fines and lower fibrillation extent. In addition, the xylanase-treated fibers are softer and has higher fibrillation extent compared with the untreated fiber, and there are many hollows on the fiber surface. The xylanase treatment looses the fiber cell wall and softens the fiber so as to be easy for refining and beating.AFM observation showed that xylanase treatment made the microfibril texture on fiber surface more clearly, the surface of fiber became more coarse, and the smoothness of fiber surface decreased. Part of xylan on fiber surface was degraded by xylanase during the treatment and more microfibrils were exposed. The fibers treated by xylanase are easier to be splitted and broomed, which was responsible for the decrease of refining/beating energy consumption and the increase of pulp brightness and physical strength.XRD analysis indicated that degree of crystallinity of fiber increased after the xylanase treatment. In addition, the IR spectrum showed that the hydroxyl group content increased, however, the xylan content decreased. Part of lignin dissolved out from the fibers so that the pulp brightness increased and the pulp treated by xylanase is easier to be swollen.更多还原