【作者】 刘艳兰；

【导师】 陈克复；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2011， 博士

【摘要】 目前,在不使用O₃作为漂白剂的前提下,非木材纤维的全无氯漂白浆白度提高仍然有限。Na₂SiO₃用于过氧化氢漂白,造成的严重缺点是在漂白设备和碱回收设备中产生坚硬的硅垢沉积物,致使设备清洗困难,劳动强度大,还因漂后浆中含有杂质,影响纸浆质量,从而造成纸张强度下降同时废水处理效率降低等。氢氧化钠用于纸浆的过氧化氢漂白,使废水的COD含量高。针对以上的几个问题,本论文对非木材纤维的全无氯漂白技术进行了强化研究,特别是对当前过氧化氢漂白存在的问题进行改进,开发过氧化氢漂白过程中的无硅稳定技术和优化过氧化氢漂白助剂的使用,及研制高白度的麦草和蔗渣全无氯漂白浆,为推进麦草和蔗渣浆TCF漂白技术及漂白系统中“废水零排放”技术的发展提供理论和技术支持。通过上述研究得出以下主要结论:过氧化氢对麦草浆的氧脱木素具有较好的强化效果。过氧化氢的加入使得纸浆残余木素含量降低而粘度损失减小,提高了麦草浆氧脱木素的选择性和脱木素能力,并显著增加氧脱木素后的纸浆白度。麦草浆OQP全无氯漂白对比研究得出,过氧化氢强化氧脱木素能够提高纸浆的后续可漂性能并提高全无氯漂白浆的白度稳定性,而纸浆的物理强度略有降低。非硅稳定剂（PP-1+PP-2）代替硅酸钠作为麦草浆的过氧化氢漂白稳定剂是可行的,在低用量下其漂白效果可与硅酸钠相当。采用二次补碱的后程活化方法可以提高麦草漂后浆的白度,减少过氧化氢的消耗量,而对纸浆的粘度影响不大。在O_p段2.0%的用碱量下,蔗渣浆采用单段过氧化氢强化氧脱木素即可达到良好的脱木素效果。非硅漂白稳定剂（PP-1+PP-2）代替硅酸钠用于压力过氧化氢漂白,在低用量下可达到与3.0%硅酸钠相近的漂后浆白度。蔗渣浆O_pQPo漂后浆的白度达到85.0%ISO。蔗渣浆O_pQPo漂白废水从根本上消除了AOX的产生,产生较低的污染负荷。与使用硅酸钠的漂后浆相比,非硅稳定剂（PP-1+PP-2）漂后浆的抗张指数和耐破指数均显著提高,而撕裂指数略微减小。这说明非硅稳定剂的使用总体上提高了漂后浆的强度。（PP-1+PP-2）作为稳定剂的蔗渣漂后浆的纤维形态和长度分布与Na₂SiO₃作为稳定剂的漂后浆相似。（PP-1+PP-2）漂后的蔗渣浆与Na₂SiO₃的漂后浆相比,表面电荷和羧基含量较高,而Z电位较低。红外光谱分析表明（PP-1+PP-2）明显提高纤维素的结晶区,从而提高纸浆的抗张强度。（PP-1+PP-2）的H₂O₂漂后浆与常规硅酸钠的漂后浆相比,木素的特征吸收峰总体要稍低些,这说明非硅稳定剂对蔗渣浆的脱木素效果要好一些。麦草浆经湿法除尘预处理后,用soda-AQ法进行蒸煮,制得低卡伯值,高粘度的纸浆。低卡伯值麦草浆经氧脱木素（O）和螯合预处理（Q）后,进行两段常压过氧化氢（PP）漂白,漂后浆的最高白度为85.7%ISO,粘度为775mL.g^-1,总的H₂O₂实际消耗量为1.55%。为了满足北美浆纸行业对麦草全无氯漂白浆高白度的要求,将经氧脱木素和螯合预处理后的纸浆进行两段压力过氧化氢漂白（PoPo）的研究,漂后浆的最高白度为90.1%ISO,粘度为479mL.g^-1,总的H₂O₂实际消耗量为6.31%,同时漂后浆的强度性能和纤维形态均较好。压力过氧化氢漂白与常压过氧化氢漂白比较,提高了漂后浆的白度。红外光谱分析表明,麦草浆氧脱木素过程中木素苯丙烷大分子结构的裂解,产生更多的羟基,主要是醚键断裂后生成的酚羟基。螯合段及H₂O₂漂段减少了木素结构中羰基、共轭羰基的生成。Mg（OH）₂作为碱源应用于高卡伯值,高金属离子含量的麦草浆过氧化氢漂白,漂后浆的粘度和得率随Mg（OH）₂取代量的增加而显著提高,H₂O₂的消耗量则随Mg（OH）₂取代量的增加而显著减少。Mg（OH）₂对高Kappa值,高金属离子含量的纸浆过氧化氢漂白效果好于低Kappa值,低金属离子含量的纸浆。Mg（OH）₂部分取代的过氧化氢漂后浆其抗张指数,耐破指数和撕裂指数均高于NaOH漂后浆,而游离度低于NaOH漂后浆。用Mg（OH）₂部分取代NaOH可以显著降低废水中的有机物含量。与NaOH单独作为碱源比较,24%Mg（OH）₂取代量的COD降低了22%。较低的COD有助于减少废水处理的费用。更多还原

【Abstract】 At present, the brightness of non-wood fibers TCF （Total Chlorite Free） bleached pulp was limited. Silicate was a widely used peroxide bleaching stabilizing agent in the pulp and paper industry. Though efficient stabilizer, silicate caused problems in papermaking by contributing to silicate deposit formation, decreased retention and sheet strength, increased anionicity leading to higher consumption of wet end chemicals, and at times scaling in the system. Peroxide bleaching required NaOH as the alkaline source, which caused an increase of the effluent COD. To solve these problems above, this paper studied the strengthen TCF bleaching technology of wheat straw pulp and bagasse pulp, application non-silicate stabilizer into peroxide bleaching, bleached the wheat straw and bagasse TCF pulp to high brightness. The aim of this study was to offer technological and theoretical support for TCF bleaching technology of non-wood fibers in medium consistency pulp bleaching system.Hydrogen peroxide was applied to strengthen the oxygen delignification of wheat straw pulp and the influencing factors were studied. We also investigated the TCF bleaching of wheat straw pulp using an OpQP sequence. The results showed that adding hydrogen peroxide into pulp had a notable effect on oxygen bleaching process. The efficiency and selectivity of oxygen delignification were improved. The OpQP bleaching indicated that the pulp reinforced with H₂O₂ could improve the bleaching efficiency and stability,but reduced slightly the strength of paper .The feasibility of non-silicate stabilizers PP-1, PP-2 applied into wheat straw pulp hydrogen peroxide bleaching was investigated and the optimization of the bleaching chemicals was carried out. The results showed that the substitution of sodium silicate with PP-1,PP-2 as the stabilizer in hydrogen peroxide bleaching for wheat straw pulp was technically feasible. PP-1 contained the scale inhibiton composition, so there was no fouling phenomenon as it caused by sodium silicate.The TCF bleaching of bagasse pulp was carried out, and the possibility of non-silicate stabilizer in hydrogen peroxide bleaching was investigated. The results indicated that non-silicate stabilizers PP-1, PP-2 in place of sodium silicate as the stabilizers in pressured hydrogen peroxide bleaching was technically feasible. The brightness of bagasse pulp with OpQPo bleaching can be achieved to 85%ISO. The pollutant loads of OpQPo sequence were much lower. The fiber morphology, physical strength properties and the charge characteristcs between the （PP-1+PP-2） process and Na₂SiO₃ process were compared. The fiber morphology and length distribution of （PP-1+PP-2） process was silimar to those of Na₂SiO₃ process. The tensile index and tearing index, as well the charge characteristcs were higher than those of Na₂SiO₃ process. The FTIR spectra indicated that （PP-1+PP-2） could increase the crystal area of fiber, so increased the tensile index. And the absorbtion strength of lignin was higher than Na₂SiO₃ bleached pulp, so the （PP-1+PP-2） had stronger delignification.Low kappa number of wheat straw oxygen delignification chelated （OQ） pulp, bleached with two conventional hydrogen peroxide bleaching（PP）, the highest brightness was achieved to 85.7%ISO, viscosity was 775 mL.g^-1, and total H₂O₂ consumption was 1.55%. To meet the required brightness of North American Pulp and Papermaking Industry, the wheat straw OQ pulp bleached with two pressurized hygrogen peroxide bleaching stage （PoPo）. The highest brightness was achieved to 90.1%ISO, viscosity was 479mL.g^-1, and total H₂O₂ consumption was 6.31%. And the strength propersities and fiber morphology was favorable. Pressurized hydrogen peroxide bleaching method increased the bleached pulp brightness. FTIR spectra indicated that wheat straw pulp after oxygen delignification, the lignin cleavaged, produced more hydroxy. And the chelation and hydrogen peroxide bleaching stage decreased the carbonyl of lignin.Mg（OH）₂ substitution of NaOH as the alkaline source in the peroxide bleaching of wheat straw pulp was investigated. The results showed that for the high kappa number, high metal ions of wheat straw pulp, under the same conditions, the bleached pulp brightness, viscosity and yield increased obviously with the increase of substitution degree of Mg（OH）₂, and the residual hydrogen peroxide charge decreased obviously. The bleached pulp of Mg（OH）₂ peoxide bleaching process had higher tensile intex, bursting index, and teraing index, but lower freeness. And Mg（OH）₂ can reduce the COD of effluents, 25% of Mg（OH）₂ substitution of NaOH decreased 22% of the effluent COD.更多还原