杨木镁碱过氧化氢化学机械法制浆及其机理研究

发布时间：2018-01-25 08:13

本文关键词： 氢氧化镁碱性过氧化氢机械浆纸浆性能纤维质量分析　出处：《山东轻工业学院》2010年硕士论文　论文类型：学位论文

【摘要】： 在传统的杨木APMP制浆中,原料的碱性H2O2预处理所需要的碱性条件一般由加入的NaOH提供,NaOH的强碱性容易引起碳水化合物的部分降解,降低了得率,降解产物进入废液增加了预处理流出液中COD的含量,增加了污染负荷,而Mg(OH)2的弱碱性,可以弥补钠碱的上述缺陷,因而采用Mg(OH)2的杨木APMP制浆技术受到关注。本论文主要进行了Mg(OH)2为碱源或部分碱源的杨木APMP制浆及其机理的研究,包括单段预处理和两段预处理制浆工艺及对杨木单段预处理镁碱APMP制浆工艺参数的探讨。同时利用FQA、ESEM、XPS等分析手段对镁碱杨木APMP浆的纤维特性进行了研究。首先,镁碱作为碱源时,杨木单段预处理APMP制浆时较为适宜的化学预处理条件为:H2O2:5.0-6.0%,Mg(OH)2:4.35%,Na2SiO3:4.0%,EDTA:0.5%,液比:4:1,反应温度70-80℃,反应时间90 min。在该工艺条件下,当打浆度为450SR时,可得到白度为67.5-68.4%ISO,不透明度91.1%,光散射系数为47.65 m2·kg-1的浆料,但浆的强度较差,裂断长仅为1.32 km,撕裂指数仅为1.63 mN·m2·g-1。其次,通过对氢氧化镁部分或全部取代氢氧化钠的杨木APMP制浆的研究,发现,随着Mg(OH)2取代NaOH的量的增加,纸张的物理强度和白度下降,但不透明度、松厚度和光散射系数提高。镁碱部分取代单段杨木APMP制浆的较佳工艺条件为:Mg(OH)2取代量为50%,H2O2:5.0%,Na2SiO3:4.0%,EDTA:0.5%,液比:4:1,反应时间80 min;两段杨木APMP制浆的较佳工艺条件为:第一段全用氢氧化钠,第二段Mg(OH)2取代量为50%。在该工艺条件下,可得到白度为71.9%ISO,裂断长为3.76 km,撕裂指数为4.53 mN·m2·g-1,不透明度83.3%,光散射系数为42.52 m2·kg-1的浆料。与此同时,采用Mg(OH)2的杨木APMP制浆可以有效降低废水COD含量。随着氢氧化镁取代量的增加,制浆废液中的COD含量下降,从而更有利于实现清洁生产。在相同OH-用量的情况下,随着氢氧化镁取代量的增加,纸浆中木素、碳水化合物和有机溶剂抽出物溶出率均下降。再次,通过对浆料纤维质量分析和纸浆纤维扫描电镜形貌图的观察,发现,随着Mg(OH)2取代量的增加,所得纸浆纤维的长度加权平均长度逐渐变短,不论是数均细小纤维含量还是长度加权含量,均表现为随着Mg(OH)2取代量的增加逐渐增加。最后,通过对不同镁碱取代的杨木APMP纸浆纤维表面XPS分析,表明,随着氢氧化镁取代量的增加,C1s结合能下降,C1s峰面积增大,O1S峰面积减少,即O/C比减少,说明,镁碱杨木APMP浆纤维表面木素含量增加,碳水化合物含量减少;同时通过对丙酮抽提前后的纸浆纤维的XPS对比分析,丙酮抽提后的O/C比增加,降低了纤维表面木素等疏水性物质的含量。镁碱APMP浆料其强度性能较差的原因主要有以下几点:①镁碱的弱碱性以及Mg2+在纤维表面的吸附,使得纤维的润胀度差,纤维柔韧度下降,从而使磨浆进程中,纤维切断较多,纤维平均长度较短,细小纤维含量较高;②镁碱的弱碱性使得纤维表面木素溶出较少,况且纤维表面的疏水性物质含量增加,阻碍了纤维与纤维之间的联接与结合。
[Abstract]:In the traditional APMP pulping of poplar in alkaline conditions to H2O2 alkaline pretreatment of the raw materials is usually provided by the addition of NaOH, NaOH basic is easy to cause degradation of carbohydrates, reducing the yield rate, degradation products into the waste pretreatment effluent increased the content of COD, increase the pollution load, and Mg (OH) alkaline 2, these can make up the defects of sodium alkali, so using Mg (OH) 2 poplar APMP pulping technology is concerned.
This paper mainly discussed the Mg (OH) 2 as the alkali source or partial alkali source and APMP pulping of poplar and its mechanism, including the single segment pretreatment and two stage pretreatment pulping of poplar and single alkali pretreatment of magnesium APMP pulping process parameters is discussed. At the same time the use of FQA, ESEM, fiber characteristics XPS analysis of magnesium base of Aspen APMP pulp was studied.
First of all, magnesium alkali as the alkali source, poplar single stage pretreatment of APMP pulping is appropriate chemical pretreatment conditions were: H2O2:5.0-6.0%, Mg (OH) 2:4.35%, Na2SiO3:4.0%, EDTA:0.5%, liquid ratio 4:1, reaction temperature 70-80, reaction time 90 min. under these conditions, when the beating degree is 450SR when can get the white degree is 67.5-68.4%ISO, 91.1% opacity, light scattering coefficient is 47.65 m2 / kg-1 slurry, but the poor strength of pulp, the breaking length is 1.32 km, the tear index is only 1.63 mN - M2 - g-1.
Secondly, through the research of magnesium hydroxide, partially or completely replace sodium hydroxide APMP pulping of poplar was found, with Mg (OH) 2 substituted amount of NaOH increased, decreased the physical strength of the paper and whiteness, but the bulk and opacity, light scattering coefficient increased. Magnesium base part used to replace single segment of poplar APMP and the optimum process conditions are as follows: Mg (OH) 2 substituted amount was 50%, H2O2:5.0%, Na2SiO3:4.0%, EDTA:0.5%, liquid ratio 4:1, reaction time 80 min; two poplar APMP pulping the optimum process conditions are as follows: the first section of the whole with sodium hydroxide, second Mg (OH) 2 substituted amount of 50%. in this condition, can get the white degree is 71.9%ISO, the breaking length is 3.76 km, the tear index of 4.53 mN - M2 - g-1, 83.3% opacity, light scattering coefficient is 42.52 m2 / kg-1 slurry. At the same time, using Mg (OH) 2 poplar APMP pulping wastewater can effectively reduce the COD with the substitution amount of magnesium hydroxide content. The increase of COD content in pulping waste liquor decreases, which is more conducive to cleaner production. Under the same OH- dosage, the dissolution rate of lignin, carbohydrates and organic solvent extractives decreased with the increase of magnesium hydroxide substitution.
Again, through the observation on the pulp fiber quality analysis and SEM morphology of pulp fibers found in Mg (OH) 2, with the increase of the amount of substitution, the length weighted average length of the pulp fibers gradually become shorter, regardless of number of small fiber content and length weighted content, were performed with Mg (OH) 2 the increase of the amount of substitution increased.
Finally, through the XPS of poplar APMP pulp fiber surface to replace different magnesium base analysis shows that, with the increasing amount of magnesium hydroxide to replace C1s with C1s, can be decreased, the peak area increased and the peak area of O1S decreased, O/C ratio decreased, shows that the increase of magnesium base of Aspen APMP pulp fiber surface lignin content, carbohydrate content decreased at the same time; based on the comparison between XPS analysis before and after acetone extraction of pulp, acetone extraction after O/C ratio increased, decreased the content of fiber surface lignin and other hydrophobic substances.
The strength of APMP slurry of magnesium alkali poor performance mainly in the following points: 1. Alkaline magnesium alkali and Mg2+ adsorption on the surface of the fiber, so that the differential degree of swelling of fiber, fiber flexibility decreased, so that the grinding process, fiber cut more, the average fiber length is shorter, higher fines content the alkali alkaline magnesium; the fiber surface lignin dissolution and less hydrophobic substances on the surface of the fiber increased, hinder the connection between the fiber and the fiber and binding.

【学位授予单位】：山东轻工业学院
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TS743

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