【作者】 张绪燕；

【导师】 刘温霞；

【作者基本信息】 山东轻工业学院 ， 制浆造纸工程， 2010， 硕士

【摘要】 一维纳米材料因其独特的几何效应得到广泛应用。实验中利用水热法以二氧化钛和氢氧化钠为原料合成了带负电荷的钛酸钠纳米带和纳米管,对合成条件如温度和时间对产物的影响做了研究并对产物进行了表征。然后利用钛酸钠作为阴离子微粒,通过动态滤水仪和絮凝度分析仪研究其自身及与阳离子聚丙烯酰胺组成微粒助留体系时,对纸料和填料的助留、絮聚情况,并利用透射电镜分析钛酸钠纳米带助留体系的助留机理与特点,最后与纳米线状结构的碱式氯化镁的微粒助留作用进行了比较。结果表明,钛酸钠粒子为完整的结晶体,颗粒的形貌受温度影响较大,低温(150℃)下合成的产物为纳米管,长度约为1.5～5.0μm,纳米管的外径在30～70nm之间;高温(180℃)下合成的产物为纳米带,延长时间增加纳米带的长度和分布均一性。在180℃、72h的条件下合成的钛酸钠纳米带大部分在7μm左右,宽度在50～80nm之间。钛酸钠纳米带和纳米管都带负电荷,其Zeta电位在pH值4～6之间随pH值逐渐降低(绝对值增大),在pH值6～8之间几乎不变。钛酸钠纳米带和纳米管本身对填料的絮聚作用不大,但当与CPAM联合使用时在低加入量下表现出较好的协同絮聚作用,而且适当提高CPAM的量协同絮聚效果更好。CPAM/钛酸钠纳米带微粒助留体系更适用于中性抄纸,且絮聚作用具有桥联絮聚的特点。钛酸钠纳米带的长度对絮聚影响比较大,低加入量下长度越大越有利于对高岭土的絮聚。但长度大于一定值时因钛酸钠自身的团聚作用会抑制其絮聚作用。这一临界值为合成时间24h的钛酸钠纳米带,长度大约3μm左右。一定范围内增大CPAM加入后的剪切速率有助于钛酸钠纳米带对高岭土的重聚。无论是对高岭土还是对滑石粉,CPAM/钛酸钠纳米带、纳米管微粒助留体系引发的絮聚都具有较好的抗剪切能力,对高岭土作用形成的絮聚体比较致密。与球状纳米二氧化钛相比,钛酸钠纳米带和钛酸钠纳米管在低加入量下即可达到最佳絮聚效果,但纳米带整体絮聚效果不如纳米球状二氧化钛,纳米管与二球状氧化钛相差不大。与合成的线状碱式氯化镁相比,钛酸钠纳米带单独使用时絮聚效果不如线状碱式氯化镁,但当与CPAM联合使用时与碱式氯化镁的絮聚作用相差不大而且达到最大絮聚作用所需加入量及CPAM加入量都比较小。CPAM/线状碱式氯化镁与CPAM/钛酸钠纳米带或纳米管都属于微粒助留体系,增大CPAM加入后的转速有利于助留效果的提高,但是CPAM/线状碱式氯化镁微粒助留体系对滑石粉的絮聚有抗剪切能力较差。更多还原

【Abstract】 One-dimensional nanomaterials have been widely used because of their special geometry effects. In experiment, negatively charged sodium titanate nanobelt and nanotube were synthesized by a hydrothermal treatment of titanium dioxide in concentrated sodium hydroxide. The influence of temperature and time on the synthesis of the titanate nanomaterials was studied, and the products were characterized by TEM observation and zeta potentioal measurement. Then, the retention and flocculation effects of the sodium titante nanomaterials as a single coagulant and anionic microparticulate component with cationic polyacrylamide (CPAM) on fibers and fillers were investigated by means of dynamic drainage jar (DDJ) and photometric dispersion analyzer (PDA2000), respectively. The retention mechanisms and flocculation characters of the sodium titanate with CPAM were analyzed by transmission electron microscopy (TEM). Additionly, the flocculation effect of nanobelt was contrasted with that of titanium dioxide and magnesium hydroxide chloride hydrate nanowires either used alone or together with CPAM.Results indicate that the synthesized sodium titante one-dimensional nanomaterials are crystals and their morphology was inpacted greatly by temperaure. The product of lower temperature (150 oC) is nanotube with a typical length of 1.5~5.0μm and a diameter of 30 ~ 70 nm while the product of higher temperature (180 oC) is nanobelt, whose length and uniformity increased by postponding the reaction time. The length of most of the nanobelt is 7μm when time is as long as 72h. The width is 50~80 nm. In addition, it was found that the sodium titanate nanobelt and nanotube carried negative charges and their zeta potentials decreased as pH value increased from 4 to 6, but kept constant from pH 6 to pH 8.Both of sodium titante nanobelt and nanotube only cause a weak flocculation of kaolin clay. However, they show good synergistic effects with CPAM on filler flocculation at a very low dosage. Higher CPAM dosage give larger filler flocculation as the sodium titanate one-dimensional materials are employed as microparticle retention aids. In addition, they show higher flocculation effect with CPAM under neutral and weak alkaline conditions and induce filler flocculation with the character of bridging flocculation. The length of sodium titanate nanobelt has a great impact on flocculation. The flocculation of kaolin clay is inhanced as the length increased, but too long nanobelt is unfavorable to filler flocculation because of the aggregation of sodium titanate nanobelt. The titanate nanobelt with a reaction time of 24 h shows highest synergistic flocculation effect with CPAM on filler. Its length is 3μm. Furthermore, the filler flocculation induced by CPAM/titanate nanobelt or nanotube has a high shear resistance and the filler flocs are dense.Compared with spherical titanate dioxide, sodium titanate nanobelt and nanotube cause better clay flocculation at lower dosage as they used together with CPAM. However, nanobelt induces a weaker flocculation than titanate dioxide, while nanotube induces almost same flocculation with titanate dioxide at larger dosage. Comparing sodium titanant nanobelt with magnesium hydroxide chloride hydrate nanowires, it is found that the sodium titanate nanobelt induces a weaker flocculation of talc filler as used alone, but it induces a filler floculation nearly as strong as magnesium hydroxide chloride hydrate nanowires induces one as it used together with CPAM. Also, the sodium titanate nanobelt induces the maximum filler flocculation at a lower dosage and less CPAM addition level. Both magnesium hydroxide chloride hydrate nanowire and sodium titanate nanobelt and nanotube belong to micriparticle retention aid. Higher stirring speed after CPAM is immediately added, often results in higher final clay flocculation. However, the flocs induced by CPAM/magnesium hydroxide chloride hydrate nanowire have lower shear resistance.更多还原