氢氧化铝—聚丙烯酰胺杂化材料的制备和稀溶液行为及其絮凝性能研究

【作者】 杨骛远；

【导师】 沈之荃； 钱锦文；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2005， 博士

【摘要】 有机-无机杂化材料既具有无机物的性能,又兼备有机材料的优点,已引起人们的广泛关注。在用于水处理的各类絮凝剂中,复合絮凝剂被认为是未来絮凝剂的发展方向之一。基于前期对无机/有机复合絮凝剂的系统研究,本论文设计合成了离子键型和共价键型无机—有机杂化絮凝剂。 采用原位聚合法制备了一类无机—有机离子键型杂化絮凝剂:氢氧化铝—聚丙烯酰胺离子键型杂化絮凝剂（I-hPAM）和坡缕石—聚丙烯酰胺离子键型杂化絮凝剂（I-hMPAM）。采用¹H-NMR、瓜、粘度、电导、SEC、TEM和TGA等手段对离子型杂化絮凝剂进行了表征,表明得到的杂化物是离子键结合的星型结构的杂化PAM。系统考察了氢氧化铝的粒径、含量对原位聚合的影响,发现在原位聚合的过程中,随氢氧化铝胶体粒径的增大,I-hPAM的特性粘数先升高而后下降;随氢氧化铝胶体用量增加,I-hPAM的特性粘数则降低。 采用氢氧化铝与一缩二乙二醇酯化反应所得的氢氧化铝—一缩二乙二醇杂化物（HDA）与Ce⁴⁺盐组成氧化还原引发体系,引发丙烯酰胺原位聚合制备了氢氧化铝—聚丙烯酰胺共价键杂化物（C-hPAM）;引发丙烯酰胺与氯化二甲胺氧乙基丙烯酸酯（DMC）共聚合,获得了阳离子型共价键杂化聚丙烯酰胺（C-hCPAM）。采用¹H-NMR、IR、粘度、电导、TEM和TGA法等手段对杂化物进行了表征,表明杂化物是一种无机—有机相间以共价键相连的星型结构的杂化物.考察了HDA对丙烯酰胺原位聚合的影响,发现随HDA中氢氧化铝粒径的增加,C-hPAM的分子量降低,以及某一最佳HDA用量时可获最大分子量的C-hPAM。 采用粘度法对氢氧化铝—聚丙烯酰胺杂化物的稀溶液性质进行了系统研究。发现在稀溶液状态下,与纯聚丙烯酰胺不同,杂化聚丙烯酰胺的粘度行为偏离Huggins方程。即,离子型杂化聚丙烯酰胺I-hPAM的η_sp/C～C曲线呈向下弯折（Downturn）。并研究了I-hpAM杂化物的分子量、氢氧化铝粒径和含量等因素对稀溶液粘度偏离行为的影响,发现η_sp/C～C曲线开始下折时的浓度C-d,随杂化物中氢氧化铝粒径和含量增加而增大,随杂化物分子量升高而降低。而共价键型杂化聚丙烯酰胺C-hPAM的刚η_sp/C～C曲线则呈向上弯折（Upturn）,相反于I-hPAM杂化物的稀溶液粘度行为,但类同于多臂星型聚合物和树状高分子的溶液粘度行为。系统考察了C-hPAM杂化物的分子量、氢氧V浙江大尝博士李位伦友亩亩目自亩亩亩亩‘‘亩.....化铝粒径和含量等因素对稀溶液粘度偏离行为的影响,发现nsv/C一C曲线开始上弯时的浓度Cu,随杂化物中氢氧化铝含量增大而升高,随杂化物分子量和氢氧化铝粒径增大而降低。 采用电导法和SEC研究了杂化聚丙烯酞胺在稀溶液中的电离行为。发现C.llPAM的K一C关系曲线呈线性行为,即在稀溶液中不发生电离。但I.hPAM和1.加过R叼边的K一C关系曲线呈非线性行为,存在似平台区。若定义K^C曲线开始呈平台时的浓度为Ck,则发现I一址城M杂化物的分子量、氢氧化铝粒径和含量等因素对Ck的影响规律十分类同于对Cd值的影响规律。在研究1.班叭M和I.hN田AM离子型杂化物的SEC谱图的进样始浓度依赖性时发现,低进样始浓度会导致其SEC谱出现明显的多峰和肩峰,这是其电离及星型结构特征所致。由此表明,离子键型杂化物稀溶液粘度的异常行为是由其电离所致。 考察各类杂化PAM絮凝剂处理高岭土悬浮液,发现其絮凝效果存在最佳无机用量以及无机粒子的粒径越小,则絮凝效果越好的规律。对五种分别带有不同链末端基的聚丙烯酞胺（PAM,s住理.PAM,I一班叭M,1.bJ城R划随和C七PAM）的絮凝效果进行比较,发现在相同实验条件下,絮凝效果按上述顺序依次变好,杂化絮凝剂絮凝形成的球状絮体较纯聚丙烯酞胺的松散的线团状絮体更密实。在相同加量下,C.hPAM的絮凝效果较纯PAM提高2倍以上,形成的絮体的抗剪切稳定性提高3倍以上。同时,还考察了阳离子型共价键杂化聚丙烯酞胺（C一hCPAM）对高岭土废水的絮凝效果,发现C一hCPAM最佳用量比纯阳离子聚丙烯酞胺（C pAM）减少了50%,而最佳絮凝效果却比CPAM絮凝剂的提高了30%。将C一hCPAM用于处理实际废水其絮凝效果也明显优于CPAM絮凝剂。 应用高分子溶液的团簇理论阐明高分子絮凝剂的絮凝机理,发现稀溶液中高分子链团簇的形成是产生最佳絮凝的必要条件。对杂化絮凝剂的絮凝机理进行了初步探索,认为杂化PAM的杂化结构既有利于发挥无机絮凝剂的电中和、吸附及有机絮凝剂的架桥作用,又有利于聚合物链团簇的形成。基于高分子溶液的团簇理论和实验及文献絮凝数据的分析,提出了高分子絮凝剂最佳添加量（Cod）、高岭土悬浮液浓度（Css）及高分子稀溶液动态接触浓度（cs）之间定量线性关系式,Cod二5.74xl少（C s.css）“一3.1。揭示了高分子稀溶液分子链的聚集状态与絮凝效果之间的内在联系。 关键词:聚丙烯酞胺氢氧化铝有机一无机杂化物絮凝剂粘度团簇更多还原

【Abstract】 Four kinds of organic-inorganic hybrid flocculants, i.e., ionic hybrid of Al(OH)3-polyacrylamide (I-hPAM), ionic hybrid of modified palygorskite - polyacrylamide (I-hMPAM), covalent hybrid of Al(OH)3-poiyacrylamide (C-hPAM) and covalent hybrid of Al(OH)3-cationic polyacrylamide (C-hCPAM) , have been synthesized respectively. The hybrids were characterized with 1H-NMR, IR spectrum, viscosity, conductivity, size exclusion chromatography (SEC), TEM and TGA. It was found that the hybrids above could be star-like hybrids.Two kinds of ionic hybrids have been prepared in different ways. The I-hPAM flocculants have been synthesized using a redox initiation system ((NH4)2S2O8/NaHSO3) by in-situ polymerization of acrylamide in aqueous medium of colloidal Al(OH)3. The I-hMPAM flocculants have been synthesized by in-situ polymerization of acrylamide using heterogeneous redox initiator system, composed of ethanolamine modifying palygorskite together with oxidant Ce4+. It was found that ionic bond formed between inorganic particles and polyacrylamide, i.e., PAM with negative chain end(-SO42-) bonding to the positive particle of Al(OH)3 colloid in I-hPAM and PAM with positive chain end(NH3+) bonding to palygorskite with O in I-hMPAM . Dilute solution viscosity behaviors of ionic hybrids have been studied. The reduced viscosity (sp/C) ~ concentration (C) curve of the I-hPAM has been found having a discontinuity or downturn at low concentration region. This discontinuity phenomenon is accounted for assuming ionization of the ionic hybrid PAM. Studies on conductivity behavior and incipient concentration dependence of SEC graph for I-hPAM and I-hMPAM support the ionization of the ionic hybrids in the dilute solution.C-hPAM hybrid has been synthesized by polymerization of acrylamide using a redox initiation system of Al(OH)3-diglycol hybrid / Ce4+. Characterizations showed the covalent bond between Al(OH)3 and PAM in the hybrid. Dilute solution viscosity behavior of C-hPAM has been studied. The reduced viscosity (sp/C) ~ concentration (C) curve of the C-hPAM has been found having a discontinuity or upturn at low concentration region same as the star-like polymer.Five kinds of flocculants with different chain end groups (PAM, star-PAM, I-hPAM, I-hMPAM and C-hPAM hybrids) have been used. The flocculation behavior for 0.25wt% kaolin suspension was evaluated by spectrophotometer and phase contrast microscope (PCM). It was found that their flocculation efficiencies decease in the following order: C-hPAM>I-hMPAM>I-h-PAM>star-PAM>PAM. Also, the hybrid flocculants showed less shear sensitivity and give more dense flocs than pure PAM. Much better flocculation of hybrid flocculants was attributed to the synergism of the inorganic particle and polymer, which act as the charge neutralization or adsorption and bridging respectively. In addition, the hybrid flocculants were used to treat mixture of domestic and industrial wastewater. The result shows that hybrid flocculants are promising flocculants in wastewater treatment.The cluster theory of polymer solution was first applied to explain the mechanism of flocculation. It was found that the optimal dose (Cod) of polymer flocculants is proportional to the dynamic contact concentration (Cs) of polymer flocculants and to the suspension solid content (Css) in kaolin suspensions, i.e., Cod = 5.74×104(Cs·Css) 0.5—3.1. The result shows that it is important to form the polymer clusters in dilute solutions for reaching the best flocculation.更多还原