高分子量聚丙烯酰胺地合成

1、高分子量高纯度阳离子聚丙烯酰胺的合成Synthesis of a cationic polyacrylamide with highmolecular weight and high purity背景： 阳离子聚丙烯酰胺絮凝剂作为有机高分子絮凝剂已被广泛应 用于污泥脱水工业废水及市政污水的处理。目前，阳离子聚丙烯酰 胺系列产品絮凝剂在美国日本欧洲各国的用量已占有机絮凝剂总量 的75%80%。近年来，国对阳离子聚丙烯酰胺系列絮凝剂的市场 需求在不断增加，但在应用方面，大多局限于污水及污泥处理，用 于饮用水源处理的研究较少 ; 在使用过程中，存在价格昂贵缺乏成品 的质检和有效的卫生监控等问题，使得

2、絮凝剂的卫生安全存在较大 隐患。在一些情况下和一定围，阳离子聚丙烯酰胺的分子量越大，处 理效果越好 阳离子聚丙烯酰胺对原水处理中部分常规处理工艺难以 去除的有机污染物有较好的去除效果，但由于聚丙烯酰胺产物中存 在未聚合的丙烯酰胺单体，丙烯酰胺是一种水溶性具有神经毒性和 遗传毒性的致癌物，极大的限制了其在原水处理中的应用 目前，国 对聚丙烯酰胺的研究大多仅停留在如何提高聚合物的相对分子质量， 对如何降低聚合物中残留单体含量的研究较少 因此，为了满足国市 场对高纯度高分子量絮凝剂的需求研究降低阳离子聚丙烯酰胺中残 留丙烯酰胺含量同时又保证合成高分子量的聚合物合成适用于饮用 水源水处理的有机高分子絮

3、凝剂具有重要的意义。1.1高分子量聚丙烯酰胺的定义聚丙烯酰胺( Polyacrylamide ， PAM )是丙烯酰胺及其衍生的 均聚物和共聚物的统称。聚丙烯酰胺的分子量有低、中、高和超高 之分，一般来说， 100万以下为低分子量、 100 万-1000 万为中低分 子量、1000 万以上高分子量。所以高分子量聚丙烯酰胺是分子量在 1000万以上有机高分子聚合物。1.2高分子量聚丙烯酰胺的分子结构高分子量聚丙烯酰胺的分子结构为：' CH2=CH :丨JC0NH2结构式中丙烯酰胺分子量为71.08, n值为2X 1049X 105，故聚丙烯酰胺分子量一般为1.5X 1066X 107。1

4、.3高分子量聚丙烯酰胺的分类根据PAM大分子链上官能团在水溶液中的离解性质，可划分 成阴离子型（CPAM）、阳离子型（APAM ）、非离子型（NPAM ） 及两性离子型几个品种。阳离子型一般都含有微量毒性，不适宜在 给排水工程中使用，所以我们接触到的水处理剂聚丙烯酰胺均属阴 离子型或非离子型。根据高分子量聚丙烯酰胺的纯度产品来分，有粉剂和胶体两种，粉剂产品为白色或微黄色颗粒或粉末，固含量一般在90%以上，胶体产品为无色微黄色透胶体，固含量为8%9%。1.4高分子量聚丙烯酰胺的特点高分子量聚丙烯酰胺因其结构单元中含有酰胺基、易形成氢键， 使其具有良好的水溶性和很高的化学活性，可通过接枝、交联等反

5、 应得到多种衍生物。高分子量聚丙烯酰胺是由丙烯酰胺单体聚合而成的有机高分子 聚合物，无色无味、无臭、易溶于水，没有腐蚀性。高分子量聚丙烯酰胺在常温下比较稳定，高温、冰冻时易降解, 故其贮存与配制投加时，温度应控制在 2C55C时。2.1高分子量PAM的合成方法简介目前，PAM的合成方法根据聚合是否加入其他单体，又可分为 均聚和共聚2种，PAM产品形态有水溶液、乳剂和粉剂等。国外常 用的AM聚合方法有水溶液聚合法，反相乳液聚合法，悬浮聚合法等, 其基本原理都是基于 AM在引发剂的作用下，进行自由基引发聚合，生 成聚丙烯酰胺，反应式如下：7琏引发：CIICOM J 2V-HR*R CII2 丫 *

6、CON IT 2¥链增长反应：- CH2=CONH；RIH 厂'一CHLLCONH： CONH：IICOXFhCONH：H锌终止反应:CH:COXHiIICONHj吹1H （CHiCH: yCH:COXH?CONHpONHi3* 1CON H ：IIIICQXU：歧化终止CONH：+，fCHzCON II2CONIh CONIh由上式可知AM聚合过程中链增长，链引发及链终止反应符合自 由基引发聚合的一般规律，故AM的聚合反应为自由基引发聚合反应。2.2水溶液聚合法水溶液聚合法是将单体 AM和引发剂溶解在水中的聚合反应， 是目前应用较广泛和成熟的技术。所得 PAM产品有胶状和粉

7、状2种, 其胶体采用质量分数为8%-10%或20%-30% AM的水溶液在引发剂 作用下直接聚合而得，产物经脱水干燥后可得粉状产品。产物相对 分子质量为7万-700万。该法优点为安全、工艺设备简单、环境污 染小，缺点是产物固含量低，仅为8%-15%，且易发生酰亚胺化反应，生成凝胶。在PAM的水溶液聚合中，引发剂在很大程度上决定了聚合反应 后得到产物的相对分子质量、产率，因而新型引发体系的开发是 AM水溶液聚合研究的关键。2.3反相乳液聚合法丙烯酰胺单体配制成浓度为 30%60%的水溶液作为分散相， 其中加有少量的二乙胺四乙酸和Na2SO4以及氧化一还原引发剂和适量水溶性表面活性剂，其 HLB值

8、应较低。用芳烃或饱和脂肪烃作 为连续相，其中加有油溶性表面活性剂，其HLB值应较高，如脱水 山梨醇油酸酯。Na2SO4具有防止胶乳粒子粘结的作用。分散相与连 续相的比例通常为3:7。聚合所得分散相胶乳粒子直径为 0.110卩m, 与表面活性剂用量有关。反应温度一般为 40 C 6 h转化率可达98%。 此法的优点是反应热易导出，物料体系粘度低，便于操作，产品可 不经干燥直接应用。缺点是使用有机溶剂，易燃、有效生产能力低 于溶液聚合法。2.4反相悬浮聚合法反相悬浮聚合是近几年发展起来的新方法。反相悬浮聚合法生 产土艺简单、成木低，易十实现土业化，产品相对分子质量可达千 万以上，溶解性能比水溶液聚

9、合产品好，可直接得到粉状或粒状产 品，包装和运输方便。2.5新的聚合方法近年来对PAM合成中自由基引发方式的研究有了新进展，采用 更为节能环保的引发体系，如光引发聚合、热引发聚合、辐射聚合、 等离子体引发聚合、沉淀聚合、胶束聚合等。Syn thesis of a cati onic polyacrylamide with highmolecular weight and high purityBackground: cationic polyacrylamide flocculant as an organic polymer flocculant has bee n widely appli

10、ed in the process ing of in dustrial wastewater and muni cipal sewage sludge dewateri ng. At prese nt, the cati onic polyacrylamide floccula nt series products in the Un ited States Japa n the dosage of the Europea n coun tries have accounted for 75% 80% of the total organic flocculant. In recent ye

11、ars, the domestic market dema nd of cati onic polyacrylamide floccula nt series are on the in crease, but in terms of application, are mostly limited to sewage and sludge treatment, and less research for drinking water treatme nt; In use process, there is expe nsive lack of finished product quality

12、and effective health monitoring, etc., makes flocculant health security there is a big hidde n trouble.In some cases, and a certain range, the higher the molecular weight of the cationic polyacrylamide, the better the treatme nt effect cati onic polyacrylamide in raw water treatme nt is part of the

13、conven tio nal treatme nt process is difficult to remove theorga nic polluta nts has better removal effect, but as a result of polyacrylamide products, did not exist in the polymerization of acrylamide monomer acrylamide is a kind of water-soluble carci nogens with n eural toxicity and gen etic toxi

14、city, greatly limits its application in the raw water treatment at present, the domestic study of polyacrylamide are mostly just stay on how to improve the polymer relative molecular mass, the study of how to reduce the residual mono mer content in polymers less, therefore, i n order to meet domesti

15、c market dema nd for high purity high molecular weight floccula nts research to reduce residual acrylamide content in cati onic polyacrylamide again at the same time to ensure that the synthesis of high molecular weight polymer synthesis is suitable for drinking water supply in water treatment of or

16、ganic polymer flocculant has the vital significanee.1.1 the definition of high molecular weight polyacrylamidePAM (Polyacrylamide, PAM) acrylamide and its derivatives of homopolymer and copolymer. Molecular weight of polyacrylamide with low, medium, high and ultra- high, in general, for low molecula

17、r weight below 1 million, 1 million -10 million as the low molecular weight, high molecular weight more than 10 million. So the high molecular weight polyacrylamide is over 10 million organic polymer molecular weight.1.2 the molecular structure of the high molecular weight polyacrylamideThe molecula

18、r structure of the high molecular weight polyacrylamide is:-CH2 CHT ICONH2Structural formula of acrylamide molecular weight is 71.08, the value of n for the 2 x 104 9 x 105, so the polyacrylamide molecular weight average of 1.5 x 106 6 x 107.1.3 the classification of high molecular weight polyacryla

19、mideAccord ing to PAM dissociati on properties of functional group in aqueous solutio n, macromolecular chain can be divided into ionic colorful (CPAM), cationic (APAM), nonionic (NPAM) and amphoteric ionic several varieties. Cati onic gen erally contain traces of toxicity, not suitable for use in w

20、ater supply and drain age engin eeri ng, so wecome into con tact with the water treatme nt age nt bel ong to the anionic and nonionic polyacrylamide.Accord ing to the purity of high molecular weight polyacrylamide products, has two kinds of powder and colloid, powder product is white or light yellow

21、 granu lar or powder, solid content is in commonly 90%, colloidal gel product is a colorless, yellowish, solid content is 8% 9%.1.4 the characteristics of high molecular weight polyacrylamideHigh molecular weight polyacrylamide because of its structural unit containing amide, easy to form hydrogen b

22、onding, make it has good water solubility and high chemical activity, can be obta ined by graft ing and crossli nking reacti ons such as a variety of derivatives.High molecular weight polyacrylamide is composed of acrylamide mono mer polymerization of organic polymer, colorless, tasteless, odourless

23、, soluble in water, no corrosi on.High molecular weight polyacrylamide is stable at room temperature, high temperature, easy degradati on, whe n froze n so its storage and preparati on for overtime, temperature should be con trolled withi n 2°C 55 °C .2.1 the syn thesis of high molecular w

24、eight PAMAt prese nt, the syn thesis methods of PAM accord ing to whether aggregati on will join other monomer, can divide again homopolymerization and copolymerization, PAM product form a aqueous solution, emulsion, and powder, etc. AM polymerizati on methods com monly used at home and abroad with

25、aqueous soluti on polymerizati on, inv erse emulsi on polymerizati on, suspe nsion polymerizati on and so on, its basic principle is based on AM in under the action of the initiator, carries on the free radical polymerizati on, gen erate polyacrylamide, equati on is as follows:7Y琏引发：di 2=+ R RCH 2Cj

26、： *CON H2CON 1T 2锥增长反应：R CH C + CH7= CRCCH2(-COXIhCONHiCONH? CONH:COX HaII+ “口【门+CH：= CCOMH?链终止反应:一C止VCOXHH >1CONH? CONHj复書剣：ifcjciaconhF°wdHHHH III歧化般【rII CH 厂y+ CUzchH + =cCONII： CONHzCONIh CON II：By type known AM cha in polymerizati on process, the cha in in itiati on and term in ati on r

27、eacti on accords with the gen eral law of free radical polymerizati on, the polymerizati on react ion of free radical polymerizati on react ion of reas on AM.2.2 aqueous solution polymerizationAqueous soluti on polymerizati on mono mer AM and in itiator of polymerizati on, dissolved in the water is

28、widely used and mature tech no logy. The PAM gel and powder products, the colloid by mass fracti on is 8% - 10% or 10% - 30% aqueous solution of AM direct polymerization under the action of a initiator and, after drying can be powder product. Product molecular weight is 70000-7 milli on. The adva nt

29、ages of safety, simple process equipme nt, en vir onmen tal polluti on is small, the disadva ntage is that the product solid content is low, only 8% - 8%, and prone to imide reacti on, gen erate gel.In the PAM aqueous solution polymerization, the initiator to a great extent, determ ines the relative

30、 molecular mass of the product result ing from the polymerizati on react ion, yield, and the developme nt of the new in itiator system is the key to AM aqueous soluti on polymerizati on research.2.3 in verse emulsi on polymerizati onAcrylamide mono mer mixture concen trati on is 30% 60% aqueous solu

31、ti on as the dispersed phase, which add a small amount of diethylam ine tetraacetic acid andNa2SO4 and oxidation - reduction initiator and right amount water soluble surfactant, the HLB value should be lower. With aromatic hydrocarb ons or saturated hydrocarbons as continuous phase, which is oil sol

32、uble surfactant, the HLB value should be higher, such as dehydration, sorbitan oleate. Na2SO4 have prevent the latex particle bonding effects. The proporti on of the dispersed phase and con ti nu ous phase is usually 3:7. Aggregate in come dispersed phase latex particles was 0.1 10 microns in diameter, related to the dosage of surface active age nt. React ion temperature is com monly 40 °C 6 h conv ersi on rate could reach 98%. This method has the adva ntage of heat of react ion is derived, and