【作者】 郝学奎；

【导师】 常青；

【作者基本信息】 兰州交通大学 ， 环境工程， 2009， 博士

【摘要】 本文以玉米淀粉为基体,首先在弱碱性条件下,用环氧氯丙烷(EPI)作交联剂与玉米淀粉作用生成交联淀粉(CSt),然后在弱酸性条件下,以硝酸铈铵(CAN)为引发剂、丙烯酰胺(AM)为单体,合成交联淀粉-丙烯酰胺接枝共聚物(CSA),最后此接枝共聚物和二硫化碳在碱性条件下磺化生成具有捕集重金属功能的高分子絮凝剂-----交联淀粉-聚丙烯酰胺-黄原酸酯(Crosslinked Starch-graft-polyAcrylamide-co-sodium Xanthate,简称CSAX)。用FTIR光谱、元素分析、电子扫描电镜以及X射线能量色散谱仪等对CSt、CSA、CSAX进行了表征。并讨论了环氧氯丙烷的用量,硝酸铈铵的剂量,NaOH和二硫化碳的重量百分比、温度、时间等合成条件对产品性能的影响。因为在CSAX分子中同时含有聚丙烯酰胺侧链和黄原酸基,所以CSAX具有同时除浊和捕集重金属离子双重功能。通过实验室配水和实际生产废水的絮凝实验,证明CSAX具有良好的絮凝功能,为重金属废水的治理提供了一种新的方法,开辟了一剂多用的途径,可望减少水处理的单元数,或者降低处理负荷和成本,使重金属离子的处理变的简单易行。论文的实验研究主要包括以下六部分内容：一)研究了交联淀粉的制备条件对CSAX性能的影响。实验证明最佳合成条件为：玉米淀粉50 g,1% (w/v) NaCl溶液75 mL,15% (w/v) NaOH溶液20 mL,环氧氯丙烷4 mL,反应时间8 h,反应温度30℃,获得交联淀粉的沉降积为45 mL。二)研究了交联淀粉-丙烯酰胺接枝共聚物的制备条件及对CSAX性能的影响。实验证明最佳合成条件为：交联淀粉40 g/L,丙烯酰胺的浓度为0.939 mol/L,硝酸铈铵的浓度为6.67×10-4mol/L,反应时间3 h,反应温度45℃,此时CSA的接枝率和接枝效率均较高,分别为86.6%和72.7%,侧链的分子量可达2.64×107。三)研究了交联淀粉-聚丙烯酰胺-黄原酸酯的制备条件及对CSAX性能的影响。实验证明在催化剂NaOH浓度为3 mol/L,交联淀粉-丙烯酰胺接枝聚合物浓度为50 g/L, CS2浓度为1.6mol/L,反应温度为30℃,反应时间为3h的条件下,产品CSAX中的硫含量较高,为7.41%。四)研究了CSAX絮凝性能。在实验中分别用CSAX处理了含铜、铬、镍、汞以及多种金属离子的实验室配水和兰州综合电镀厂的生产废水。实验结果表明在实验室配水条件下,无论是水样含一种金属离子还是多种金属离子,CSAX对其都有较好的去除能力。用CSAX处理兰州综合电镀厂的生产废水,其表现为对重金属离子Cu2+、Pb2+、Cd2+有较高的去除能力,但对Cr(Ⅵ)、Ni2+、Zn2+的去除不显著。五)对CSAX形成絮体形态的研究表明,絮体的表面和内部具有高度不规则性,絮体的形成过程具有分形特征。通过实验研究絮体的特性和分形维数之间的关系,分析了絮体的分形特征,在原水浊度为100 NTU, pH值为5.0,Cu2+的浓度为25mg/L, CSAX的投加量为30mg/L的条件下,CSAX的絮凝效果最好,形成絮体的分形维数为2.0。证明可以通过监测絮体的分形维数来监控絮凝过程。六)探讨了CSAX的稳定性和技术经济。表明CSAX在低温、避光的条件下,存放稳定性较好,基本不会影响对废水的处理效果；另外,CSAX的生产成本低,处理废水时操作简单,处理效果好,可产生较好的社会效益和经济效益。更多还原

【Abstract】 A novel macromolecule flocculant with the function of trapping heavy metal ions has been synthesized by using corn starch as matrices. Firstly, starch (St) was crosslinked by using epichlorohydrin (EPI) as cross-linking reagent under the basic conditions; then the crosslinked-starch-grafted-polyacrylamide of copolymer (CSA) was synthesized by using ceric ammonium nitrate (CAN) as initiator and acrylamide (AM) as monomer under the weak acid conditions; finally the new kind of flocculant called crosslinked starch-graft-polyacrylamide-co-sodium xanthate (CSAX) was synthesized by xanthation of the copolymer under the basic conditions. The structures of crosslinked starch (CSt)、CSA、CSAX were characterized with fourier transform infrared spectroscopy (FTIR), elemental analysis, scanning electronic microscope (SEM), and Energy dispersive X-ray spectrometry (EDS). The effects of the preparation conditions, such as the dosage of EPI and CAN, the percentage by weight of NaOH and CS2, reaction temperature and reaction time etc, were investigated. Because of CSAX molecules containing both the PAM pendant chains and—(?)—S, the CSAX was endowed the double functions of removing turbidity and trapping heavy metal ions. It can be found that there were excellent flocculantion functions of CSAX through flocculantion test of laboratory water and factory effluent. It could offer a new method for the heavy metal wastewater treatment, set a new approach for one dosage multi-usage, decreased the treatment units and cost, and made the treatment of heavy metal ions simpler and easier.There were mainly six sections of experimental studies in the thesis:1. Synthesis of crosslinked starch and the effects of some factors, such as the dosage of reactant and initiator, reaction time, reaction temperature, crosslinking degree on the performance of CSAX, were investigated. The results showed that the optimal synthesis conditions are:corn starch of 50 g, NaCl of 75 mL (1%, w/v), NaOH of 20 mL (15%, w/v), EPI of 4 mL, at 30℃for 8 h, SV (sediment volume of CSt) of 45 mL. In order to form solid-liquid separation effectively in flocculation, the crosslinking degree can not be too high.2. Synthesis of crosslinked-starch-grafted-polyacrylamide of copolymer (CSA), and the effects of some factors, such as the concentration of monomer and initiator, reaction time, reaction temperature, grafting percentage, efficiency of grafting, molecular weight of grafted PAM pendant chains on the performance of CSAX, were investigated. The results showed that the optimal synthesis conditions are:the concentration of CSt, AM and CAN is 40 g/L, 0.939 mol/L and 6.67×10-4 mol/L, respectively, at 45℃for 3h. So the grafting percentage is 86.6%, the efficiency of grafting is 72.7%, and the molecular weight of grafted PAM pendant chains reaches 2.64×107. 3. Synthesis of crosslinked starch-graft-polyacrylamide-co-sodium xanthate (CSAX), and the effects of some factors, such as the material ratio, reaction time, reaction temperature on the performance of CSAX, was investigated. The results showed that the optimal synthesis conditions are:the concentration of CSA, NaOH and CS2 is 50 g/L,3.0 mol/L and 1.6 mol/L, respectively, at 30℃for 3 h. So the percent of S reaches 7.41%. As proven by FTIR, elemental analysis, and SEM, the CSAX can be successfully synthesized and can remove both turbidity-causing substances and heavy metal ions from aqueous solutions.4. The flocculation performance of CSAX was studied. It was treated in experiment by CSAX that the laboratory water containing Cu2+、Cr3+、Ni2+、Hg2+ or manifold heavy metal ions and actual electroplating wastewater of Lanzhou special electroplating. The results showed that CSAX exhibits the better removal capacity, either laboratory water containing one or manifold heavy metal ions. If actual electroplating wastewater of Lanzhou special electroplating is disposed by CSAX, Cu2+、Pb2+、Cd2+ are removed the better than that of Cr(Ⅵ)、Ni2+、Zn2+5. The microscopic studies of CSAX flocs indicated that CSAX flocs’ surface and interior presented highly irregularity. The research also indicated that CSAX flocs’ structure and establishment possessed fractal characteristics. The waste water containing both Cu2+ and Kaolin was treated with CSAX in flocculation experiment; the relationships between flocs’ characteristics and fractal dimension were studied. The fractional dimension of the floc was calculated to be 2.0 in the best flocculation. It was almost certain that we could control the flocculation process by meteraging of the flocs’ fractal dimension.6. Stabilization of product and technical economical analysis were discussed. It can be seen that CSAX has better stabilization at the lower temperature and light-proof, and the treatment efficiency for heavy metal will be less affected. In addition, CSAX provided with low operating cost, simple treatment method, and higher efficiency. Therefore, it has a good social and economice benefit.更多还原