【作者】 左椒兰；

【导师】 罗亚田；

【作者基本信息】 武汉理工大学 ， 环境工程， 2003， 硕士

【摘要】 为去除污水中悬浮污染物和重金属离子，大量性能优异的有机或无机絮凝剂应运而生。然而，大多数现有的絮凝剂或价格昂贵、或有微致毒性、或产生的残余污泥和残渣量大且难以处理处置，易对环境造成二次污染。因此，开发出无毒无害、无二次污染、残渣易处理回收的水处理剂已成为当务之急。 本文选定在水环境中易降解、无毒无害的天然高分子碳水化合物淀粉作为研究对象。在不改变淀粉固有特性的前提下，利用物理、化学或酶方法对其进行处理，改变其部分结构和性质制成改性淀粉。改性淀粉除对环境具有高度亲和力，还具有许多优异性能。鉴于目前对改性淀粉在水处理方面的应用研究不够深入，本论文通过试验研究了四类典型的改性淀粉，结论如下：（1）接枝共聚淀粉具有良好的絮凝性能，其中以淀粉—丙烯酰胺尤为突出。以玉米淀粉为原料，合成淀粉—丙烯酰胺，淀粉与丙烯酰胺的重量比为2.7：1，引发剂浓度为1×10^-3mol／L。pH值，反应温度对淀粉—丙烯酰胺的絮凝效果影响较小，在酸性或中性条件下水处理效果较好，与聚丙烯酰胺相比，淀粉—丙烯酰胺的絮凝效果略好。淀粉—丙烯酰胺对其它污水处理效果一般。（2）以广西明阳淀粉股份有限公司产品“CS—8”为代表的阳离子淀粉，能有效地絮凝高岭土和垃圾渗滤液中的悬浮物，但耗量偏大，适用范围偏窄。FNQE是在淀粉—丙烯酰胺的基础上加入添加剂合成，它的性能优于聚丙烯酰胺，可使城市污水COD去除率达到70-80％。添加剂FENTON试剂很重要，笔者经实验发现，单一的聚合铁就能将特难处理的垃圾渗滤液的COD去除80%以上。（3）交联淀粉黄原酸盐易合成，且成本较低，处理重金属废水有较好的效果。在pH=5左右时，黄原酸分子和离子各占50％的比例，大于5时主要是黄原酸离子，小于5时基本只有黄原酸分子。离子的吸附作用是主要机制，在pH值较大时效果显著，但不能排除氢氧化物的沉淀作用。交联淀粉黄原酸盐吸附沉渣中的重金属可通过硝酸回收。（4）氧化淀粉易合成，但对高岭土悬浮液及老龄化垃圾渗滤液几乎没有絮凝作用，可能是因为其分子量小，又呈负电性，缺乏吸附架桥和电性中和的能力。（5）改性淀粉絮凝机理和组分协同效应的研究还需加强，急需合成优异的改性淀粉来适应水处理的发展要求。 改性淀粉来源广，水处理效果在逐步提高，残渣一般无毒害。对其应用效果和应用成本的评价，必须以一个综合的环境效益和经济效益来衡量，相信改性淀粉将会更广泛地用于水处理。更多还原

【Abstract】 In order to wipe off the suspended pollutants and heavy metal ions in wasterwater, a great number of organic and inorganic flocculants have been synthesized. However,most of them are expensive, micro-toxic and the residual sludge is hard to dispose,which is an important source of second pollution.Thus,it is urgent to develop such a kind of water treatment agent that are non-toxic > clean and without second pollution.The paper selects starch as a candidate floccutant because it is a degradable, non-toxic, cleanjiatural organic compound.In experiments,the structure of starch is modified in part with physical,chemical and enzyme methods on the basis of keeping up starch’s inherent properties.The modified starch has good performance in flocculation besides it has high attraction to environment. Given that the related study is superficial,the paper analyzes the flocculation effect of four classical modified starch.The conclusions are as follows: l)The graft copolymer of starch with acrylamide has good performance hi flocculation. The raw material is corn starch, weight rate of com starch to acrylamide is 2.7:1 and the concentration of initiator is lx10-3mol/L. pH value, reacting temperature have little influence on flocculant of graft copolymer of starch with acrylamide.2) Cationic natural polymer modified starch "CS-8’ produced by Mingyang Starch Corporation hi Guangxi province can treat landfill leachate efficiently when hi high concentration. Experimental results indicate obvious flocculate character of CS-8 on kaolin . FNQE is synthesized by putting cationic additives into the parents fraction-starch-acrylamide graft copolymer. The experimental results show that FNQE has ideal turbidity removal efficiency and its performance is superior to that of polyacrylamide. Focusing on municipal wastewater, COD removal ratio is above 70-80% with FNQE. Polymer iron can remove landfill leachate COD 70%-80% with a little additive-Fenton reagent.3)Synthesis of cross-linking starch xanthate is easier than other modified starch.and the cost is less too. When pH is 5 or so ,molecules and ions of xanthate account for 50%respectively .While pH is above 5, the major effect is from ions, or from raolecules-Meanwhile hydroxides’ action in the process of precipitate is hidden. Furthmore, the precipitates containing heavy metals can be leached with nitric acid to recover the heavy metals. 4) The process of synthesizing oxidized starch is simple. It almost can’t flocculate suspended pollutants.Its lack of adsorbability maybe arises from its small molecules and negative charge, and ferior bridge function.5) Research on action mechanism of modified starch and coordination effect on different components should be strengthened. How to synthesize excellent modified starch so as to suit for water treatment is urgent.Due to wide resources, gradually improving effect and low residual toxicity of starch, evaluation on modified starch in effect and cost must rely on comprehensive environmental and economic profits. Modified starch can be believed to have wide perspective in the field of waste water treatment as flocculent and sorbents of heavy metals.更多还原