【作者】 邢佶勇；

【导师】 张爱丽；

【作者基本信息】 大连理工大学 ， 环境工程， 2005， 硕士

【摘要】 壳聚糖是一种天然有机高分子絮凝剂,具有无毒、无害、生物相容性和多功能性等特点,有着广泛的应用前景。本文建立了静态浸润法制备壳聚糖的新工艺,同时优化了新的工艺条件,并对壳聚糖分子量的测定方法进行了规范;在此基础上,对工艺废水进行了资源化处理研究;并考察了壳聚糖自身品质以及外部条件对其絮凝性能的影响。其主要结果与结论如下: ①采用静态、浸润法脱乙酰基制备壳聚糖的最佳条件:1g甲壳素与70%浓度（m/v）NaOH溶液5mL（v/v=1:1）,无搅拌,118℃反应4小时,制得脱乙酰度（D.D值）78±3%,分子量6x10⁵的壳聚糖。此方法与传统工艺相比,可节省浓碱用量近70%,且无需机械搅拌,大大降低了生产成本,有着良好的经济、环境、社会效益。 ②配制的壳聚糖原溶液初始浓度不同,测出的粘度分子量也不同,当壳聚糖溶液浓度在0.05g/50mL—0.2g/50mL范围时,测定的壳聚糖分子量比较稳定。 ③对废碱液进行回收利用,回收了工艺废水中的蛋白质和氢氧化钙,降低了工艺成本;将生产排放的废液依次经过混凝、VTBR二级生化处理、Fenton试剂氧化使出水COD小于100mg/L,澄清透明,再经过反渗透除盐处理可作为工艺洗涤水回用,做到了经济与环保的双赢。 ④壳聚糖脱乙酰度和分子量的提高有助于降低其用量。但壳聚糖脱乙酰度增加到75%后,达到相同絮凝效果时投加量的降低程度很小;考虑到高脱乙酰度的壳聚糖制备成本也高,作为絮凝剂,壳聚糖脱乙酰度大于75%即可。脱乙酰度对壳聚糖絮凝性能的影响远远高于分子量的影响。 ⑤壳聚糖不论对于低浓度痕量含Cu²⁺废水还是高浓度的含Cu²⁺废水,均有很好的絮凝效果,去除率都在90%以上。对于低浓度含Cu²⁺废水壳聚糖絮凝以螯合作用为主;对于高浓度的含Cu²⁺废水壳聚糖絮凝以吸附架桥为主。更多还原

【Abstract】 Chitosan is one of the natural polysaccharide flocculants. Advantages of Chitosan, such as harmless, living compatibilities and multi-function, made it promising in application. Therefore, research works carried out on chitosan have become popular recently. This paper develops a new method of the preparation of chitosan in which deacetylation of chitin under immersed-static conditions is evaluated and the produce-craft of Chitosan is modified as well. This paper also strengthens its stability of measured value by improving the measurement of chitosan mass-weight. Further more, research on how different factors influenced the flocculant capabilities of chitosan will be provided.The key findings of this paper include:①Deacetylation of chitin under immersed-static conditions (solids/solvent ratio (v/v)=l:l;no agitating;with70%NaOH;118℃ for 4h) is evaluated for the preparation of chitosan. The results indicate that this approach can reduce the dosage of the exhausted alkaline approximately 70%. Treated chitosan shows similar degree of deacetylation (78 ±3%), but significantly higher molecular mass (6x105) compared with those of the commercial chitosan. Comparing with the traditional craft, this method does not need the machine agitation, reduces the production cost and has a better social performance.②This research discovers that different mass weights are acquired from differentoriginal density of chitosan solution. However, within the range of 0.05g/50mL-　0.2g/50mL, the result measured of molecular weight is stable. Aqua density is over low if it is lower than 0.05g/50mL, and the line behavior is not good. If it is higherthan 0.2g/50mL, the trend of descent is too sharp to measure the molecular weight.③Serious pollution comes with the production of chitosan normally and the current pollution — treatment methods are not perfect. This paper provides a superior method to treat the wastewater. It costs very little to acquire the protein and calcium hydroxide, and at the same time the wastewater exhausted can be reused in craft-wash after beingtreated.④In this paper, the phenomenon of flocculating kaolinite aqua is tested. The result indicates that the higher the D.D and mass weight are, the higher the removing rate will be. In particular, when the D.D exceeds 75%, the removing result is not increasing obviously and on the other hand with the increase of D.D, the cost of preparing is higher. So the expected D.D is 75%. The influence of D.D to flocculation is more important than it is of the mass weight. Moreover, treating the Cu2+ wastewater with chitosan also acquires a good result.更多还原