壳聚糖的制备及其在给水处理中的絮凝性能研究

发布时间：2018-06-25 06:59

  本文选题：壳聚糖 + 制备　； 参考：《武汉理工大学》2013年硕士论文

【摘要】：本课题选取虾壳为原料制备壳聚糖(CS),探究了氢氧化钠浓度、壳聚糖与氢氧化钠溶液质量比、pH值、反应温度和时间对CS脱乙酰度的影响以及过氧化氢浓度在其降解过程中对CS分子量的影响；探究了絮凝过程中CS分子量、脱乙酰度、投加量,pH值,搅拌速度和时间分别与有机物、浊度、COD、残余铝的去除关系。由于工业的高速发展使得我国大部分河流湖泊中有机污染物的种类和数量增多,常规的絮凝处理无法完全去除这些污染物,并且会导致二次污染,而CS在水处理中因天然无毒成为研究热点,通过与无机絮凝剂复合使用,考察了其在给水处理中的絮凝效果,其效果较传统絮凝剂更加环保、高效且价格低廉。 以潜江虾壳为原料,用3.75%的盐酸去除钙质,4.5%氢氧化钠脱蛋白,即可制备甲壳素。通过甲壳素制备高脱乙酰度壳聚糖的反应条件为：48%的氢氧化钠溶液,料碱比为1：9,反应温度90℃,反应时间2.5h,实验表明壳聚糖脱乙酰度可以达到85.3%,壳聚糖分子量为6.23×105。通过红外光谱和X-射线衍射等对壳聚糖样品进行表征并初步分析了其结构和降解机理。 考察了壳聚糖对水中有机物的吸附效能,结果表明：当壳聚糖脱乙酰度在78～85%、分子量为5.83×104左右,pH值为6.0～6.5时,壳聚糖对COD的去除率较高。根据无机、有机、无机-有机复合原理,对PAC、CF-PAC、CS以及PAC/CS、 CF-PAC/CS对模拟地表水进行絮凝实验,结果表明：CF-PAC (20.0ppm)在CS(0.10ppm)助凝作用下,快搅速度300r/min(60s),'曼搅速度60r/min(10min),出水浊度可以达到0.4NTU以下,铝离子的含量仅为0.041mg/L,较传统的PAC低76.02%,较PAC/PAM低70.07%,使得饮用水更加的健康,且吨处理费用较传统絮凝剂PAC略低。 对复合絮凝剂的机理做了简要的探析。复合絮凝剂中CF-PAC组分在水中先水解后聚合,其中铁离子先快速的水解,随后铝离子水解,水解后铁离子和铝离子形成的多核羟基呈现正电性,可以迅速和水中负电胶体微粒吸附结合。CS水解后分子链上的氨基和羟基质子化而带上正电荷,进一步加大了絮凝的电中和作用,同时其长分子链迅速的连接相邻微粒形成架桥作用。CF-PAC与CS的复合絮凝使得电中和作用、架桥、网捕卷扫协同作用,缩短了絮凝沉降时间,提高了絮凝效果。
[Abstract]:In this paper, chitosan (CS) was prepared from shrimp shell. The concentration of sodium hydroxide and the mass ratio of chitosan to sodium hydroxide solution were studied. The effect of reaction temperature and time on CS deacetylation degree and the effect of hydrogen peroxide concentration on CS molecular weight in the process of degradation were studied. Stirring speed and time are related to the removal of organic matter, turbidity, COD and residual aluminum, respectively. Due to the rapid development of industry, the species and quantity of organic pollutants in most rivers and lakes in our country increase, and the conventional flocculation treatment can not completely remove these pollutants, and will lead to secondary pollution. CS has become a research hotspot in water treatment because of its natural non-toxicity. The flocculation effect of CS in water treatment was investigated by using inorganic flocculant. Compared with traditional flocculant, CS was more environmentally friendly, efficient and cheap. Chitin was prepared from Qianjiang shrimp shell with 3.75% hydrochloric acid removing 4.5% sodium hydroxide deproteinization. The reaction conditions of chitosan with high degree of deacetylation from chitin were as follows: 1: 48% sodium hydroxide solution, 1: 9 ratio of material to alkali, 90 鈩，

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