树脂基磁性活性炭的制备及其对水源水中典型污染物的去除研究

发布时间：2019-06-11 03:50

【摘要】：近年来,随着化工、医药、农药等生产工业的迅速发展,越来越多的人工合成的有机物在生产和使用过程中进入到饮用水源水环境中。其中许多化合物对人.和动物具有细胞和遗传毒性,长期摄取可能会危害人体健康甚至导致死亡。常规的水处理工艺难以有效去除此类有机污染物,需要结合相应的深度处理工艺才能达到较好的去除效果。活性炭吸附是去除水中有机污染物的最有效技术之一,然而由于传统活性炭原料来源有限,成本较高,加之粉末活性炭的分离回收问题,限制了活性炭在水处理领域的应用。近年来,许多研究以碳含量高、来源广泛、价格低廉的工农业废弃物为原料制备活性炭,其中多种活性炭都具有较高的比表面积和显著的吸附性能,表现出良好的应用前景。离子交换树脂是一种常见的离子交换剂,应用广泛,需求量大。树脂使用饱和后可以通过酸、碱或盐溶液进行再生,由于部分杂质不易洗脱,多次使用会使其逐渐积累,导致树脂交换效能降低,出水水质难以达到处理要求。这种情况下,往往会更换新的树脂,这就导致原来的树脂被废弃。全球每年有大量的废旧树脂产生。废旧的树脂一般采用焚烧的方式进行处理,费用较高。离子交换树脂的基本组成元素为碳和氢,碳含量高;废旧树脂的价格低廉,且来源广泛。如果可以以此为原料制备活性炭,不仅可以解决废旧离子交换树脂的处理处置问题,而且还可以为活性炭制备提供一种新的原料。近年来,有研究人员开展了部分相关研究,以多种离子交换树脂为原料,采用水蒸气或二氧化碳活化法制备活性炭。然而,所得活性炭往往比表面积和孔容较低,吸附性能有限。基于上述背景,本研究以废旧的苯乙烯系离子交换树脂为原料,开展了高比表面积磁性活性炭的制备及应用研究。主要内容和结果如下:(1)以废旧的阳离子树脂为原料,通过阳离子交换负载铁,然后通过氢氧化钠高温活化法制备活性炭。分析载铁树脂的高温热解过程,研究制备条件对活性炭物理化学性质的影响。结果显示,载铁树脂的热解伴随着脱水、磺酸基脱落及树脂骨架的断裂等过程,气体产物主要有二氧化硫、二氧化碳和水。铁的添加限制了部分微孔的形成或将部分微孔堵塞,导致平均孔径增大。活化温度对活性炭的孔径分布、晶体结构以及磁性性能都具有显著的影响。活性炭的磁性性能与它的晶体结构有关。(2)以废旧阴离子树脂为原料,通过络合物阴离子交换负载铁,然后通过氢氧化钠高温活化法制备活性炭。分析载铁树脂的高温热解过程,研究制备条件对活性炭物理化学性质的影响。结果显示,树脂基团可以显著影响活性炭的制备过程及其物理化学性质。载铁阴离子树脂高温热解过程中的气体产物主要有甲胺、二甲胺、二氧化碳和水等。载铁树脂炭化后,其内部即生成了磁性铁氧化物,经过氢氧化钠高温活化,部分铁氧化物被还原,生成单质铁。铁的添加导致了活性炭比表面积的显著降低,但没有改变其孔径分布。改变活化剂用量和活化温度会影响活性炭的比表面积和孔径分布。(3)优化条件下制备的两种树脂基磁性活性炭的比表面积高达1700 m2/g以上,以此为吸附剂,用于水源水中的两种典型的有机物邻苯二甲酸二乙酯和双酚A的去除。结果显示,树脂基磁性活性炭对邻苯二甲酸二乙酯和双酚A的吸附表现出了良好的动力学性能,其过程符合准二级动力学方程,中孔的增加有利于活性炭初期吸附速率的提高。与商业活性炭相比,树脂基磁性活性炭具有更高的吸附性能。活性炭对邻苯二甲酸二乙酯和双酚A的吸附是自发放热的过程。pH值对双酚A吸附的影响是通过改变其分子形态而实现的,在实验条件下pH值对邻苯二甲酸二乙酯的吸附影响不大。溶液中存在的天然有机物尺寸越小,越易进入孔道占据位点,降低活性炭的吸附性能。吸附邻苯二甲酸二乙酯和双酚A饱和后的活性炭,可以采用氢氧化钠溶液进行再生。(4)以树脂基磁性活性炭为吸附剂,研究其对实际水源水的净化效果及毒性削减。结果显示,活性炭可有效去除水源水的DOC和UV254,净化前后水源水中有机物的分子量分布没有显著变化,自制活性炭ACS-1对类腐殖酸区的荧光物质去除效果显著。经活性炭净化后,水源水中的多种半挥发性有机物都有不同程度的去除,其中嗪草酮、敌敌畏和1-乙基-4-硝基苯三种物质去除效果显著。选取HepG2作为受试对象,进行细胞毒性及氧化损伤研究,结果显示,经活性炭净化处理后,水样的细胞毒性以及对细胞的氧化损伤等都有不同程度的减弱。
[Abstract]:In recent years, with the rapid development of the production industry, such as chemical industry, medicine and pesticide, more and more synthetic organic substances enter the drinking water source water environment in the process of production and use. In which many of the compounds are human. And the long-term ingestion can be harmful to human health and even cause death. The conventional water treatment process is difficult to effectively remove such organic pollutants, and a corresponding advanced treatment process needs to be combined to achieve better removal effect. Active carbon adsorption is one of the most effective techniques for removing organic pollutants in water. However, due to the limited source of the traditional activated carbon raw materials, the cost is high, and the separation and recovery of the powdered activated carbon have limited the application of the activated carbon in the water treatment field. In recent years, many studies have made active carbon from industrial and agricultural wastes with high carbon content, wide source and low price. Ion exchange resin is a kind of common ion exchanger, and has wide application and large demand. After the resin is saturated, the resin can be regenerated by an acid, a base or a salt solution, and because some impurities are not easy to be eluted, the resin is gradually accumulated in a plurality of times, so that the resin exchange efficiency is reduced, and the water quality of the effluent is difficult to reach the processing requirement. In this case, a new resin is often replaced, which causes the original resin to be discarded. The world has a large number of waste resins every year. The waste resin is generally treated by incineration, and the cost is higher. The basic components of the ion exchange resin are carbon and hydrogen, the carbon content is high, the price of the waste resin is low, and the source is wide. If that active carbon can be prepare as a raw material, not only the treatment and treatment problem of the waste ion exchange resin can be solved, but also a new raw material can be provided for the preparation of the active carbon. In recent years, some relevant research has been carried out by researchers, and the active carbon is prepared by using a variety of ion-exchange resins as raw materials and by using water vapor or carbon dioxide activation method. However, the activated carbon is often lower in surface area and pore volume and limited in adsorption performance. Based on the above background, the preparation and application of high specific surface area magnetic activated carbon were carried out by using the waste styrene-based ion-exchange resin as the raw material. The main contents and results are as follows: (1) The waste-used cationic resin is used as the raw material, and the loaded iron is exchanged through the cation, and then activated carbon is prepared by the high-temperature activation method of sodium hydroxide. The effects of preparation conditions on the physical and chemical properties of activated carbon were studied. The results show that the pyrolysis of the iron-carrying resin is accompanied by the process of dehydration, the shedding of the sulfonic acid group and the fracture of the resin skeleton, and the gas product mainly contains sulfur dioxide, carbon dioxide and water. The addition of iron limits the formation of some of the pores or the plugging of a portion of the pores, resulting in an increase in the average pore size. The activation temperature has a significant effect on the pore size distribution, crystal structure and magnetic properties of the activated carbon. The magnetic properties of activated carbon are related to its crystal structure. (2) the waste anion resin is used as a raw material, the loaded iron is exchanged through a complex anion, and then activated carbon is prepared by a sodium hydroxide high-temperature activation method. The effects of preparation conditions on the physical and chemical properties of activated carbon were studied. The results show that the resin group can significantly influence the preparation process and the physical and chemical properties of the activated carbon. The gas products in the high-temperature pyrolysis of the iron-carrying anion resin are mainly methylamine, dimethylamine, carbon dioxide and water. After the iron-carrying resin is carbonized, a magnetic iron oxide is generated inside the iron-carrying resin, the iron oxide is activated at high temperature through the sodium hydroxide, and a part of the iron oxide is reduced to generate the elementary iron. The addition of iron results in a significant reduction in the specific surface area of the activated carbon, but does not change its pore size distribution. Changing the amount of the activator and the activation temperature will affect the specific surface area and pore size distribution of the activated carbon. And (3) the specific surface area of the two kinds of resin-based magnetic activated carbon prepared under the optimized condition is as high as 1700 m2/ g or more, thus the adsorbent is used for the removal of two typical organic matter phthalate and bisphenol A in the water source water. The results show that the adsorption of diethyl phthalate and bisphenol A by the resin-based magnetic activated carbon shows good dynamic performance, and the process is in accordance with the quasi-second-order kinetic equation, and the increase of the mesopore is favorable to the increase of the initial adsorption rate of the activated carbon. Compared with commercial activated carbon, the resin-based magnetic activated carbon has higher adsorption performance. The adsorption of diethyl phthalate and bisphenol A by activated carbon is a spontaneous exothermic process. The effect of pH on the adsorption of bisphenol A was achieved by changing its molecular morphology, and the pH value in the experimental conditions had little effect on the adsorption of diethyl phthalate. The smaller the size of the natural organic matter present in the solution, the more easily enter the pore-occupied site and lower the adsorption property of the activated carbon. The adsorption of diethyl phthalate and the activated carbon after the bisphenol A is saturated can be carried out by adopting a sodium hydroxide solution. And (4) using the resin-based magnetic activated carbon as an adsorbent to study the purification effect and the toxicity reduction of the water in the actual water source. The results show that the active carbon can effectively remove the DOC and the UV254 of the water, and the molecular weight distribution of the organic matter in the water source water before and after purification is not changed significantly, and the self-made active carbon ACS-1 has a significant effect on the removal of the fluorescent substance in the humic acid region. After the purification of activated carbon, the various semi-volatile organic compounds in the water source water have different degree of removal, among which, the removal effect of the three substances of the trione, the dichlorvos and the 1-ethyl-4-nitrophenol is significant. HepG2 was selected as the subject to study the cytotoxicity and oxidative damage. The results showed that the cytotoxicity of the water sample and the oxidative damage to the cells were reduced after the treatment with activated carbon.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU991.2;TQ424.1

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