纳米零价铁处理水中含氯有机物和铅的研究

发布时间：2019-05-24 23:10

【摘要】：随着社会生产的飞速发展,地下水资源受到了城市垃圾、工业三废、农业生产、采矿冶炼等多种因素的污染。我国是一个干旱缺水严重的国家,地下水占我国水资源总量的31%左右,因此如何做好地下水资源污染整治工作受到了社会的广泛关注。自上世纪90年代末,纳米零价铁由于其减少地下污染物如多氯联苯、氯化溶剂和重金属的潜力被研究用于地下水修复。纳米零价铁由于其高活性在环境方面显示出巨大的前景,并进行了大量的实验室和现场研究来评估其有效性。但是,纳米零价铁裸露在空气当中容易发生自燃,即使与空气缓慢接触也容易发生氧化,使表面生成氧化物或氢氧化物而降低反应活性,这些问题都影响着纳米零价铁在实际中的应用。针对以上问题,本研究以对环境友好的高岭土(Kaolin)、膨润土(Bentonite)、沸石(Zeolite)、羧甲基纤维素钠(CMC)、琼脂(Agar)和淀粉(Starch)为包裹剂制备了包裹型纳米零价铁材料及紫叶小檗树叶提取液绿色合成了纳米零价铁,并通过X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅立叶红外光谱仪(FTIR)等对所制得的样品进行表征;考察了其对三氯甲烷(Trichloromethane,TCM)、四氯化碳(Carbon Tetrachloride,CTC)及混合废水Pb~(2+)-TCM的还原去除能力。论文的主要研究结论有:1.以环境友好型的Kaolin、Bentonite和Zeolite为表面修饰材料,制备矿物包裹型纳米零价铁。矿物包裹型纳米零价铁去除三氯甲烷(TCM)的批实验结果表明:影响TCM去除效果的主要因素有矿物包裹型纳米零价铁的用量,TCM的初始浓度和p H值。初始浓度较低,矿物包裹型纳米零价铁的用量较大时有利于TCM的去除。在模拟TCM浓度为10mg/L,Kaolin-n ZVI、Bentonite-n ZVI和Zeolite-n ZVI的投加量为1.5g/L,p H为5,反应2h脱氯效果较好,TCM的脱氯率分别为73.1%、70.9%和74.4%。2.以廉价环保的Agar、CMC和Starch为表面修饰剂,制备包裹型纳米零价铁。包裹型纳米零价铁去除三氯甲烷(TCM)的柱实验结果表明:影响TCM去除效果的主要因素有Agar-n ZVI、CMC-n ZVI、Starch-n ZVI的投加量、TCM初始浓度和水的流量。在投加量充足的情况下,TCM去除效率不受废水浓度影响。在模拟TCM废水浓度为0.1mg/L,Agar-n ZVI、CMC-n ZVI、Starch-n ZVI、n ZVI投加量为0.04g/L,流量为5m L/min,反应1h时靠近出水口的取样口去除效果最好,去除率分别为99.21%、98.13%和97.6%。包裹型纳米零价铁还原降解TCM的体系符合准一级反应动力学,反应速率随着TCM初始浓度的升高而降低的幅度较大,随着包裹型纳米零价铁的投加量增加而升高的幅度较小。3.CMC包裹纳米零价铁降解三氯甲烷(TCM)和铅的正交实验的主要影响因素有:CMC包裹型纳米零价铁的用量、TCM和铅的初始浓度、反应时间和初始p H值。实验结果表明:较高的CMC包裹纳米零价铁的投加量和较低的初始TCM和铅浓度有利于降解还原效果;在TCM浓度为0.4mg/L,Pb~(2+)浓度为40mg/L,p H值为5.0,CMC-n ZVI投加量分别为1mg/L,反应3h去除效果较好,TCM和Pb~(2+)去除率分别为96.5%和92.0%,总去除率为94.3%。4.紫叶小檗树叶提取液绿色合成的纳米零价铁处理TCM实验的主要影响因素有:TCM初始浓度、p H值和初始p H值。实验结果表明:紫叶小檗树叶提取液制备的纳米零价铁具有较好的分散性,平均粒径约为20-50nm。绿色合成的纳米零价铁对水中CTC的具有较好的去除效果。影响绿色合成的纳米零价铁对CTC去除效果的影响因素有CTC初始浓度,p H值,和绿色合成纳米零价铁的投加量。当CTC初始浓度为4mg/L,p H值为6.0,绿色合成纳米零价铁投加量为0.14g/L,反应90min时,去除效果较好,CTC去除率为99.8%。
[Abstract]:With the rapid development of social production, the groundwater resources have been polluted by various factors such as urban waste, industrial three wastes, agricultural production, mining and smelting. China is a country with severe drought and water shortage, with the groundwater accounting for about 31% of the total water resources in China, so how to do well the groundwater resource pollution control work has been widely concerned by the society. Since the late 1990s, the potential of nano-zero-valent iron as a result of its reduction of underground pollutants, such as polychlorinated biphenyls, chlorinated solvents and heavy metals, has been studied for groundwater remediation. The nano-zero-valent iron has a great prospect in the environment due to its high activity, and has carried out a large number of laboratory and field studies to evaluate its effectiveness. However, the nano-zero-valent iron is easy to spontaneous combustion in the air, and the oxidation is easy to occur even when the nano zero-valent iron is in slow contact with the air, so that the oxide or the hydroxide is generated on the surface to reduce the reaction activity, and the problems all influence the application of the nano zero-valent iron in the practical application. In view of the above problems, the present study is based on environmentally friendly kaolin (Kaolin), bentonite (Bentonite), zeolite (Zeolite), sodium methylcellulose (CMC), The nano-zero-valent iron was synthesized with agar (Agar) and starch (Starch) as the wrapping agent, and the nano-zero-valent iron was synthesized by the green synthesis of the extract of the leaves of the leaves of the leaves of the purple leaf, and the nano-zero-valent iron was prepared by the X-ray powder diffractometer (XRD), the scanning electron microscope (SEM) and the transmission electron microscope (TEM). The obtained samples were characterized by Fourier transform infrared (FTIR) and the like. The reduction and removal ability of the Pb ~ (2 +)-TCM for trichloromethane (TCM), carbon tetrachloride (carbon tetrachloride (CTC) and mixed wastewater Pb ~ (2 +)-TCM was investigated. The main conclusions are as follows:1. The mineral-coated nano-zero-valent iron was prepared by using the environment-friendly Kaolin, Bennite and Zeolite as surface-modified materials. The experimental results of the removal of chloroform (TCM) from the mineral-coated nano-zero-valent iron show that the main factors that affect the removal effect of the TCM include the amount of the mineral-coated nano-zero-valent iron, the initial concentration of the TCM and the p-H value. The initial concentration is low, and the consumption of the mineral-coated nano zero-valent iron is large, and is beneficial to the removal of the TCM. When the concentration of the simulated TCM was 10 mg/ L, the dosage of Kaolin-n ZVI, Bennite-n ZVI and Zeolite-n ZVI was 1.5 g/ L, the p H was 5, the dechlorination of the reaction was good, and the dechlorination rate of the TCM was 73.1%, 70.9% and 74.4%, respectively. The coated nano-valent iron was prepared by using the cheap and environment-friendly Agar, CMC and Starch as the surface modifier. The results show that the main factors that affect the removal effect of TCM include Agar-n ZVI, CMC-n ZVI, the addition of search-n ZVI, the initial concentration of TCM and the flow of water. The removal efficiency of the TCM is not affected by the concentration of the waste water when the dosage is sufficient. At the simulated TCM wastewater concentration of 0.1 mg/ L, Agar-n ZVI, CMC-n ZVI, Starch-n ZVI, n ZVI dosage of 0.04 g/ L and flow rate of 5 m L/ min, the removal effect of the sampling port close to the water outlet at 1 h is the best, and the removal rate is 99.21%, 98.13% and 97.6%, respectively. The system of the coated nano-zero-valent iron reduction and degradation TCM meets the quasi-primary reaction kinetics, and the reaction rate decreases with the increase of the initial concentration of the TCM, The main influencing factors of CMC-coated nano-zero-valent iron degradation of trichloromethane (TCM) and lead were: the dosage of CMC-coated nano-zero-valent iron, the initial concentration of TCM and lead, the reaction time and the initial p-H value. The results show that the dosage of the higher CMC-coated nano-zero-valent iron and the low initial TCM and lead concentration are beneficial to the degradation reduction. The concentration of the TCM is 0.4 mg/ L, the concentration of Pb ~ (2 +) is 40 mg/ L, the p H value is 5.0, the dosage of CMC-n ZVI is 1 mg/ L, and the effect of the reaction is better. The removal rate of TCM and Pb ~ (2 +) was 96.5% and 92.0%, and the total removal rate was 94.3%. The main influencing factors of the green synthesis of the green-synthesized nano-zero-valent iron in the extraction of the leaves of the leaves of the leaves of the purple leaves include the initial concentration of the TCM, the p-H value and the initial p-H value. The results of the experiment show that the nano-zero-valent iron prepared by the extract of the leaves of the leaf of the leaves of the purple leaves has good dispersibility, and the average particle size is about 20-50 nm. The green-synthesized nano-zero-valent iron has better effect of removing CTC in water. The effect of green-synthesized nano-zero-valent iron on CTC removal efficiency is the initial concentration of CTC, the value of p H, and the dosage of green synthetic nanometer zero-valent iron. When the initial concentration of CTC is 4 mg/ L, the value of p H is 6.0, the dosage of green synthetic nanometer zero-valent iron is 0.14 g/ L, the removal effect is better when the reaction is 90 min, and the removal rate of CTC is 99.8%.
【学位授予单位】：景德镇陶瓷大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X523

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