介质阻挡放电低温等离子体降解水中呋虫胺的研究

发布时间：2018-07-28 11:25

【摘要】：粮食与食品经济的稳步攀升促使了现代农业的飞速发展,为人类带来前所未有的经济利益,而与之伴随的农药经济却为自然生态环境带来巨大的负担。农药工业的生产以及成品大规模喷洒使用产生的废水和废弃物已为自然环境造成了不可磨灭的破坏,其中农药废水成为备受关注的焦点问题。呋虫胺从被发明以来在农业生产上被大规模地利用,已成为烟碱类农药家族中举足轻重的组成份子。农药废水处理问题和过去比已不可同日而语,传统处理工艺难以达到目的,因而应运而生的高级氧化技术受到专家学者们的高度青睐。本实验课题针对传统废水处理工艺难以解决的农药废水问题作出探讨,将新型烟碱类农药呋虫胺作为目标污染物,将改性后的二氧化钛光催化剂引入介质阻挡放电低温等离子体反应体系中,运用自主设计的辐流式反应装置,来探究呋虫胺废水在两类处理技术的协同作用下,不同条件对呋虫胺的影响。利用凝胶-溶胶法制备出不同掺杂比例(0%,2%,5%,10%,15%)的镧改性二氧化钛催化剂,并进行一系列的表征:通过X射线衍射分析样品晶型;扫描电子显微镜和能量色散X射线分析样品表面分布和元素存在情况;紫外可见漫反射光谱分析样品对光的反馈吸收范围并计算出带隙能量。利用各改性二氧化钛进行呋虫胺溶液的降解处理,根据处理情况并结合表征结果,筛选出最佳掺杂比例的镧改性二氧化钛催化剂。在最佳催化剂存在情况下探讨各个条件对呋虫胺降解的作用程度,例如:起始浓度、输入功率、起始pH、起始电导率、催化离子、过氧化氢和醇类抑制剂。实验结果表明:最佳的起始浓度和输入功率分别为100 mg/L和150 W;碱性环境可以很大水平上提升呋虫胺的降解程度,将pH提高至10.5时,效率可达96.8%;低电导率有利于污染物的降解处理,盐分会竞争活性自由基,抑制反应进行;Fe2+的最佳添加浓度为50mg/L,可大幅度提高降解效率(99.0%),Cu2+的催化效果不如Fe2+理想;适量添加过氧化氢能够提高处理体系环境中HO·的含量,促进反应进行;添加异丙醇可以降低呋虫胺的降解效率,与此同时也证实了HO·在反应过程中不可替代的作用。处理呋虫胺的过程属于酸化过程,溶液pH表现为逐渐降低的趋势,最后趋于稳定;溶液电导率始终处于攀升状态,这与呋虫胺的分解有关。利用高效液相色谱-质谱联用检测不同间隔呋虫胺的降解产物,根据相对分子质量以及相关参考文献推断出呋虫胺的中间产物结构,进一步推测呋虫胺在介质阻挡放电低温等离子体中的可能降解途径。实验探究结果表明,利用介质阻挡放电和改性二氧化钛结合体系处理呋虫胺废水,比单一的介质阻挡放电处理效果好,体现出一定的优点,为农药废水处理的进一步发展作出一些的借鉴意义。
[Abstract]:The steady increase of grain and food economy has promoted the rapid development of modern agriculture and brought unprecedented economic benefits to mankind, while the accompanying pesticide economy has brought a huge burden to the natural ecological environment. The production of pesticide industry and the waste water and waste produced by large-scale spraying of finished products have caused indelible damage to the natural environment, among which pesticide wastewater has become the focus of attention. Furoxime has been widely used in agricultural production since it was invented and has become an important member of the nicotine pesticide family. The problem of pesticide wastewater treatment has not been compared with the past, and the traditional treatment process is difficult to achieve the goal, so the advanced oxidation technology which came into being has been highly favored by experts and scholars. In this paper, the problem of pesticide wastewater, which is difficult to be solved by traditional wastewater treatment, is discussed, and a new type of nicotinic pesticide furoxime is used as the target pollutant. The modified titanium dioxide photocatalyst was introduced into the low temperature plasma reaction system of dielectric barrier discharge (DBD), and the self-designed radioflow flow reactor was used to explore the synergistic effect of the two kinds of treatment technologies on furoxime wastewater. Effects of different conditions on furoxime. Lanthanum modified titanium dioxide catalysts with different doping ratios (0% and 10%) were prepared by gel-sol method and characterized by a series of characterizations: X-ray diffraction (XRD) was used to analyze the crystal form of the samples; Scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) were used to analyze the surface distribution and element existence of the samples, and UV-Vis diffuse reflectance spectroscopy (DRS) was used to analyze the absorption range of the samples and to calculate the band gap energy. The modified titanium dioxide was used to degrade furoxime amine solution. According to the treatment conditions and the characterization results, the best doping ratio of lanthanum modified titanium dioxide catalyst was selected. In the presence of the best catalyst, the effects of various conditions on the degradation of furoxime were investigated, such as initial concentration, input power, initial pH, initial conductivity, catalytic ions, hydrogen peroxide and alcohol inhibitors. The experimental results show that the optimum initial concentration and input power are 100 mg/L and 150W, respectively, and the degradation of furoxime can be greatly enhanced in alkaline environment, when pH is increased to 10.5, The low conductivity is favorable to the degradation of pollutants, and the best concentration of Fe2 is 50 mg / L, which can greatly improve the degradation efficiency (99.0%). The catalytic effect of Cu2 is not as good as that of Fe2, and the best concentration of Fe2 is 50 mg 路L ~ (-1) for inhibiting the reaction, and the degradation efficiency (99.0%) of Cu2 is not as good as that of Fe2. The addition of hydrogen peroxide can increase the content of Ho and promote the reaction, and the addition of isopropanol can reduce the degradation efficiency of furoxime, which also proves that Ho plays an irreplaceable role in the reaction. The process of treatment of furosemide belongs to acidification process, the pH of the solution decreases gradually, and finally tends to stabilize, and the conductivity of the solution is always rising, which is related to the decomposition of furoxime. High performance liquid chromatography-mass spectrometry (HPLC / MS) was used to detect the degradation products of furosemide at different intervals. The structure of the intermediate product of furosemide was deduced from the relative molecular weight and related references. The possible degradation pathway of furosemide in low temperature plasma with dielectric barrier discharge (DBD) was further speculated. The experimental results show that the treatment of furoxime wastewater with dielectric barrier discharge and modified titanium dioxide is better than that of single dielectric barrier discharge. For the further development of pesticide wastewater treatment to make some reference significance.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X786

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