磷酸银基复合材料光催化降解水中阿特拉津的研究
发布时间:2018-03-04 11:49
本文选题:磷酸银基复合催化剂 切入点:阿特拉津 出处:《华中农业大学》2017年硕士论文 论文类型:学位论文
【摘要】:阿特拉津(Atrazine)作为一种在世界范围内广泛使用的除草剂,能够有效防治农田杂草生长以提高农业生产效益,但是残留的阿特拉津能进入土壤、河流、湖泊,对地下水、地表水造成污染,并随着生物链的富集,对植物、动物、人类造成不同程度的危害。近年来,随着光催化技术的不断发展,简单、廉价、高效地光催化降解阿特拉津成为人们研究的热点。Ag_3PO_4作为一种新型高活性可见光催化剂,已在光解制氧、还原CO_2、降解NO_x化合物、降解有机污染物等方面开展了广泛研究,但对其光催化降解阿特拉津的研究较少。本文利用不同改性方法制备了磷酸银基复合催化剂(Au NRs/Ag_3PO_4、Mo-Ag_3PO_4)。通过SEM、XRD、XPS等一系列手段进行表征,检测了其物理和化学结构性质。研究了可见光照射下,磷酸银基复合催化剂(Au NRs/Ag_3PO_4、Mo-Ag_3PO_4)光催化降解水中阿特拉津的降解效果。磷酸银基复合催化剂光催化降解阿特拉津的研究表明,当反应体系初始pH=6时,其光催化活性最好,并且随着光催化过程的进行,体系的pH值逐渐降低。通过自由基捕获实验发现,催化反应过程中主要的活性物种为h~+和·OH自由基。利用高效液相色谱-质谱(LC-MS)、离子色谱(IC)测定了复合催化剂光催化降解阿特拉津的中间产物:2-羟基-4-乙胺基-6-异丙胺基-1,3,5-三嗪、2-氯-4-氨基-6-异丙胺基-1,3,5-三嗪、2-羟基-4-氨基-6-异丙胺基-1,3,5-三嗪、2,4-二羟基-6-异丙胺基-1,3,5-三嗪等,并推测出磷酸银基复合催化剂催化降解阿特拉津的可能机理:在可见光的照射下,Ag_3PO_4受光激发产生光生e~-与h~+,复合体系中Au NRs以及Mo元素的存在有利于促进e~-的转移,提高催化活性;光生h+则与反应体系中的H2O反应生成·OH和H~+,使体系的pH值随着反应的进行而降低;与此同时,产生的·OH自由基分别进攻阿特拉津分子的C-Cl键、侧链乙胺基仲碳原子及侧链异丙胺基中心碳原子,经脱氯-羟基化和脱烷基作用等一系列的化学反应,得到最后的产物为三聚氰酸,三聚氰酸会被进一步矿化成H_2O、CO_2、NO_3~-。本论文不仅丰富了磷酸银基复合催化剂在光催化降解农药有机污染领域的应用,而且为光催化降解阿特拉津的实际应用提供了理论基础。
[Abstract]:Atrazine (Atrazine), a herbicide that is widely used around the world, can effectively control the growth of weeds in farmland to improve agricultural productivity, but the residual atrazine can enter the soil, rivers, lakes, and groundwater. Surface water causes pollution, and with the enrichment of biological chain, it causes varying degrees of harm to plants, animals and human beings. In recent years, with the continuous development of photocatalytic technology, simple, cheap, High efficient photocatalytic degradation of atrazine has become a hot topic. Ag3PO4, as a new type of highly active visible light catalyst, has been widely studied in photodegradation of oxygen, reduction of CO _ 2, degradation of NO_x compounds, degradation of organic pollutants, and so on. However, the photocatalytic degradation of atrazine was seldom studied. In this paper, silver phosphate-based composite catalyst au NRsr / AgS / AW / AW / APS / AW / AW / Ag / 3PO4 / M were prepared and characterized by a series of methods, such as SEM- XRD- XPS, Mo-AgSP, 3PO4, and so on. The physical and chemical properties of Atrazine were investigated. The photocatalytic degradation of atrazine in water was studied by using silver phosphate based composite catalyst au NRs / Ag3PO4 / Snap4Mo-Ag3PO4 under visible light irradiation. The photocatalytic degradation of atrazine by silver phosphate-based composite catalyst was studied. When the initial pH of the reaction system was 6:00, the photocatalytic activity of the system was the best, and the pH value of the system gradually decreased with the process of photocatalysis. H ~ and 路OH radicals were the main active species in the catalytic reaction. The intermediate product of atrazine was determined by high performance liquid chromatography-mass spectrometry (HPLC-MS) and ion chromatography (ICIC). 2-chloro-4-amino-6-isopropylamino-2-hydroxy-4-amino-6-isopropylamino-2-hydroxy-4-amino-6-isopropylaminyl -1-triazine, 2-hydroxy-4-amino-6-isopropylamino-2-triazine, 5-triazino-5-triazino-2-dihydroxy-6-isopropylamine, etc., The possible mechanism of the degradation of atrazine by silver phosphate based composite catalyst was inferred: Ag3PO4 was stimulated by visible light to produce photogenerated edo- and h-, and the presence of au NRs and Mo in the composite system was helpful to promote the transfer of ego-. The photogenerated h reacts with H 2O in the reaction system to form 路OH and H ~, which makes the pH value of the system decrease with the reaction. At the same time, the generated 路OH free radicals attack the C-Cl bond of atrazine molecule respectively. After a series of chemical reactions, such as dechlorination, hydroxylation and dealkylation, the final product of the secondary carbon atom and the central carbon atom of isopropylamine group in the side chain was obtained by a series of chemical reactions such as dechlorination, hydroxylation and dealkylation. Tripolycyanoic acid will be further mineralized to form S / C _ 2O _ 2 CO _ 2O _ 3C _ 3. This paper not only enriches the application of silver phosphate based composite catalyst in the field of photocatalytic degradation of pesticide organic pollution, but also provides a theoretical basis for the practical application of photocatalytic degradation of atrazine.
【学位授予单位】:华中农业大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:X592;O643.36;O644.1
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