钼酸钴活化过一硫酸盐氧化降解有机染料的效能研究

发布时间：2018-04-23 06:55

本文选题：高级氧化技术 + 过一硫酸盐　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：近年来,随着工业的快速发展,环境污染问题日益严重,对人类的身心健康造成了极大的危害。一种基于羟基自由基的芬顿(Fenton)技术由于其较高的氧化活性,被逐渐的应用到该领域中来,但其较低的催化效率以及较窄的pH范围也制约了该技术的发展。因此,过硫酸盐作为硫酸根自由基的来源受到了广泛的关注,利用紫外光照射、过渡金属离子活化等作用,形成硫酸根自由基,进而对有机物进行降解。本课题制备了一种具有较高电化学活性的金属氧化物材料——钼酸钴,并首次将其应用于过一硫酸盐(PMS)的活化过程中,探究其催化性能以及催化氧化过程的影响因素,同时总结催化过程反应机理。本课题选用水热法制备钼酸钴前驱体粒子,并对其进行表征测试。测试结果表明材料具有均匀的微观形貌以及较高的催化活性,对前驱体进行煅烧,制得一系列金属氧化物催化剂,测试几组样品的催化活性,并选用性能最佳的一组进行后续实验。500°C煅烧后的样品结晶度较好,对应着β-CoMoO4晶型,具有较为均一的花状微观形貌,其比表面积为61.9 m2/g,较大的比表面积为样品提供了优异的催化活性。选择亚甲基蓝(MB)为目标污染物,本课题制备的CoMoO4在40 min内对MB的去除率就可达到100%,催化活性明显高于相同投加量的Co3O4以及CoFe2O4。同时,使用过后的催化剂仍具有较高的催化活性,可以循环利用。在CoMoO4/PMS体系催化氧化的过程中,PMS的初始浓度、催化剂的投入量、反应体系的温度、反应体系初始pH值对催化过程均会产生影响。同时,重碳酸盐、卤素、金属离子、天然有机物等存在也会对催化体系产生影响。这些离子的存在,主要是通过影响活性自由基的生成,或对其进行消耗从而影响体系的催化性能。在本课题探究过程中,在以地表水、自来水为背景水体的实验中,CoMoO4活化PMS的过程有一定的影响,但催化剂仍能展现出良好的降解性能。选取几种不同类型的染料对催化剂的普适性进行评估,结果表明催化剂对几种染料均具有优异降解性能,尤其对于阴离子染料,展现出很高的活性。自由基竞争动力学实验表明,硫酸根自由基和羟自由基均为CoMoO4活化PMS氧化有机物的主要活性物种,在活化PMS的过程中,电子转移过程主要发生在Co原子上,与Mo原子无关,即电子在CoMoO4表面的Co(II)上发生转移,活化PMS产生自由基,进而降解有机物。
[Abstract]:In recent years, with the rapid development of industry, the problem of environmental pollution is becoming more and more serious, which has caused great harm to the physical and mental health of human beings. A Fenton technology based on hydroxyl radical is gradually applied in this field because of its high oxidation activity, but its low catalytic efficiency and narrow pH range also restrict the development of the technology. Therefore, persulfate, as the source of sulfate radical, has been paid more and more attention. By ultraviolet irradiation and transition metal ion activation, sulfate radical is formed, and then organic matter is degraded. In this paper, a metal oxide material with high electrochemical activity, cobalt molybdate, was prepared and used for the first time in the activation process of PMSs. At the same time, the reaction mechanism of catalytic process is summarized. In this paper, cobalt molybdate precursor particles were prepared by hydrothermal method and characterized. The results showed that the materials had uniform microstructure and high catalytic activity. A series of metal oxide catalysts were prepared by calcination of the precursor, and the catalytic activity of several groups of samples was tested. The crystallinity of the samples calcined at 500 掳C was better, corresponding to the 尾 -CoMoO _ 4 crystal form, and had a more uniform flower-like micromorphology. Its specific surface area is 61.9 m2 / g, and the larger specific surface area provides excellent catalytic activity for the sample. When methylene blue (MBB) was selected as the target pollutant, the removal rate of MB by CoMoO4 was 100 in 40 min, and the catalytic activity was obviously higher than that of Co3O4 and Cofe _ 2O _ 4 with the same dosage. At the same time, after the use of the catalyst still has a higher catalytic activity, can be recycled. The initial concentration of CoMoO4/PMS, the amount of catalyst input, the temperature of the reaction system and the initial pH value of the reaction system all affect the catalytic process. At the same time, the presence of bicarbonate, halogen, metal ions and natural organic compounds will also affect the catalytic system. The existence of these ions mainly affects the catalytic performance of the system by affecting the formation of active free radicals or consuming them. In the course of this research, in the experiment of surface water and tap water as the background water, the activation of PMS by CoMoO4 has a certain effect, but the catalyst can still show good degradation performance. Several kinds of dyes were selected to evaluate the universality of the catalysts. The results showed that the catalysts had excellent degradation performance for several dyes, especially for anionic dyes. The experimental results of free radical competition kinetics show that both sulfate radical and hydroxyl radical are the main active species of PMS oxidizing organic compounds activated by CoMoO4. In the process of activating PMS, the electron transfer process mainly takes place on Co atom, which is independent of Mo atom. In other words, electrons are transferred on the surface of CoMoO4, which activates PMS to produce free radicals and then degrades organic matter.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;O643.36

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