锰氧八面体分子筛活化过一硫酸氢盐降解酸性橙7的研究

发布时间：2018-01-04 00:04

  本文关键词：锰氧八面体分子筛活化过一硫酸氢盐降解酸性橙7的研究　出处：《武汉纺织大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 高级氧化 锰氧八面体分子筛 酸性橙7 过硫酸氢盐 四氧化三铁

【摘要】：氧化锰八面体分子筛(OMS-2)因晶格中存在Mn~(2+)、Mn~(3+)和Mn~(4+),具有温和的表面酸性和良好的氧化还原性,成为科研工作者一个新的研究热点。基于硫酸根自由基的新型高级氧化技术作为一项绿色、经济、简单、应用广的水处理技术,但目前还存在成本高、催化剂效率较低和金属组分易流失等缺陷。因此探索OMS-2作为新型催化剂用于活化过硫酸盐降解废水具有重要意义。本论文分别利用加热回流法和无溶剂法制备了OMS-2和磁性Fe_3O_4@OMS-2催化剂,采用X射线衍射、傅里叶变换红外光谱、扫描电子显微镜、N2吸附/脱附等温线、X射线光电子能谱(XPS)和电子顺磁共振(ESR)等技术对催化剂进行表征分析来确定其结构。再以过一硫酸氢盐(PMS)为氧化剂,辅以可见光(Vis)的作用,构建了OMS-2/PMS、OMS-2/PMS/Vis和Fe_3O_4@OMS-2/PMS三种催化体系,并分别研究了这些体系降解酸性橙7(AO7)的效果、降解中间产物、动力学、催化剂稳定性以及反应机理,得出以下主要结论:(1)在OMS-2/PMS催化体系中,OMS-2和PMS对于染料废水的降解缺一不可。该体系可在15min内可完全去除AO7和其他染料。增大染料浓度、催化剂量和PMS浓度可促进染料的降解;但随着溶液p H值增大去除效率降低。五次重复后的OMS-2依然具有很好的催化性能。自由基抑制性实验证明催化剂活化PMS时产生的硫酸根自由基为该体系的主要活性物种。XPS和ESR结果表示催化机理可能涉及到在PMS中Mn(Ⅳ)离子的还原和Mn(Ⅲ)离子的氧化。基于电喷雾质谱的分析还提出了OMS-2/PMS体系降解AO7的降解途径。(2)与OMS-2/PMS体系相比,OMS/PMS/Vis体系具有更高的AO7和中间产物的降解率。ESR和XPS分析可得,OMS-2/PMS/Vis体系的催化过程涉及Mn(Ⅳ)/Mn(Ⅲ)和Mn(Ⅲ)/Mn(II)的氧化还原;而OMS-2/PMS体系仅发生在Mn(Ⅳ)和Mn(Ⅲ)之间。(3)通过无溶剂法将OMS-2负载于Fe_3O_4上生成核壳式磁性纳米催化材料具有251m2/g的高表面积和高顺磁性,同时表现出活化PMS降解有机染料的高催化活性。使用外部磁场分离反应后的催化剂后具有相当高的活性,重复使用十次去除率依然可以达到85%,是一种高效,稳定性强,回收利用率高的催化材料。
[Abstract]:Manganese oxide octahedron molecular sieve (OMS-2) has mild surface acidity and good redox properties due to the presence of Mn~(2 and Mn~(4 in the crystal lattice. New advanced oxidation technology based on sulfate radical is a green, economical, simple and widely used water treatment technology, but it still has high cost. Therefore, it is important to explore OMS-2 as a new type of catalyst for activated persulfate degradation of wastewater. In this paper, heating reflux method and solvent-free method are used respectively. OMS-2 and magnetic Fe_3O_4@OMS-2 catalysts were prepared. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N2 adsorption / desorption isotherms were used. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (ESR) were used to characterize the catalyst to determine its structure. Three catalytic systems, OMS-2 / PMS-2pPMS-Vis and Fe_3O_4@OMS-2/PMS, were constructed. The degradation effect, degradation intermediate product, kinetics, catalyst stability and reaction mechanism of these systems were studied. The main conclusions are as follows: 1) in OMS-2/PMS catalytic system. OMS-2 and PMS are indispensable for the degradation of dye wastewater. The system can completely remove AO7 and other dyes within 15 minutes and increase the dye concentration. The amount of catalyst and the concentration of PMS can promote the degradation of dyes. But with solution p, When H value was increased, the removal efficiency was decreased. After five times repeated, OMS-2 still had good catalytic performance. The experiment of free radical inhibition proved that the sulfate radical produced when the catalyst activated PMS was the main activity of the system. The results of sex species. XPS and ESR indicate that the catalytic mechanism may be related to Mn( 2) in PMS. 鈪，

本文编号：1376159