碳基纳米复合材料的制备及其催化降解有机污染物的研究

发布时间：2018-06-27 16:45

本文选题：多相催化剂 + 水热法　；参考：《浙江大学》2015年博士论文

【摘要】：在资源紧张,水环境日益恶化的今天,如何更快、更高效地进行污水处理是一个亟待解决的重大问题。因此,近年来新型多相催化剂的合成及其性能研究成为学者们关注的热点。本论文以椰壳活性炭、剩余污泥和蓝绿藻类为研究对象,对其进行预处理后作为载体,通过水热法或高温煅烧法,制备多相催化剂,用于降解有机污染物,既做到了废弃物的资源化利用,又实现了“以废治废”的目的。主要结论如下：(1)利用水热法制备纳米MnOx@椰壳活性炭,研究了纳米MnOx@椰壳活性炭氧化降解有机污染物的性能。与高温煅烧法制备的MnoX@椰壳活性炭相比,水热法制备的纳米MnOx@椰壳活性炭表现出了更高的氧化性能。研究发现,纳米MnOx@椰壳活性炭中MnOx主要以Mn4+和Mn3+形式存在,这种多价态的锰氧化物提高了纳米MnOx@椰壳活性炭的氧化降解能力。除了酸性红73之外,纳米MnOx@椰壳活性炭对其它九种阴离子染料也表现出较好的降解效果,其降解效率均大于90%。循环利用实验证明,纳米MnOx@椰壳活性炭具有较高的稳定性能,但在酸性条件下,反应体系有少量锰的溶出。GC-MS分析结果表明,大部分中间产物都是生物可降解的小分子有机酸。(2)鉴于污泥含水量高且难脱水,通过水热法实现湿污泥处理与MnO,催化剂制备同步,获得MnOx/HCAS催化剂,研究表明MnOx/HCAS在中性条件下能够活化过硫酸盐产生SO4-·,在此基础上考察了该体系对多种阴离子染料的氧化降解性能。实验发现,在MnOx/HCAS投加量为1.0 g/L,过硫酸盐浓度为1.0 g/L的中性条件下,MnOx/HCAS-Oxone体系在30 min内对50 mg/L染料的降解效率达到98%,COD去除率约为45%。醇淬灭试验证实了在MnOx/HCAS-Oxone体系中对染料氧化降解起主导作用的自由基为SO4-·。MnOx/HCAS能够多次循环使用,对反应前后MnOx/HCAS表面Mn结合能的分析发现催化剂表面Mn4+和Mn3+参与过硫酸盐的活化。反应前后及反应后上清液重金属的溶出量极小,表明污泥中的重金属能够被固定在MnOx/HCAS催化剂中,从而避免对环境造成危害。基于污泥的多样性,制备了不同类型的污泥负载MnOx催化剂,它们均对染料表现出良好的降解效果,效率达到98%以上,表明MnOx/HCAS催化剂的制备不受污泥种类的干扰,也说明MnOx/HCAS催化剂更具有实际意义。(3)基于蓝绿藻水华频繁爆发及其打捞效率低的问题,通过简单、高效的方法收集并资源化利用藻类,通过低温聚合、高温煅烧的方法制备了更高活性的多相类芬顿催化剂FeNi-N/Al2O3/C中空微球,考察了该体系对有机污染物的催化降解效果、降解过程和机理。研究发现,FeNi-N/Al2O3/C中空微球在偏中性条件下也表现出良好的催化活性。当FeNi-N/Al2O3/C中空微球投加量为0.4 g/L, H2O2浓度为40 mM时,反应30 min内对50 mg/L染料和30 mg/L苯酚的降解效率均达到了95%,TOC去除率分别达到了69.9%和76.0%,H2O2利用率分别为65.7%和67.6%。经过十二次循环利用后,FeNi-N/Al2O3/C中空微球对染料和苯酚的降解效率仍然保持在95%,反应后上清液中Fe、Ni和Al的溶出量极少,而且反应前后FeNi-N/Al2O3/C中空微球在外貌和形态上基本不变,体现了FeNi-N/Al2O3/C中空微球的高稳定性能。在催化降解过程中,FeNi-N/Al2O3/C中空微球中部分Fe3+转化为Fe2+, Ni和Al的价态不变。在原位拉曼光谱和电子顺磁共振波谱等分析的基础上,揭示了FeNi-N/Al2O3/C中空微球催化剂/H2O2固液界面电子转移调控与有机污染物去除的机理,即在催化剂表面酸性微环境下,通过Fe(Ⅲ)和Fe(Ⅱ)之间的电子转移,实现H202活化产生HO·,进而降解和矿化有机污染物。
[Abstract]:Nowadays, with the shortage of resources and the worsening water environment, it is an important problem to be solved faster and more efficiently. Therefore, in recent years, the research of the synthesis and performance of the new multiphase catalyst has become a hot spot of concern. After pretreatment, the polyphase catalyst was prepared by hydrothermal method or high temperature calcination, which can be used to degrade organic pollutants, not only do the utilization of waste, but also achieve the purpose of "waste treatment by waste". The main conclusions are as follows: (1) nano MnOx@ coconut shell activated carbon was prepared by hydrothermal method, and the activity of nano MnOx@ coconut shell was studied. Compared with the MnoX@ coconut shell activated carbon prepared by high temperature calcining method, the nano MnOx@ coconut shell activated carbon prepared by hydrothermal method showed higher oxidation performance. It was found that the MnOx of nano MnOx@ coconut shell activated carbon existed mainly in the form of Mn4+ and Mn3+, and this multivalent manganese oxide enhanced the nanometer MnO. The oxidation degradation ability of x@ coconut shell activated carbon. Besides acid red 73, nano MnOx@ coconut shell activated carbon also showed good degradation effect on other nine kinds of anionic dyes. The degradation efficiency was higher than that of 90%. recycling experiment. The nano MnOx@ coconut shell activated carbon had high stability performance, but under the acid condition, the reaction system was in the acid condition. The results of.GC-MS analysis of a small amount of manganese showed that most of the intermediate products were biodegradable small molecular organic acids. (2) in view of the high water content and difficult dehydration of the sludge, the wet sludge treatment was synchronized with the preparation of MnO, and the MnOx/HCAS catalyst was obtained by hydrothermal method. The research showed that MnOx/HCAS could activate sulfuric acid under neutral conditions. Salt produced SO4-. On this basis, the oxidation degradation performance of the system for various anionic dyes was investigated. It was found that the degradation efficiency of MnOx/HCAS-Oxone system to 50 mg/L dyes in 30 min was 98% and COD removal rate was about 45%. alcohol quenching test under the neutral condition of MnOx/HCAS dosage of 1 g/L and the concentration of persulfate at 1 g/L. It is confirmed that the free radical which plays a leading role in the oxidation and degradation of dyes in the MnOx/HCAS-Oxone system can be used repeatedly for SO4-..MnOx/HCAS. The analysis of Mn binding energy on the surface of MnOx/HCAS before and after the reaction shows that Mn4+ and Mn3+ on the surface of the catalyst are involved in the activation of persulfate. The dissolution of heavy metals in the supernatant is very small before and after the reaction. It shows that heavy metals in the sludge can be immobilized in the MnOx/HCAS catalyst to avoid the harm to the environment. Based on the diversity of sludge, different types of sludge loaded MnOx catalysts have been prepared, both of which show good degradation effect to the dye, and the efficiency is above 98%, indicating that the preparation of MnOx/HCAS catalyst is not subject to the type of sludge. The MnOx/HCAS catalyst is of more practical significance. (3) based on the frequent eruption of cyanobacteria bloom and the low fishing efficiency, the high active FeNi-N/Al2O3/C hollow microspheres are prepared by a simple and efficient method of collecting and utilizing algae, and using the method of low temperature polymerization and high temperature calcination. The catalytic degradation of organic pollutants, the degradation process and the mechanism of the system were investigated. It was found that FeNi-N/Al2O3/C hollow microspheres also showed good catalytic activity under partial neutral conditions. When the dosage of FeNi-N/Al2O3/C hollow microspheres was 0.4 g/L and the concentration of H2O2 was 40 mM, 50 mg/L dyes and 30 mg/L phenol were reacted to 30 min. The degradation efficiency reached 95%, the removal rate of TOC reached 69.9% and 76% respectively. The utilization rate of H2O2 was 65.7% and 67.6%. after twelve cycles respectively. The degradation efficiency of FeNi-N/Al2O3/C hollow microspheres for dye and phenol remained at 95%. The dissolution of Fe, Ni and Al in the supernatant was very little after reaction, and the FeNi-N/Al2O3/C in FeNi-N/Al2O3/C before and after reaction. The empty microspheres are basically unchanged in appearance and morphology, reflecting the high stability of FeNi-N/Al2O3/C hollow microspheres. In the process of catalytic degradation, partial Fe3+ in FeNi-N/Al2O3/C hollow microspheres is converted to Fe2+, and the valence state of Ni and Al is unchanged. On the basis of in situ Raman spectroscopy and electron paramagnetic resonance spectroscopy, the FeNi-N/Al2O3/C hollow is revealed. The mechanism of electron transfer regulation and removal of organic pollutants at the solid liquid interface of the microsphere catalyst /H2O2, that is, through the electron transfer between Fe (III) and Fe (II) in the acid microenvironment of the catalyst surface, the H202 activation produces HO, and then degradates and mineralized organic pollutants.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：X703;TB33

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