纳米锰氧化物制备及催化氧化水中有机污染物的研究
文献类型：学位论文
| 作者 | 屠锦军
|
| 学位类别 | 博士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 胡春 |
| 关键词 | 多价态 生物锰氧化物 化学锰氧化物 锰氧化菌 锰氧化物分子筛 mixed valence biologically produced manganese oxides chemically produced manganese oxides Mn-oxidizing bacteria manganese oxides molecular sieves |
| 其他题名 | Preparation and catalytic oxidation of organic pollutants in water by nano-manganese oxides |
| 学位专业 | 环境工程 |
| 中文摘要 | 水体微污染有机物对水生态和人类健康形成威胁，已引起关注，为解决这些难降解的微污染有机物，本论文分别采用微生物与化学方法制备了多价态生物锰氧化物（BioMnOx）和化学锰氧化物（MnOx）两类纳米材料，选用医药类和氯酚类化合物作为目标污染物，考察锰氧化物结构性能与反应活性之间的关系，深入研究其氧化反应机理，并进一步探讨了纳米材料表面自活化氧系统构建。主要 研究内容和结果如下： （1）BioMnOx 制备及反应活性 利用锰氧化菌Pseudomonas sp. G7 氧化Mn(II)合成一系列BioMnOx，其中含有Mn(II)，Mn(III)和Mn(IV)三个价态的BioMnOx(0.4)-7 对医药类污染物和天然腐植酸显示很高的降解活性，实验的污染物都被转化为小分子酸，而且反应过程中几乎没有Mn(II)释放，催化剂具有长期高效稳定性。同时，建立了BioMnOx负载的氧化铝小球固定床反应器，证实该系统具有很高的净化能力。 （2）BioMnOx 降解有机污染物机制 BioMnOx 中Mn(II)，Mn(III)和Mn(IV)三个价态共存加快催化剂-水固微界面电子转移，使催化剂表面还原态的Mn(II)和Mn(III)与水溶液中的O2 作用产生超氧自由基（O2•-）。同时，Mn(IV)和O2•-的协同氧化导致有机污染物高效降解，保证多价态Mn 之间的电子循环，抑制Mn(II)释放。 （3）MnOx 合成及反应活性 制备了α，β，γ，δ 和λ 五种不同晶型的MnO2，其中δ-MnO2 显示最高的氧化活性，在中性条件下，对环丙沙星（CIP）去除率可以达到88%。在研究其去除2-CP 的反应机理中发现，2-CP 只发生脱氯反应，而没有发生苯环开环反应，说明δ-MnO2 的主要氧化能力来源于自身的Mn(IV)，空气中的O2 不能在δ-MnO2表面活化形成O2•-。 （4）Ce 掺杂锰氧化物分子筛结构特征及氧化有机污染物机制 制备了一系列Ce 孔道掺杂的多价态锰氧化物分子筛（Ce-OMS-2），Ce 的掺杂明显增加了该分子筛的比表面积，表面氧缺陷和表面吸附的氧分子。研究结果证实，在Ce-OMS-2 的水固微界面上，还原态的Mn(II)和Mn(III)与表面吸附的氧分子反应生成O2•-，且还原态Mn 转化为Mn(IV)。这两种氧化物种协同氧化CIP 产生3-丁烯酰胺和丙酰胺等中间产物及另外一些小分子酸，并抑制Mn(II)释放。Ce-OMS-2 催化剂-水固微界面上的电子转移，使催化剂保持长期活性和稳定性。 |
| 英文摘要 | Organic micro-pollutants in water had adverse impacts on ecological environment and human health. Hence, with growing environmental concerns worldwide, efforts are now focused on the removal of organic micro-pollutants from aqueous solution. In this scenario, mixed-valence biologically produced manganese oxides (BioMnOx) and chemically produced manganese oxides (MnOx) nanoparticles were prepared. Pharmaceuticals and chlorophenols were chosen as the target contaminants. The relationship between the structure and reactivity of manganese oxides was elucidated, the reaction mechanism was proposed in detail, and then the oxygen self-activation system on nanomaterials surface was obtained base on the study results.The main research contents and results in this study are listed as followed: (1) Preparation and reactivity of BioMnOx A series of different BioMnOx materials were synthesized by the oxidation of Mn(II) with Mn-oxidizing bacteria Pseudomonas sp. G7. BioMnOx(0.4)-7, with mixed valence of Mn(II/III/IV), exhibited high activity for pharmaceuticals and natural humic acid degradation, which could be oxidized to small organic acids. There were no Mn(II) release in the reaction process, maintaining the stability of material structure. Meantime, this BioMnOx was used to load on Al2O3 balls in fixed bed reactor, and we found that the system had the high purifying capacity. (2) The mechanism of organic pollutants degradation by BioMnOx The mixed valence of Mn(II/III/IV) in BioMnOx enhanced the electron transfer on water-solid interface, causing the interaction of oxygen in water with the reduced manganese in BioMnOx to form superoxide racical (O2•-). Meantime, the high degradation activity of organic pollutants predominantly came from the synergy of Mn(IV) and O2•- oxidation, insuring the electron circulation between mixed valence of Mn, suppressing Mn(II) release. (3) Synthesis and reactivity of MnOx Five kinds of different MnO2 with various crystal structures (i.e., α, β, γ, δ, and λ-MnO2) were prepared via different methods. The results manifested that δ-MnO2 showed the highest activity, 88% of CIP could be removed at pH 7. Moreover, as far as 2-CP removal mechanism was concerned, the reaction of ring opening of benzene in presence of δ-MnO2 seemed to be less favorable, although dechlorination of 2-CP was easy. This implied that the oxidation ability of δ-MnO2 mainly originated from Mn(IV), and oxygen in air could not be converted to O2•- on δ-MnO2 surface. (4) Structural properties and reaction mechanism of Ce doped manganese oxides molecular sieves A novel class of mixed-valence manganese oxides molecular sieves was prepared by doping the rare earth element Ce (Ce-OMS-2). Doping Ce could increase the BET surface area, surface oxygen deficiency, and surface adsorbed oxygen. The study results confirmed that the reduced manganese Mn(II/III) could interact with surface adsorbed oxygen to form O2•-, and then the reduced manganese could convert to Mn(IV) again. Meanwhile, the degradation of CIP primarily arised from the synergy of Mn(IV) and O2•- oxidation, producing 3-butenamide, propionamide, and some small organic acids, inhibiting Mn(II) release. The catalyst kept the long-term activity and stability duing to the electron transfer process on water-solid interface. |
| 公开日期 | 2015-07-08 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15712]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 屠锦军. 纳米锰氧化物制备及催化氧化水中有机污染物的研究[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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