阳极氧化法制备纳米氧化锌用于光催化降解苯酚的研究

发布时间：2018-05-26 04:22

  本文选题：纳米氧化锌 + 阳极氧化法　； 参考：《太原理工大学》2015年硕士论文

【摘要】：随着环境问题越来越严重，水污染的处理不断受到重视，特别是水中难以降解的酚类有机污染物。现在研究最多的是光催化氧化降解法，常用的光催化剂是半导体金属氧化物，其中氧化锌作为新型宽禁带半导体材料，因其对紫外光吸收能力强、表面羟基含量高、形貌多样化等优点而逐渐被关注，且光催化反应机理与TiO2相似，有望取代TiO2。 本研究在氯化铵、无水乙醇、蒸馏水、双氧水组成的电解液中采用电化学阳极氧化法制备出高比例暴露极性面的片状纳米氧化锌，并用于光催化降解苯酚溶液。主要研究内容及结论如下： 1．分别在不同类型的电解液、不同的醇类、不同的电解质配制成的电解液中进行阳极氧化反应，并用SEM表征得到的产物，可知氯化铵作为电解质，水和无水乙醇各半作为溶剂制备出来的氧化锌形貌最好。在此基础上改变反应参数，通过正交试验发现：电压7V、氧化时间25min、NH4Cl质量分数为1.20%、30%双氧水的体积为0.4ml条件下制备得到的片状纳米氧化锌晶体结构均一，表面清洁，无团聚。 2.对焙烧前后的纳米氧化锌进行XRD、FT-IR、BET表征，发现未焙烧的纳米氧化锌含有大量的羟基和少量的氯离子，还有很强的O－C＝O、－OH红外吸收峰，其比表面积比焙烧后的氧化锌大；在325℃焙烧4h后的纳米氧化锌，其XRD衍射峰峰型尖锐、半峰宽较窄，也没有出现杂峰，即焙烧后的纳米氧化锌的结晶度和纯度都很高，但其O－C＝O、－OH红外吸收峰的强度变弱。 3.通过比较焙烧前后实验制备的纳米氧化锌、商品纳米氧化锌对苯酚溶液的光催化氧化降解效率可以发现：实验制备的片状纳米氧化锌在焙烧前对苯酚的降解效率最高，120min结束反应后对苯酚的降解效率为73.36%。降解主要发生在前60min，随着苯酚浓度的降低，催化速率也在降低。在光催化反应过程中，，曝入氧气对苯酚的降解效率也有较大的提高。 4.通过对片状纳米氧化锌进行光致发光和拉曼光谱分析，可知实验制备的片状纳米氧化锌的紫外发光峰向可见光区移动且宽化，可见光区发光峰也比较强，拉曼光谱也发生了红移现象，进一步表明实验制备的片状纳米氧化锌含有比较多的氧空缺等缺陷，正是这些缺陷使得纳米片状氧化锌表现出更高的光催化活性。
[Abstract]:As the environmental problems become more and more serious, the treatment of water pollution has been paid more and more attention, especially the phenolic organic pollutants which are difficult to degrade in water. The photocatalytic degradation method is the most widely studied now. The commonly used photocatalyst is semiconductor metal oxide, among which zinc oxide is a new wide band gap semiconductor material, because of its strong absorbability to ultraviolet light and high content of hydroxyl group on the surface. The mechanism of photocatalytic reaction is similar to that of TiO2, which is expected to replace TIO _ 2. In this paper, a high proportion of sheet zinc oxide was prepared by electrochemical anodization in the electrolyte composed of ammonium chloride, anhydrous ethanol, distilled water and hydrogen peroxide, and used for photocatalytic degradation of phenol solution. The main contents and conclusions are as follows: 1. Anodic oxidation reaction was carried out in different electrolytes, different alcohols and different electrolytes respectively. The products were characterized by SEM, and ammonium chloride was used as electrolyte. The morphology of zinc oxide prepared by water and anhydrous ethanol is the best. On this basis, the reaction parameters were changed. It was found by orthogonal experiment that the structure of ZnO was uniform, the surface was clean and there was no agglomeration under the condition that the voltage was 7V, the mass fraction of NH _ 4Cl was 1.20% and the mass fraction of NH _ 4Cl was 1.20% hydrogen peroxide, and the volume of hydrogen peroxide was 0.4ml. 2. The nanometer zinc oxide before and after calcination was characterized by XRDX FT-IR BET. It was found that the uncalcined nanometer zinc oxide contained a large amount of hydroxyl groups and a small amount of chloride ions, and there was also a strong infrared absorption peak of O-C _ (10) O _ (-) O _ (-OH), and its specific surface area was larger than that of the calcined zinc oxide. After calcined at 325 鈩

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