电化学体系中羟基自由基的检测及生成规律的影响研究

发布时间：2018-06-18 22:01

  本文选题：·OH自由基 + 电化学氧化　； 参考：《西安建筑科技大学》2015年硕士论文

【摘要】：随着我国工业的迅猛发展,由工业废水排放引发的水污染问题日渐引起人们的广泛关注。其中生物难降解有机废水由于处理难度大,采用传统的方法很难达到满意的效果,而电化学氧化技术是一种新型绿色的生物难降解有机废水处理技术,具有兼容性好、处理效率佳、不易产生二次污染、操作简便、易于实现自动化等优势,近年来成为国内外研究者广泛关注的热点领域。电化学氧化技术主要通过产生强氧化剂——羟基自由基(·OH),使得有机污染物被氧化降解。因此,对·OH自由基的生成及影响规律进行检测,对于优化反应条件和反应器设计,深入研究有机物的电化学氧化机理具有重要的意义。本论文采用电沉积法制备出了以[emim]BF4离子液体为添加剂的高性能Ti/Pb O2电极,通过SEM、XRD、苯酚模拟废水降解实验和强化寿命测试等方法对自制Ti/Pb O2电极的表面形貌、电极活性及稳定性进行了表征。研究结果显示:50℃时添加50mg/L[emim]BF4离子液体制备得到的电极结晶良好,沉积层均匀致密,且电极活性较高、稳定性较好,可以用作电化学氧化体系中·OH自由基的产生电极。使用高效液相色谱-紫外检测技术(HPLC-UV),分别以水杨酸(SA)和4-羟基苯甲酸(4-HBA)为捕捉剂测定电化学氧化体系中生成的·OH自由基。色谱分离条件为:柱温为30℃、流动相为40%(v/v)甲醇:60%(v/v)超纯水、流速为1m L/min、每次进样20μL。研究结果显示,SA和4-HBA分别与·OH自由基的电化学氧化反应均符合一级反应动力学,反应速率常数分别为2.1833×10-4s-1和1.3500×10-4s-1;SA的捕捉能力为4-HBA的3倍,相较而言SA具有更高的灵敏度。因此SA为更适宜本研究体系的捕捉剂。以SA为捕捉剂,从电解液性质、电解反应器条件和外部能量输入等角度探寻不同的电化学氧化条件对·OH自由基生成的影响规律。结果表明:随着电解液p H值的增大,·OH自由基的生成速率逐步增加,碱性条件下更有利于·OH自由基的生成;电流密度的增加使得·OH自由基生成速率逐渐增加,当电流密度大于10m A/cm2时,·OH自由基生成速率的增加趋势逐渐平缓;使用较低浓度范围的支持电解质,·OH自由基的生成速率先增大后减小,0.03mol/L无水Na2SO4更适合本研究体系;无机抑制剂对·OH自由基生成的抑制作用强于有机抑制剂,且Na2CO3对·OH自由基生成的抑制作用最强;随着极板间距的增加,·OH自由基生成速率先增加后减小,当极板间距为3cm时·OH自由基生成速率最高;阴极材料为不锈钢时可实现节约能耗的目标。
[Abstract]:With the rapid development of industry in China, water pollution caused by industrial wastewater discharge has attracted more and more attention. Because of the difficulty in the treatment of biodegradable organic wastewater, it is difficult to achieve satisfactory results by using traditional methods. However, electrochemical oxidation is a new type of green biodegradable organic wastewater treatment technology, which has good compatibility. In recent years, the advantages of high efficiency, easy to produce secondary pollution, simple operation and easy to realize automation have become the focus of attention of researchers at home and abroad. Electrochemical oxidation technology mainly produces strong oxidant-hydroxyl radical (OHN), which results in the oxidative degradation of organic pollutants. Therefore, the detection of the formation and influence of OH radicals is of great significance for optimizing the reaction conditions and reactor design and studying the electrochemical oxidation mechanism of organic compounds. In this paper, the high performance Ti- / PbO2 electrode with [emim] BF4 ionic liquid as additive was prepared by electrodeposition method. The surface morphology of self-made Ti / PbO2 electrode was studied by means of SEMX XRD, phenol simulated wastewater degradation experiment and enhanced lifetime test. The electrode activity and stability were characterized. The results show that the electrode prepared by adding 50mg / L [emim] BF4 ionic liquid at 50 鈩，

本文编号：2037007