晶体结构对电极材料的电化学性能有显著影响,从而影响电极的电催化活性。在这项工作中,α-,β-,并制作了γ-MnO2电极,用于研究晶体结构对N的电氧化处理的影响,含N-二甲基乙酰胺(DMAC)的废水。通过扫描电子显微镜和X射线衍射对制备的MnO2电极进行了表征,表明成功制备了具有相同堆积针状结构的不同晶体结构的MnO2电极。电化学性能,包括DMAC的去除效率,化学需氧量(COD)和总氮(TN),和能源消耗,在不同的MnO2电极之间进行了比较。结果表明,β-MnO2电极具有良好的电化学活性,可以删除93%的DMAC,62%COD,和78.9%的TN,远高于α-和γ-MnO2;此外,计算α-的能耗为11.3、9.7和10.5kWh/m3,β-,和γ-MnO2。此外,提出了MnO2电极的氧化机理,表明DMAC主要通过羟基化反应被羟基自由基氧化,去甲基化,和脱氨,和比表面积的电极特性,析氧电位,和羟基自由基的产生是MnO2电极上降解DMAC的关键因素。最后,用含有废水的实际DMAC测试三个电极的电化学性能,和β-MnO2电极被证实为适用于潜在应用的电极,可实现100%的去除效率,64.5%,和73%的DMAC,COD,CODTN,分别,系统优化后。
The crystal structure has a significant impact on the electrochemical properties of electrode material, and thus influences the electrocatalytic activity of the electrode. In this work, α-, β-, and γ-MnO2 electrodes were fabricated and applied for investigating the effect of crystal structure on electro-oxidation treatment of N,N-dimethylacetamide (DMAC) containing wastewater. The prepared MnO2 electrodes were characterized by scanning electron microscopy and X-ray diffraction, suggesting that different crystal structures of MnO2 electrodes with the same morphology of stacking-needle structure were successfully prepared. The electrochemical performances, including removal efficiencies of DMAC, chemical oxygen demand (COD) and total nitrogen (TN), and energy consumption, were compared between different MnO2 electrodes. Results indicated that β-MnO2 electrode presented the excellent electrochemical activity, and could remove 93% DMAC, 62% COD, and 78.9% TN, which was much higher than that of α- and γ-MnO2; moreover, energy consumptions of 11.3, 9.7, and 10.5 kWh/m3 were calculated for α-, β-, and γ-MnO2, respectively. Additionally, the oxidation mechanism of the MnO2 electrodes was presented, indicating that DMAC was mainly oxidized by hydroxyl radical through reactions of hydroxylation, demethylation, and deamination, and electrode characteristics of specific surface area, oxygen evolution potential, and hydroxyl radical production were the key factors for degrading DMAC on MnO2 electrodes. Finally, an actual DMAC containing wastewater was applied for testing the electrochemical performance of the three electrodes, and β-MnO2 electrode was verified as the suitable electrode for potential application which achieved removal efficiencies of 100%, 64.5%, and 73% for DMAC, COD, and TN, respectively, after system optimization.