零价Mn促进Fe/C微电解反应速率及降解污染物机理

Mechanisms on Zerovalent Mn promotes Fe/C microelectrolysis reaction rate and degrades pollutants

摘要:

铁碳微电解工艺处理废水效率低,易出现板结问题,仅适用于处理酸性废水。为了扩宽铁碳微电解工艺的适用范围及提高处理效率,研究采用添加零价Mn构建Fe/Mn/C三元微电解体系处理甲基橙(MO)模拟染料废水。利用SEM-EDS、傅里叶红外光谱及拉曼光谱分析铁、锰和活性碳表面形貌的变化及元素组成,采用紫外可见光谱和三维荧光光谱等探究有机物成分的变化,对比Fe/Mn/C和Fe/C微电解体系对甲基橙的降解效果,揭示Fe/Mn/C三元微电解体系降解甲基橙的反应机理和反应动力学。结果表明：反应后的铁、锰、碳填料表面存在铁氧化物、氢氧化物及锰氧化物,Fe/Mn/C三元微电解可断裂甲基橙的氮氮双键,破坏苯环结构。甲基橙的降解过程符合二级反应动力学；Fe/C微电解体系加入零价Mn后,甲基橙降解的反应速率常数由5.7381×10_^-4 min_^?1提高至9.38336×10_^-4 min_^?1,降解速率和降解效果显著优于Fe/C微电解。

Abstract:

Fe/C microelectrolysis process has low wastewater treatment efficiency and is prone to hardening problems, and is only suitable for treating acidic wastewater. In order to broaden the application range of Fe/C microelectrolysis process and improve the treatment efficiency, Fe/Mn/C ternary microelectrolysis system was constructed by adding zerovalent Mn and methyl orange (MO) simulated dye wastewater was treated. The morphology changes of iron, manganese and carbon and the compositions of surface elements were analyzed using SEM-EDS, Fourier transform infrared spectroscopy and Raman spectra. The changes of organic compounds in the wastewater were explored using UV-Vis spectra and three-dimensional fluorescence spectra before and after the reaction. Degradation performance of methyl orange was compared between Fe/Mn/C microelectrolysis and Fe/C microelectrolysis. Reaction mechanisms and reaction kinetics of methyl orange degradation were revealed using Fe/Mn/C ternary microelectrolysis system. The results showed that iron oxides, hydroxides and manganese oxides were existed on the surface of iron, manganese and carbon after the reaction. Fe/Mn/C ternary microelectrolysis broke nitrogen-nitrogen double bond of methyl orange and destroyed the structure of benzene ring. The degradation process of methyl orange conformed to second-order kinetics. After zero-valent Mn was added into Fe/C binary microelectrolysis system, the reaction efficiency constant of methyl orange degradation increased from 5.7381×10_^-4min_^?1 to 9.38336×10_^-4min_^?1. The degradation rate and degradation effect of methyl orange in the Fe/Mn/C microelectrolysis system was significantly better than those in the Fe/C microelectrolysis system.