电流密度对BDD电极电化学矿化吲哚的影响与机制

发布时间：2018-02-25 22:04

本文关键词： 掺硼金刚石膜电极吲哚矿化气体逸出碳守恒氮形态　出处：《环境科学》2017年09期 　论文类型：期刊论文

【摘要】：掺硼金刚石膜(BDD)电极电化学氧化法是去除难降解有机污染物的有效手段.与总有机碳(TOC)等的测定相比,气态中间产物的逸出量能够更直观有效地反映有机物的矿化程度与去除效果.本研究以吲哚为代表性污染物,通过对比不同电流密度(10、20和30 m A·cm-2)下BDD电极对吲哚的去除率与矿化率,结合降解过程中碳和氮形态的变化与守恒情况,分析吲哚的降解机制.结果表明,BDD电极对吲哚有良好的去除效果,电流密度为10、20、30 m A·cm-2时,吲哚达到100%去除的时间分别为8、5和4 h;TOC去除率、CO_2产生量均随电流密度的增加而增大,证明矿化率与电流密度成正相关;电解产生的CO_2气体与TOC、无机碳(TIC)构成了碳守恒体系.4~5 h时,体系TOC、TON和CO_2产生量均没有变化,表明电解产生的靛红具有较高的稳定性,此时为中间产物积累阶段;XPS表征进一步证实了中间产物靛红、苯醌等在电极表面的吸附,随着电解时间的延长,这些吸附的中间产物可进一步被降解.本研究从气态产物检测及碳氮形态分析与守恒的角度阐释吲哚矿化过程,对于辅助揭示有机物的电解过程有重要意义.
[Abstract]:The electrochemical oxidation of boron doped diamond (BDD) electrode is an effective method to remove refractory organic pollutants, compared with the determination of total organic carbon (TOC), etc. The emission of gaseous intermediate products can reflect the mineralization degree and removal efficiency of organic compounds more directly and effectively. In this study, indole was used as the representative pollutant. By comparing the removal rate and mineralization rate of indole at BDD electrode at different current densities of 10 ~ (20) and 30 Ma 路cm ~ (-2), the change and conservation of carbon and nitrogen forms in the degradation process were combined. The degradation mechanism of indole was analyzed. The results showed that the removal efficiency of indole was good. When the current density was 10 ~ 20 ~ 30 Ma 路cm-2, the removal time of indole to 100% was 8 ~ 5 and 4 h respectively. The yield of indoles increased with the increase of current density. It is proved that the mineralization rate is positively correlated with the current density, and that the CO_2 gas produced by electrolysis has no change in the production of both TOCITon and CO_2, and that the CO_2 gas produced by electrolysis has a high stability with respect to the formation of the conserved carbon system for 5 h, and the amount of CO_2 produced by the system does not change, which indicates that the indirubin produced by electrolysis is of high stability. XPS characterization at this stage of intermediate product accumulation further confirmed the adsorption of indirubin and benzoquinone on the electrode surface with the prolongation of electrolysis time. These adsorbed intermediates can be further degraded. In this study, the indole-mineralization process was explained from the point of view of gaseous product detection, carbon and nitrogen speciation analysis and conservation, which is of great significance in assisting to reveal the electrolytic process of organic matter.
【作者单位】：北京大学环境工程系水沙科学教育部重点实验室;
【基金】：国家重点研发计划项目(2016YFC0402102)
【分类号】：X592

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