Photoelectrocatalytic degradation of triazine-containing azo dyes at gamma-Bi2MoO6 film electrode under visible light irradiation (lamda > 420 nm).
Photoelectrocatalytic degradation of triazine-containing azo dyes at gamma-Bi2MoO6 film electrode under visible light irradiation (lamda > 420 nm).
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DOI：
10.1021/es070598b
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发表时间：
2007-08
影响因子：
11.4
通讯作者：
Xu Zhao;J. Qu;Huijuan Liu;Chun Hu
中科院分区：
文献类型：
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作者：
Xu Zhao;J. Qu;Huijuan Liu;Chun Hu
在可见光照射下，研究了γ-Bi 2 MoO 6膜电极对阴离子活性艳红K-2G、活性艳红X-3B和活性黄KD-3G等含三嗪偶氮染料的电氧化、光催化及电氧化-光催化复合降解过程.通过降解动力学和总有机碳变化分析，发现在组合工艺中，染料的降解存在协同效应。利用X射线光电子能谱、电化学阻抗谱以及不同过程中电流随时间的变化规律研究了协同机理。有人建议，应用偏压具有比目标染料的氧化还原电位更低的值，有效地增加了染料通过禁止电子和空穴的重组的速率。在偏压大于染料的氧化还原电位时，电氧化与电还原相结合能有效地提高染料的降解率。通过DMPO自旋捕获电子自旋共振测量和自由基清除剂的作用证实，参与染料降解的主要活性氧物种是羟基自由基。检测到的中间产物主要是芳香族和脂肪族有机羧酸。
Triazine-containing azo dyes, anionic reactive brilliant red K-2G, reactive brilliant Red X-3B, and reactive yellow KD-3G were degraded in the electrooxidation, photocatalysis and combined electrooxidation and phtocatalysis process at the gamma-Bi2MoO6 film electrode under visible light irradiation. Furthermore, in the combined process, synergetic degradation of the dyes was observed by the analysis of degradation kinetics and total organic carbon variation. The synergetic mechanism was studied using X-ray photoelectron spectra and electrochemical impedance spectra as well as analysis of variation of current vs time in various processes. It is suggested that application of bias potential with a lower value than the redox potential of the targeted dyes efficiently increases the photocatalysis rate of the dyes by prohibiting recombination of electrons and holes. At the bias greater than the redox potential of the dyes, the degradation of the dyes was efficiently improved bythe combined electrooxidation and photocatalysis process. The main active oxygen species involved in the dyes degradation was hydroxyl radicals as confirmed via DMPO spin-trapping electron spin resonance measurements and the effect of radical scavengers. Intermediates mainly including organic aromatic and aliphatic carboxylic acids were detected.