Thermodynamic Consideration on Degradation of Humic Acids by Electrolysis
Thermodynamic Consideration on Degradation of Humic Acids by Electrolysis
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DOI：
10.5796/electrochemistry.82.19
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发表时间：
2014-01
期刊：
影响因子：
2.5
通讯作者：
Shunsuke Yagi;K. Nakatsuji;Yuichi Satake;A. Nakahira;M. Anpo
中科院分区：
文献类型：
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作者：
Shunsuke Yagi;K. Nakatsuji;Yuichi Satake;A. Nakahira;M. Anpo
摘要利用电位-pH图从热力学角度研究了在Na 2SO 4和NaCl水溶液中电解降解腐殖酸的机理。HA降解建议进行在阳极通过形成高氧化性的硫酸和氯物种，如S2 O2 8，ClO 2，和ClO。在同时存在SO 4和Cl −的情况下，由于Cl−/ClO 2和Cl −/ClO−氧化还原电对的氧化还原电位远低于SO 4 /S2 O28氧化还原电对的氧化还原电位，氧化性氯物种优先在阳极形成.吸收光谱随时间的变化表明，S2 O2 8离子对HA的降解程度高于氧化性氯离子，但降解速率要慢得多.这是由于S2 O28离子的形成速率低。线性扫描伏安法还表明，形成的氧化性氯物种是快速的和可比的O2生成速率。
ABSTRACT The degradation mechanism of humic acids (HAs) by electrolysis in aqueous solutions of Na2SO4 and/or NaCl was examined within a thermodynamics context using potential–pH diagrams. HA degradation is suggested to proceed at the anode through the formation of highly oxidizing sulfuric and chlorine species such as S2O 2 8 , ClO 2 , and ClO . In the presence of both SO 4 and Cl − ions, oxidizing chlorine species were found to form preferentially at the anode partly because of the much lower redox potentials of the Cl−/ClO 2 and Cl −/ClO− redox couples compared with that of the SO 4 /S2O 2 8 redox couple. The change in absorption spectra with time indicated that the degree of HA degradation by S2O 2 8 ions is higher than that of oxidizing chlorine species, although the degradation rate is much slower. This is attributed to the low formation rate of S2O 2 8 ions. Linear sweep voltammetry also revealed that the formation of the oxidizing chlorine species was fast and comparable to the rate of O2 generation.