Jiang Jin, Pang Su-Yan, Ma Jun
State Key Laboratory of Urban Water Resource and Environment, National Engineering Research Center of Urban Water Resources, Harbin Institute of Technology, Harbin 150090, China.
Environ Sci Technol. 2009 Nov 1;43(21):8326-31. doi: 10.1021/es901663d.
Experiments were conducted to examine permanganate (Mn(VII); KMnO(4)) oxidation of the widely used biocide triclosan (one phenolic derivative) in aqueous solution at pH values of 5-9. Under slightly acidic conditions, the reactions displayed autocatalysis, suggesting the catalytic role of in situ formed MnO(2). This was further supported by the promoting effects of the addition of preformed MnO(2) colloids on Mn(VII) oxidations of triclosan and two other selected phenolics (i.e., phenol and 2,4-dichlorophenol), as well as p-nitrophenol which otherwise showed negligible reactivity toward Mn(VII) and MnO(2) colloids, respectively. Surprisingly, phosphate buffer significantly enhanced Mn(VII) oxidation of triclosan, as well as phenol and 2,4-dichlorophenol over a wide pH range. Further, several other selected ligands (i.e., pyrophosphate, EDTA, and humic acid) also exerted oxidation enhancement, supporting a scenario where highly active aqueous manganese intermediates (Mn(INT)(aq)) formed in situ upon Mn(VII) reduction might be stabilized to a certain extent in the presence of ligands and subsequently involved in further oxidation of target phenolics, whereas without stabilizing agents Mn(INT)(aq) autodecomposes or disproportionates spontaneously. The effectiveness of Mn(VII) for the oxidative removal of triclosan in natural water and wastewater was confirmed. Their background matrices were also found to accelerate Mn(VII) oxidation of phenolics.
开展了实验，以研究在pH值为5 - 9的水溶液中，高锰酸盐（Mn(VII)；KMnO₄）对广泛使用的杀菌剂三氯生（一种酚类衍生物）的氧化作用。在略酸性条件下，反应呈现出自催化作用，这表明原位生成的MnO₂具有催化作用。预先形成的MnO₂胶体对三氯生以及另外两种选定酚类（即苯酚和2,4 - 二氯苯酚）的Mn(VII)氧化具有促进作用，这进一步证明了上述结论，此外，对硝基苯酚对Mn(VII)和MnO₂胶体的反应活性可忽略不计。令人惊讶的是，磷酸盐缓冲液在很宽的pH范围内显著增强了三氯生以及苯酚和2,4 - 二氯苯酚的Mn(VII)氧化作用。此外，其他几种选定的配体（即焦磷酸盐、乙二胺四乙酸和腐殖酸）也具有氧化增强作用，这支持了这样一种情况：Mn(VII)还原时原位形成的高活性水合锰中间体（Mn(INT)(aq)）在配体存在下可能会在一定程度上得到稳定，随后参与目标酚类的进一步氧化，而没有稳定剂时，Mn(INT)(aq)会自发分解或歧化。证实了Mn(VII)对天然水和废水中三氯生的氧化去除效果。还发现它们的背景基质会加速酚类的Mn(VII)氧化。
