Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
J Hazard Mater. 2016 May 5;308:208-15. doi: 10.1016/j.jhazmat.2016.01.047. Epub 2016 Jan 22.
The mechanism of the effects of Fe(2+)(aq) on the reduction of NO3(-) by Fe(0) was investigated. The effects of initial pH on the rate of NO3(-) reduction and the Fe(0) surface characteristics revealed Fe(2+)(aq) and the characteristics of minerals on the surface of Fe(0) played an important role in NO3(-) reduction. Both NO3(-) reduction and the decrease of Fe(2+)(aq) exhibited similar kinetics and were promoted by each other. This promotion was associated with the types of the surface iron oxides of Fe(0). Additionally, further reduction of NO3(-) produced more surface iron oxides, supplying more active sites for Fe(2+)(aq), resulting in more electron transfer between Fe(2+) and surface iron oxides and a higher reaction rate. Using the isotope specificity of (57)Fe Mossbauer spectroscopy, it was verified that the Fe(2+)(aq) was continuously converted into Fe(3+) oxides on the surface of Fe(0) and then converted into Fe3O4 via electron transfer between Fe(2+) and the pre-existing surface Fe(3+) oxides. Electrochemistry measurements confirmed that the spontaneous electron transfer between the Fe(2+) and structural Fe(3+) species accelerated the interfacial electron transfer between the Fe species and NO3(-). This study provides a new insight into the interaction between Fe species and contaminants and interface electron transfer.
研究了 Fe(2+)(aq)对 Fe(0)还原 NO3(-)的影响机制。初始 pH 值对 NO3(-)还原速率和 Fe(0)表面特性的影响表明，Fe(2+)(aq)和 Fe(0)表面矿物质的特性在 NO3(-)还原中起着重要作用。NO3(-)还原和 Fe(2+)(aq)的减少都表现出相似的动力学，并且彼此促进。这种促进与 Fe(0)表面氧化铁的类型有关。此外，进一步还原 NO3(-)产生更多的表面氧化铁，为 Fe(2+)(aq)提供更多的活性位点，导致 Fe(2+)和表面氧化铁之间更多的电子转移和更高的反应速率。利用 (57)Fe Mossbauer 光谱的同位素特异性，证实 Fe(2+)(aq)在 Fe(0)表面上不断转化为 Fe(3+)氧化物，然后通过 Fe(2+)和预先存在的表面 Fe(3+)氧化物之间的电子转移转化为 Fe3O4。电化学测量证实，Fe(2+)和结构 Fe(3+)物种之间的自发电子转移加速了 Fe 物种与 NO3(-)之间的界面电子转移。本研究为 Fe 物种与污染物之间的相互作用和界面电子转移提供了新的见解。
