Delft University of Technology, Department of Biotechnology, Delft, The Netherlands.
Water Res. 2011 Nov 15;45(18):5945-52. doi: 10.1016/j.watres.2011.08.056. Epub 2011 Sep 12.
Formation of the greenhouse gas nitrous oxide in water treatment systems is predominantly studied as a biological phenomenon. There are indications that also chemical processes contribute to these emissions. Here we studied the formation of nitric oxide (NO) and nitrous oxide (N(2)O) due to chemical nitrite reduction by ferrous iron (Fe(II)). Reduction of nitrite and NO coupled to Fe(II) oxidation was studied in laboratory-scale chemical experiments at different pH, nitrite and iron concentrations. The continuous measurement of both NO and N(2)O emission showed that nitrite reduction and NO reduction have different kinetics. Nitrite reduction shows a linear dependency on the nitrite concentration, implying first order kinetics in nitrite. The nitrite reduction seems to be an equilibrium based reaction, leading to a constant NO concentration in the liquid. The NO reduction rate is suggested to be most dependent on reactive surface availability and the sorption of Fe(II) to the reactive surface. The importance of emission of NO and N(2)O coupled to iron oxidation is exemplified by iron reduction experiments and several examples of environments where this pathway can play a role.
在水处理系统中，一氧化二氮（N2O）的形成主要被研究为一种生物现象。有迹象表明，化学过程也对这些排放物有贡献。在这里，我们研究了由于二价铁（Fe(II)）的化学亚硝酸盐还原而导致一氧化氮（NO）和一氧化二氮（N2O）的形成。在不同 pH 值、亚硝酸盐和铁浓度的实验室规模化学实验中，研究了亚硝酸盐和 NO 与 Fe(II)氧化偶联的还原。对两种气体排放的连续测量表明，亚硝酸盐还原和 NO 还原具有不同的动力学。亚硝酸盐还原对亚硝酸盐浓度呈线性依赖性，表明亚硝酸盐的反应级数为一级。亚硝酸盐还原似乎是一个基于平衡的反应，导致液体中 NO 浓度保持不变。NO 还原速率似乎主要取决于反应表面的可用性以及 Fe(II)对反应表面的吸附。铁还原实验和几个可能存在这种途径的环境的例子说明了与铁氧化偶联的 NO 和 N2O 排放的重要性。
