Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, 405 rue de Vandœuvre, F-54600 Villers-lès-Nancy, France; CNRS, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, 405 rue de Vandœuvre, F-54600 Villers-lès-Nancy, France.
Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, 405 rue de Vandœuvre, F-54600 Villers-lès-Nancy, France; CNRS, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, 405 rue de Vandœuvre, F-54600 Villers-lès-Nancy, France.
Water Res. 2014 Oct 1;62:29-39. doi: 10.1016/j.watres.2014.05.028. Epub 2014 May 28.
The reduction of nitrate anions by a mixed Fe(II)-Fe(III) carbonated green rust (GR) in aqueous medium is studied as a function of the initial pH and the initial concentrations of iron, phosphate and nitrate. The influence of these parameters on the fraction of nitrate removed and the production of ammonium is investigated by the help of statistical experimental designs. The goal is to determine experimental conditions that maximize the fraction of NO3(-) removed and concomitantly minimize the production of NH4(+). Increasing the phosphate concentration relatively to the initial Fe(II) concentration inhibits the reduction of nitrate probably due to a surface saturation of the lateral sites of the GR crystals. The kinetics of the reaction is greatly enhanced by increasing the initial pH at 10.5, however it leads to a global increase of the NH4(+) production. A partial saturation of the surface sites by phosphate leads to a global decrease of selectivity of the reaction towards ammonium. The evolution of the ratio of the NH4(+) concentration to the Fe(II) concentration confirms that the NO3(-) species are only partially transformed into ammonium. Interestingly at an initial pH of 7.5, the selectivity of the reaction towards NH4(+) is often lower than ∼30%. The reduction of nitrate by carbonated GR differs from the behavior of other GRs incorporating Cl(-), F(-) and SO4(2-) anions that fully transform nitrate into ammonium. Finally, if GR is intended to be used during a passive water denitrification process, complementary dephosphatation and ammonium treatments should be considered.
研究了混合 Fe(II)-Fe(III)碳酸绿锈（GR）在水溶液中还原硝酸盐阴离子的过程，其影响因素包括初始 pH 值、铁、磷酸盐和硝酸盐的初始浓度。通过统计实验设计研究了这些参数对硝酸盐去除率和铵生成率的影响。目的是确定能最大程度去除硝酸盐且同时最小化铵生成的实验条件。与初始 Fe(II)浓度相比，增加磷酸盐浓度可能会由于 GR 晶体的横向位点表面饱和而抑制硝酸盐的还原。在 10.5 时增加初始 pH 值会极大地促进反应动力学，但会导致铵生成量的整体增加。通过磷酸盐部分饱和表面位点，反应对铵的选择性会全面降低。铵浓度与 Fe(II)浓度之比的变化证实，NO3(-)物种仅部分转化为铵。有趣的是，在初始 pH 值为 7.5 时，反应对 NH4(+)的选择性通常低于约 30%。碳酸 GR 还原硝酸盐的行为与其他含有 Cl(-)、F(-)和 SO4(2-)阴离子的 GR 不同，后者将硝酸盐完全转化为铵。最后，如果 GR 计划在被动水脱硝过程中使用，还应考虑进行除磷和铵处理。
