Department of Chemical Engineering, Hefei University of Technology, Hefei, 230009, China.
J Phys Chem A. 2013 Jun 6;117(22):4627-35. doi: 10.1021/jp4014543. Epub 2013 May 22.
Due to the high redox activity of Fe(II) and its abundance in natural waters, the electro-oxidation of Fe(II) can be found in many air-cathode fuel cell systems, such as acid mine drainage fuel cells and sediment microbial fuel cells. To deeply understand these iron-related systems, it is essential to elucidate the kinetics and mechanisms involved in the electro-oxidation of Fe(II). This work aims to develop a kinetic model that adequately describes the electro-oxidation process of Fe(II) in air-cathode fuel cells. The speciation of Fe(II) is incorporated into the model, and contributions of individual Fe(II) species to the overall Fe(II) oxidation rate are quantitatively evaluated. The results show that the kinetic model can accurately predict the electro-oxidation rate of Fe(II) in air-cathode fuel cells. FeCO3, Fe(OH)2, and Fe(CO3)2(2-) are the most important species determining the electro-oxidation kinetics of Fe(II). The Fe(II) oxidation rate is primarily controlled by the oxidation of FeCO3 species at low pH, whereas at high pH Fe(OH)2 and Fe(CO3)2(2-) are the dominant species. Solution pH, carbonate concentration, and solution salinity are able to influence the electro-oxidation kinetics of Fe(II) through changing both distribution and kinetic activity of Fe(II) species.
由于 Fe(II) 的高氧化还原活性及其在天然水中的丰富含量，Fe(II)的电氧化可以在许多空气阴极燃料电池系统中找到，如酸性矿山排水燃料电池和沉积物微生物燃料电池。为了深入了解这些与铁有关的系统，阐明 Fe(II)电氧化过程中的动力学和机制至关重要。本工作旨在开发一个能够充分描述空气阴极燃料电池中 Fe(II)电氧化过程的动力学模型。将 Fe(II)的形态纳入模型中，并定量评估了各个 Fe(II)物种对总 Fe(II)氧化速率的贡献。结果表明，该动力学模型能够准确预测空气阴极燃料电池中 Fe(II)的电氧化速率。FeCO3、Fe(OH)2 和 Fe(CO3)2(2-)是决定 Fe(II)电氧化动力学的最重要物种。在低 pH 值下，Fe(II)的氧化主要受 FeCO3 物种的氧化控制，而在高 pH 值下，Fe(OH)2 和 Fe(CO3)2(2-)是主要的物种。溶液 pH 值、碳酸盐浓度和溶液盐度可以通过改变 Fe(II)物种的分布和动力学活性来影响 Fe(II)的电氧化动力学。
