Oxidation of organics in water in microfluidic electrochemical reactors: Theoretical model and experiments
Oxidation of organics in water in microfluidic electrochemical reactors: Theoretical model and experiments
复制标题
DOI：
10.1016/j.electacta.2011.09.073
复制
发表时间：
2011-12
影响因子：
6.6
通讯作者：
O. Scialdone;C. Guarisco;A. Galia
中科院分区：
文献类型：
--
作者：
O. Scialdone;C. Guarisco;A. Galia
以掺硼金刚石(BDD)为阳极，在微反中对水中有机物的电化学氧化进行了理论和实验研究，以期找到各种操作参数对转化率和电流效率CE的影响。以甲酸(FA)的电化学氧化为模型。在适当的停留时间和较小的阴阳极距离下，电解液在电解槽内的单程转化率较高。详细考察了初始浓度、流速和电流密度对电极性能的影响。对于传质控制、氧化反应控制和混合动力学区域，尽管没有使用可调的参数，但理论预测与实验结果非常吻合。为简单起见，对于没有高电流强度的过程，通过考虑恒定的Sh数(例如，恒定的传质系数Km)，以最小化气体鼓泡对流动动力学模式的影响，成功地模拟了传质过程。对于混合动力学体系，使用了两种不同的建模方法。在第一种情况下，BDD中有机物的氧化被认为是传质控制的，当外加电流密度高于极限电流密度时，发生本征的100%CE。在第二种情况下，对过程的CE进行了模拟，假设有机和水氧化之间的竞争仅取决于电极材料以及有机物的性质和浓度。在后一种情况下，实验数据和理论预测之间有较好的一致性。
The electrochemical oxidation of organics in water performed in micro reactors on boron doped diamond (BDD) anode was investigated both theoretically and experimentally in order to find the influence of various operative parameters on the conversion and the current efficiency CE of the process. The electrochemical oxidation of formic acid (FA) was selected as a model case. High conversions for a single passage of the electrolytic solution inside the cell were obtained by operating with proper residence times and low distances between cathode and anode. The effect of initial concentration, flow rate and current density was investigated in detail. Theoretical predictions were in very good agreement with experimental results for both mass transfer control, oxidation reaction control and mixed kinetic regimes in spite of the fact that no adjustable parameters was used. Mass transfer process was successfully modelled by considering for simplicity a constant Sh number (e.g., a constant mass transfer coefficient km) for a process performed with no high values of the current intensity to minimize the effect of the gas bubbling on the flowdynamic pattern. For mixed kinetic regimes, two different modelling approaches were used. In the first one, the oxidation of organics at BDD was assumed to be mass transfer controlled and to occur with an intrinsic 100% CE when applied current density is higher than the limiting current density. In the second case, the CE of the process was modelled assuming that the competition between organic and water oxidation depends only on the electrodic material and on the nature and the concentration of the organic. In the latter case a better agreement between experimental data and theoretical predictions was observed.