Understanding the performance of flow-electrodes for capacitive deionization through hydrodynamic voltammetry
Understanding the performance of flow-electrodes for capacitive deionization through hydrodynamic voltammetry
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DOI：
10.1016/j.cej.2020.126826
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发表时间：
2021-02-15
影响因子：
15.1
通讯作者：
Dryfe, Robert A. W.
中科院分区：
文献类型：
--
作者：
Carmona-Orbezo, Aranzazu;Dryfe, Robert A. W.
流动电极电容去离子是扩大这种脱盐技术规模的一种很有前途的方法，因为它能够在主电池外部再生电极，从而使用碳浆作为可流动电极从进水中去除更大量的盐。以前的工作集中于通过改变流动电极组成或通过提出不同的电池设计来提高性能，使用宽范围的电极体积流速，以及考虑浆料作为牛顿流体进行数学和实验建模。在这项工作中，流体动力学伏安法是用来了解碳浆料的电化学行为，开发一种优化方法，将得到一个改进的电化学性能的浆料。结果表明，浆料的表观粘度必须被认为是解释电池内的浆料的行为，以及剪切稀化对浆料内活性炭颗粒的迁移的影响。提出了一个无量纲数来定义一个阈值，该阈值将确保流动电极的电容行为。
Flow-electrode capacitive deionization is a promising approach to scale up this desalination technology, because of its ability to regenerate the electrodes outside the main cell, and thereby remove a higher amount of salt from the feed water using carbon slurries as flowable electrodes. Previous works have focused on improving the performance by changing the flow-electrode composition or by proposing different cell designs, using a wide range of volumetric flow rates for the electrode, as well as performing mathematical and experimental modelling considering the slurries as Newtonian fluids. In this work, hydrodynamic voltammetry is used to understand the electrochemical behaviour of the carbon slurries, to develop an optimization method that will give an improved electrochemical performance of the slurries. Results show that the apparent viscosity of the slurries must be considered to explain the behaviour of the slurry within the cell, as well as the effect of shear thinning on the migration of activated carbon particles inside the slurry. A dimensionless number is proposed to define a threshold that will ensure a capacitive behaviour of the flow-electrode.