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Water Desalination by Flow-Electrode Capacitive Deionization in Overlimiting Current Regimes

机译:在超限电流条件下通过流动电极电容去离子进行海水淡化

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摘要

Since flow-electrodes do not have a maximum allowable charge capacity, a high salt removal rate in flow-electrode capacitive deionization (FCDI) can be achieved theoretically by simply increasing the applied voltage. However, present attempts to run FCDI at high voltages are unsatisfactory because of the instability of the module occurring in the overlimiting current regimes. To implement FCDI in the overlimiting current regimes (namely, OLC-FCDI), in this work, we analyzed the voltage-current (V-I) characteristics of several FCDI units. We confirmed that a continuous, rapid, and stable desalination performance of OLC-FCDI can be attained when the employed FCDI unit possesses a linear V- I characteristic (only one ohmic regime), which is distinct from the three V- I regimes in electrodialysis (ohmic, limiting current, and water splitting regimes) and the two in membrane capacitive deionization (ohmic and water splitting regimes). Notably, the linear V-I characteristic of FCDI requires continuous charge percolation near the boundaries of ion-exchange membranes. Effective methods include increasing the carbon content in the flow-electrodes and introducing electrical (carbon cloth) or ionic (ion-exchange resins) conductive intermediates in the solution compartment, which result in corresponding upgraded FCDI units exhibiting extremely high salt removal rates ( >100 mg m~(-2) s~(-1)), good cycling stability, and rapid seawater desalination performance under typical OLC-FCDI operation condition (27-40 g L~(-1) NaCl, 500 mA). This study can guide future research of FCDI in terms of flow-electrode preparation and device configuration optimization.
机译:由于流电极没有最大的允许电荷容量,因此从理论上讲,可以通过简单地增加施加电压来实现流电极电容去离子(FCDI)中的高除盐率。然而,由于在超限电流状态下发生模块的不稳定性,目前在高电压下运行FCDI的尝试并不令人满意。为了在超限电流方案(即OLC-FCDI)中实现FCDI,在这项工作中,我们分析了多个FCDI单元的电压-电流(V-I)特性。我们确认,当使用的FCDI单元具有线性V-I特性(仅一个欧姆状态)时,可以实现OLC-FCDI的连续,快速和稳定的脱盐性能,这与电渗析中的三个V-I模式不同(欧姆,极限电流和水分解方案)和膜电容去离子中的两者(欧姆和水分解方案)。值得注意的是,FCDI的线性V-I特性要求在离子交换膜的边界附近发生连续的电荷渗滤。有效的方法包括增加流电极中的碳含量,并在溶液室中引入电(碳布)或离子(离子交换树脂)导电中间体,从而导致相应的升级版FCDI装置具有极高的除盐率(> 100)毫克m〜(-2)s〜(-1)),良好的循环稳定性和典型的OLC-FCDI操作条件(27-40 g L〜(-1)NaCl,500 mA)下的快速海水淡化性能。该研究可以指导FCDI在流电极制备和设备配置优化方面的未来研究。

著录项

  • 来源
    《Environmental Science & Technology》 |2020年第9期|5853-5863|共11页
  • 作者

    Kexin Tang; Kun Zhou;

  • 作者单位

    Environmental Process Modelling Centre Nanyang Environment and Water Research Institute Nanyang Technological University Singapore 637141 Singapore;

    Environmental Process Modelling Centre Nanyang Environment and Water Research Institute School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore 637141 Singapore;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-18 05:27:33

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