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Long-lasting, monovalent-selective capacitive deionization electrodes
npj Clean Water ( IF 11.4 ) Pub Date : 2021-03-26 , DOI: 10.1038/s41545-021-00109-2
Eric N. Guyes , Amit N. Shocron , Yinke Chen , Charles E. Diesendruck , Matthew E. Suss

Emerging water purification applications often require tunable and ion-selective technologies. For example, when treating water for direct use in irrigation, often monovalent Na+ must be removed preferentially over divalent minerals, such as Ca2+, to reduce both ionic conductivity and sodium adsorption ratio (SAR). Conventional membrane-based water treatment technologies are either largely non-selective or not dynamically tunable. Capacitive deionization (CDI) is an emerging membraneless technology that employs inexpensive and widely available activated carbon electrodes as the active element. We here show that a CDI cell leveraging sulfonated cathodes can deliver long-lasting, tunable monovalent ion selectivity. For feedwaters containing Na+ and Ca2+, our cell achieves a Na+/Ca2+ separation factor of up to 1.6. To demonstrate the cell longevity, we show that monovalent selectivity is retained over 1000 charge–discharge cycles, the highest cycle life achieved for a membraneless CDI cell with porous carbon electrodes to our knowledge, while requiring an energy consumption of ~0.38 kWh/m3 of treated water. Furthermore, we show substantial and simultaneous reductions of ionic conductivity and SAR, such as from 1.75 to 0.69 mS/cm and 19.8 to 13.3, respectively, demonstrating the potential of such a system towards single-step water treatment of brackish and wastewaters for direct use in irrigation.



中文翻译:

持久的单价选择性电容去离子电极

新兴的净水应用通常需要可调谐和离子选择性技术。例如,在处理直接用于灌溉的水时,通常必须优先去除一价Na +而不是二价矿物(例如Ca 2+),以降低离子电导率和钠吸附率(SAR)。常规的基于膜的水处理技术要么很大程度上是非选择性的,要么是不可动态调节的。电容去离子(CDI)是一种新兴的无膜技术,采用廉价且广泛使用的活性炭电极作为活性元素。我们在这里表明,利用磺化阴极的CDI电池可以提供持久的,可调节的单价离子选择性。对于含有Na +和Ca的给水2+时,我们的电池达到的Na + / Ca 2+分离系数高达1.6。为了证明电池寿命,我们证明了在1000个充放电循环中保持了单价选择性,据我们所知,这是具有多孔碳电极的无膜CDI电池实现的最高循环寿命,同时需要消耗约0.38 kWh / m 3的能量处理过的水。此外,我们显示出离子导电率和SAR的同时大幅降低,例如分别从1.75降低至0.69 mS / cm和19.8降低至13.3,这表明该系统具有潜力,可用于含盐废水和直接使用废水的单步水处理在灌溉中。

更新日期:2021-03-26
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