Capacitive deionization (CDI) is an environmental remediation technology that can remove aqueous ionic contaminants, but a major drawback of this process is the production of concentrated waste streams that necessitate further processing. We report a novel approach termed catalytic capacitive deionization (CCDI) that combines selective heterogeneous catalysis with CDI to significantly reduce undesired waste products. In CCDI, porous electrodes containing catalytic nanoparticles are used to electrostatically adsorb and degrade ionic contaminants to less toxic byproducts. We demonstrate CCDI through the removal and reduction of nitrate in water toward innocuous nitrogen gas rather than thermodynamically favorable ammonium. A 50 mg-N/L nitrate was continuously fed to the CCDI reactor at 1 mL/min and adsorbed and treated through 20-min adsorption/catalytic cycles, resulting in an effluent containing 2 mg-N/L nitrate and trace amounts of byproducts, below maximum concentration levels defined for drinking purposes. At a cell potential of 1.5 V, the CCDI system removed 92% of the nitrate in the feed, and 91% of the adsorbed nitrate was selectively transformed to produce innocuous N₂. This work demonstrates that CCDI can potentially be used as a novel approach to treat a wide range of aqueous ionic contaminants, significantly advancing the next generation of CDI systems.

中文翻译：

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用于吸附和还原硝酸盐的催化电容去离子

电容去离子 (CDI) 是一种环境修复技术，可以去除水性离子污染物，但该过程的主要缺点是产生需要进一步处理的浓缩废物流。我们报告了一种称为催化电容去离子 (CCDI) 的新方法，该方法将选择性多相催化与 CDI 相结合，以显着减少不需要的废物。在 CCDI 中，包含催化纳米粒子的多孔电极用于静电吸附离子污染物并将其降解为毒性较低的副产物。我们通过将水中的硝酸盐去除和还原为无害的氮气而不是热力学有利的铵来证明 CCDI。将 50 mg-N/L 硝酸盐以 1 mL/min 的速度连续送入 CCDI 反应器，并通过 20 分钟的吸附/催化循环进行吸附和处理，产生含有 2 mg-N/L 硝酸盐和痕量副产物的流出液，低于为饮酒目的定义的最大浓度水平。在 1.5 V 的电池电位下，CCDI 系统去除了饲料中 92% 的硝酸盐，91% 的吸附硝酸盐被选择性转化以产生无害的 N₂ . 这项工作表明 CCDI 有可能用作处理各种水性离子污染物的新方法，显着推进下一代 CDI 系统。