Phosphonate is becoming a global interest and concern owing to its environment risk and potential value. Degradation of phosphonate into phosphate followed by the recovery is regarded as a promising strategy to control phosphonate pollution, relieve phosphorus crisis, and promote phosphorus cycle. Given these objectives, an anion-membrane-coated-electrode (A-MCE) doped with Fe-Co based carbon catalyst and cation-membrane-coated-electrode (C-MCE) doped with carbon-based catalyst were prepared as catalytic electrodes, and a novel electrocatalytic capacitive deionization (E-CDI) was developed. During charging process, phosphonate was enriched around A-MCE surface based on electrostatic attraction, ligand exchange, and hydrogen bond. Meanwhile, Fe and Co were self-oxidized into Fe and Co, forming a complex with enriched phosphonate and enabling an intramolecular electron transfer process for phosphonate degradation. Additionally, benefiting from the stable dissolved oxygen and high oxygen reduction reaction activity of C-MCE, hydrogen peroxide accumulated in E-CDI (158 μM) and thus hydroxyl radicals (·OH) were generated by activation. E-CDI provided an ideal platform for the effective reaction between ·OH and phosphonate, avoiding the loss of ·OH and triggering selective degradation of most phosphonate. After charging for 70 min, approximately 89.9% of phosphonate was degraded into phosphate, and phosphate was subsequently adsorbed by A-MCE. Results also showed that phosphonate degradation was highly dependent on solution pH and voltage, and was insignificantly affected by electrolyte concentration. Compared to traditional advanced oxidation processes, E-CDI exhibited a higher degradation efficiency, lower cost, and less sensitive to co-existed ions in treating simulated wastewaters. Self-enhanced and selective degradation of phosphonate, and in-situ phosphate adsorption were simultaneously achieved for the first time by a E-CDI system, showing high promise in treating organic-containing saline wastewaters.

中文翻译：

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用于选择性磷酸盐降解的新型电催化电容去离子催化电极：性能和机制

由于其环境风险和潜在价值，磷酸盐正成为全球关注的焦点。膦酸盐降解为磷酸盐并回收被认为是控制膦酸盐污染、缓解磷危机、促进磷循环的一种有前景的策略。鉴于这些目标，制备了掺杂有Fe-Co基碳催化剂的阴离子膜涂层电极（A-MCE）和掺杂有碳基催化剂的阳离子膜涂层电极（C-MCE）作为催化电极，并开发了一种新型电催化电容去离子（E-CDI）。在充电过程中，膦酸盐基于静电吸引、配体交换和氢键富集在A-MCE表面周围。同时，Fe和Co自氧化成Fe和Co，与富集的膦酸盐形成络合物，并实现分子内电子转移过程以实现膦酸盐降解。此外，得益于C-MCE稳定的溶解氧和高氧还原反应活性，过氧化氢在E-CDI（158 μM）中积累，从而活化产生羟基自由基（·OH）。 E-CDI为·OH和膦酸酯之间的有效反应提供了理想的平台，避免了·OH的损失并引发大多数膦酸酯的选择性降解。充电70分钟后，约89.9%的膦酸盐降解为磷酸盐，随后磷酸盐被A-MCE吸附。结果还表明，膦酸盐的降解高度依赖于溶液的 pH 值和电压，并且受电解质浓度的影响不显着。与传统的高级氧化工艺相比，E-CDI在处理模拟废水时表现出更高的降解效率、更低的成本、对共存离子的敏感性更低。 E-CDI系统首次同时实现了磷酸盐的自我增强和选择性降解以及磷酸盐的原位吸附，在处理含有机物含盐废水方面显示出良好的前景。