The use of electrochemical advanced oxidation process (EAOP) for treating NH₄⁺-rich wastewater via reactive halogen species offers a promising alternative to biological methods but faces challenges in strong acid due to poor NH₄⁺ oxidation kinetics. Herein, we identify the strong solvation of NH₄⁺ as the key limiting factor, where surrounding H₂O molecules form a protective shield that hinders oxidative species. To address this, low-frequency sonication (LFS, e.g., 40 kHz) was introduced, disrupting the solvation environment through cavitation and enhancing NH₄⁺ exposure to oxidative species. At pH 2, electrolysis alone exhibited only 8.0–28.8% NH₄⁺ oxidation efficiency within 2.5 h, while this value significantly improved (60.73–100%) in the LFS-Cl/EAOP systems and reached 100% in the LFS-Br/EAOP systems. The LFS-Cl/EAOP systems showed strong dependence on anode materials, with boron-doped diamond (BDD) and PbO₂ outperforming mixed metal oxides (MMO) and Pt; in contrast, the LFS-Br/EAOP systems achieved high NH₄⁺ removal regardless of anode type. It is further revealed that bromate formation was suppressed by rapid HBrO consumption and cathodic reduction. Moreover, the feasibility of complete NH₄⁺ elimination and acid solution regeneration for NH₃ adsorption via LFS-Br/EAOP was demonstrated, highlighting its potential for practical application.

中文翻译：

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通过低频超声处理对强酸中的铵进行高效电化学氧化：铵脱溶剂化的作用

使用电化学高级氧化工艺 （EAOP） 通过反应性卤素物质处理富含 NH₄⁺ 的废水，为生物方法提供了一种很有前途的替代方案，但由于 NH₄⁺ 氧化动力学较差，在强酸中面临挑战。在此，我们确定 NH₄⁺ 的强溶剂化是关键限制因子，其中周围的 H₂O 分子形成阻碍氧化物质的保护屏障。为了解决这个问题，引入了低频超声处理（LFS，例如 40 kHz），通过空化破坏溶剂化环境并增强 NH₄⁺ 对氧化物质的暴露。在 pH 值为 2 时，单独电解在 2.5 小时内仅表现出 8.0-28.8% 的 NH₄⁺ 氧化效率，而该值在 LFS-Cl/EAOP 系统中显著提高 （60.73-100%），在 LFS-Br/EAOP 系统中达到 100%。LFS-Cl/EAOP 系统表现出对负极材料的强烈依赖性，硼掺杂金刚石 （BDD） 和 PbO₂ 的性能优于混合金属氧化物 （MMO） 和 Pt;相比之下，LFS-Br/EAOP 系统无论阳极类型如何，都能实现高 NH₄⁺ 去除率。进一步揭示溴酸盐的形成被快速 HBrO 消耗和阴极还原所抑制。此外，还证明了通过 LFS-Br/EAOP 完全消除 NH₄⁺ 和酸溶液再生用于 NH₃ 吸附的可行性，突出了其实际应用的潜力。