Oxalic acid-modified ball-milled zero-valent iron (OA-ZVIbm) was employed to activate sodium chlorite (ClO2-) for the removal of norfloxacin (NOR). The complete removal of 20 mg/L NOR was achieved within 60 min by the OA-ZVIbm/ClO2- process. Compared with the ZVIbm/ClO2- process which was the ball-milled zero-valent iron (ZVIbm) activate sodium chlorite, the reaction activity of the OA-ZVIbm/ClO2- process was increased by 102.6 times. Through scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical testing, and density functional theory (DFT) calculations, which has been confirmed that the introduction of oxalic acid can significantly increase the surface Fe(II) content of OA-ZVIbm, and accelerate the electron transfer rate of iron nuclei, thereby improve the efficiency of ClO2- activation for the removal of NOR. The role of various active species in NOR removal, which were •O2-, 1O2, Fe(IV), ClO2, and •OH, was elucidated through free radical quenching experiments, electron paramagnetic resonance (EPR) spectroscopy, and quantitative detection of active species. These active species all participated in the reaction, while •O2- played a dominant role in the reaction because it could transform into other active species, such as (•OH, 1O2). Inorganic anions and natural organic matter have no significant effect on the removal of NOR in the OA-ZVIbm/ClO2- process. The protonation of oxalic acid ensured its good pH applicability range (pH = 2–11), thus exhibiting excellent performance in NOR removal in real water bodies. This further demonstrates that OA-ZVIbm prepared by oxalic acid ball milling modification is an efficient ClO2- activator, offering promising prospects for antibiotic removal technology.

中文翻译：

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通过具有丰富表面 Fe（II） 位点的草酸零价铁对诺氟沙星的去除，激活了亚氯酸盐


草酸改性球磨零价铁 （OA-ZVIbm） 用于活化亚氯酸钠 （ClO2-） 以去除诺氟沙星 （NOR）。通过 OA-ZVIbm/ClO2- 工艺在 60 分钟内完全去除 20 mg/L NOR。与球磨零价铁 （ZVIbm） 活化亚氯酸钠的 ZVIbm/ClO2- 工艺相比，OA-ZVIbm/ClO2- 工艺的反应活性提高了 102.6 倍。通过扫描电子显微镜 （SEM）、X 射线光电子能谱 （XPS）、电化学测试和密度泛函理论 （DFT） 计算，证实草酸的引入可以显着增加 OA-ZVIbm 的表面 Fe（II） 含量，并加快铁核的电子转移速率，从而提高 ClO2-活化去除 NOR 的效率。通过自由基猝灭实验、电子顺磁共振 （EPR） 波谱和活性物质的定量检测，阐明了 •O2-、1O2、Fe（IV）、ClO2 和 •OH 等各种活性物质在 NOR 去除中的作用。这些活性物质都参与了反应，而 •O2- 在反应中起主导作用，因为它可以转化为其他活性物质，例如 （•OH， 1O2）。无机阴离子和天然有机物对 OA-ZVIbm/ClO2- 过程中 NOR 的去除没有显着影响。草酸的质子化确保了其良好的 pH 适用性范围 （pH = 2–11），因此在实际水体中表现出优异的 NOR 去除性能。这进一步表明，草酸球磨改性制备的 OA-ZVIbm 是一种高效的 ClO2 激活剂，为抗生素去除技术提供了广阔的前景。