Roxarsone (ROX) is an emerging arsenic pollutant due to its potential degradation into highly toxic inorganic arsenic species in the environment. Adsorbents which can capture ROX with both high capacity and affinity are urgently needed. Herein, a nanocomposite of nano-Fe₃O₄ and three-dimensional graphene (Fe₃O₄@RGO) was designed, aiming to simultaneously attract arsenate and benzene groups in ROX. Characterization of the nanocomposite revealed that Fe₃O₄ nanoparticles (20–50 nm) with exposed (400) planes were highly dispersed on the graphene support. Adsorption experiments showed that Fe₃O₄@RGO had higher adsorption capacity, affinity, and adsorption rate towards ROX than pristine materials and efficiently removed ROX from both simulated natural and waste waters. The adsorption mechanism was confirmed as a synergetic interaction of As–Fe coordination, hydrogen bonding and π–π interaction. X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) results suggested that the As–Fe complexes and hydrogen bonds between Fe₃O₄@RGO and ROX were stronger than those in pristine nano-Fe₃O₄, due to the greater number of surface hydroxyls and shorter As–Fe atomic distance in Fe₃O₄@RGO. The π–π interaction between ROX and the graphene part in Fe₃O₄@RGO was also enhanced. This study provided a novel idea for designing materials to remove pollutants with both inorganic and organic moieties, such as phenylarsonic acid compounds, from water.

中文翻译：

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Fe ₃ O ₄ @ 3D石墨烯纳米复合材料增强去除洛沙酮的协同吸附和机理

Roxarsone（ROX）是一种新兴的砷污染物，因为它有可能在环境中降解为剧毒的无机砷。迫切需要能够以高容量和亲和力捕获ROX的吸附剂。在此，设计了一种纳米Fe ₃ O ₄和三维石墨烯（Fe ₃ O ₄ @RGO）的纳米复合材料，旨在同时吸引ROX中的砷酸根和苯基。纳米复合材料的表征表明，具有暴露的（400）平面的Fe ₃ O ₄纳米颗粒（20–50 nm）高度分散在石墨烯载体上。吸附实验表明Fe ₃ O ₄与原始材料相比，@ RGO对ROX的吸附能力，亲和力和吸附速率更高，并且可以有效地从模拟天然水和废水中去除ROX。吸附机理被证实为As-Fe配位，氢键和π-π相互作用的协同相互作用。X射线光电子能谱（XPS）和扩展的X射线吸收精细结构（EXAFS）的结果表明，Fe ₃ O ₄ @RGO和ROX之间的As-Fe配合物和氢键比原始的纳米Fe ₃ O中的要强。_{如图4所示}，由于在Fe ₃ O ₄ @RGO中存在更多的表面羟基和较短的As-Fe原子距离。ROX与Fe中石墨烯部分之间的π–π相互作用₃ O ₄ @RGO也得到了增强。这项研究为设计材料从水中去除无机和有机部分的污染物（例如苯ar酸化合物）提供了新思路。