This study investigates the catalytic potential of anionic MnO2 nanosheets (Mn), a cationic covalent organic Framework (COF), and their composites (CM, C2M, and CM2) with varying Mn weight percentages for arsenic removal from groundwater. The catalysts were used as activators of sodium sulfite (SS) under light conditions, enabling the pre-oxidation of arsenic (III) (As3) to arsenic(V) (As5), followed by the adsorption of As5 for complete arsenic removal from water. The Mn-COF-SS systems (C2M, CM, CM2) exhibited superior performance compared to Mn and COF alone, highlighting the dual functionality of the composites as both oxidizing agents and effective adsorbents for arsenic species. Among the composites, CM2 with 32 wt% Mn demonstrates exceptional efficiency, achieving 99.99 % arsenic removal within 30 min. The sorption process in a batch reactor was pH-dependent, with sulfate radicals (SO4-) and electrostatic interactions playing key roles in As3 oxidation and As5 removal, respectively. The pseudo-second-order kinetic model was found to be the dominant model for the sorption process, and the sorption process was compatible with the Freundlich isotherm model, which indicates a multilayer adsorption process of arsenic species on CM2. The practical application of CM2 in a fixed-bed reactor showed its high efficiency for arsenic removal, achieving the contaminant level below 10 ppb as recommended by WHO. This project highlights the potential of CM2 as an effective catalyst for arsenic removal, offering a promising approach to mitigating arsenic contamination in water sources.

中文翻译：

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制备有机/无机反应复合材料，以快速去除地下水系统中的砷


本研究研究了阴离子 MnO2 纳米片 （Mn）、阳离子共价有机框架 （COF） 及其具有不同 Mn 重量百分比的复合材料 （CM、C2M 和 CM2） 从地下水中去除砷的催化潜力。催化剂在光照条件下用作亚硫酸钠 （SS） 的活化剂，使砷 （III） （As3） 预氧化为砷 （V） （As5），然后吸附 As5 以完全去除水中的砷。与单独的 Mn 和 COF 相比，Mn-COF-SS 系统（C2M、CM、CM2）表现出优异的性能，突出了复合材料作为氧化剂和砷物质有效吸附剂的双重功能。在复合材料中，Mn 含量为 32 wt% 的 CM2 表现出卓越的效率，可在 30 分钟内实现 99.99% 的砷去除率。间歇式反应器中的吸附过程与 pH 值有关，硫酸根自由基 （SO4-） 和静电相互作用分别在 As3 氧化和 As5 去除中起关键作用。发现准二级动力学模型是吸附过程的主要模型，吸附过程与 Freundlich 等温线模型兼容，表明砷物质在 CM2 上的多层吸附过程。CM2 在固定床反应器中的实际应用表明，其除砷效率高，达到了 WHO 建议的低于 10 ppb 的污染物水平。该项目强调了 CM2 作为有效除砷催化剂的潜力，为减轻水源中的砷污染提供了一种有前途的方法。