School of Ecology and Environmental Science, Shanghai Key Laboratory for Urban Ecological Process and Eco-Restoration in East China Normal University, and Institute of Eco-Chongming, Shanghai 200062, China.
School of Environmental Science and Engineering, Tongji University, Shanghai, China.
J Colloid Interface Sci. 2019 Oct 15;554:692-704. doi: 10.1016/j.jcis.2019.07.046. Epub 2019 Jul 17.
Arsenic species are regarded as typical water pollutants due to their toxicity. The chemical structures of arsenic species greatly influence their migration and transformation in the environment. Metal-organic frameworks (MOFs) are used as reliable adsorbents to control arsenic contamination, so it is urgently needed to study the effect of chemical structure of arsenic species during adsorption process. The adsorption behaviors of arsenate (As(V)) and its organic forms such as roxarsone (ROX), p-arsanilic acid (p-ASA) and dimethyl arsenate (DMA) by MIL-101(Fe), a type of highly porosity iron-based MOFs in aqueous environment were detailed investigated. The adsorption kinetics of those arsenic species on MIL-101(Fe) is rapid followed with pseudo-second-order kinetic model. MIL-101(Fe) exhibits excellent adsorption capacities for As(V), ROX, p-ASA and DMA with maximum adsorption capacities of 232.98, 507.97, 379.65 and 158.94 mg g, respectively. The formed FeOAs inner-sphere coordination between arsenic species and the incomplete-coordinated cationic Fe in the MIL-101(Fe) cluster is the primary adsorption mechanism based on FTIR and XPS analysis. Substituent aromatic units in ROX and p-ASA strengthen the adsorption on MIL-101(Fe) through hydrogen bonds and π-π stacking interaction, resulting in higher adsorption capacities far beyond that of As(V) and DMA. The reusability of MIL-101(Fe) is limited by the strong FeOAs coordination. These results confirm MIL-101(Fe) a reliable adsorbent to control the aqueous arsenic species contamination and emphasize the significant role of the chemical structure of arsenic speciation on adsorption performances of MOFs.
砷物种因其毒性而被视为典型的水污染物质。砷物种的化学结构极大地影响了它们在环境中的迁移和转化。金属有机骨架（MOFs）被用作控制砷污染的可靠吸附剂，因此迫切需要研究吸附过程中砷物种化学结构的影响。详细研究了在水溶液中，高度多孔铁基 MOFs 型 MIL-101(Fe)对砷酸盐（As(V)）及其有机形式如罗硝唑（ROX）、对氨基苯砷酸（p-ASA）和二甲基砷酸（DMA）的吸附行为。这些砷物种在 MIL-101(Fe)上的吸附动力学很快，符合拟二级动力学模型。MIL-101(Fe)对 As(V)、ROX、p-ASA 和 DMA 具有优异的吸附能力，最大吸附容量分别为 232.98、507.97、379.65 和 158.94mg/g。基于 FTIR 和 XPS 分析，砷物种与 MIL-101(Fe) 中不完全配位的阳离子 Fe 之间形成的 FeOAs 内球配位是主要的吸附机制。ROX 和 p-ASA 中的取代芳香单元通过氢键和π-π堆积相互作用增强了对 MIL-101(Fe)的吸附，导致吸附容量远高于 As(V)和 DMA。MIL-101(Fe)的可重复使用性受到强 FeOAs 配位的限制。这些结果证实了 MIL-101(Fe)是一种可靠的吸附剂，可以控制水中砷物种的污染，并强调了砷形态的化学结构对 MOFs 吸附性能的重要作用。
