Institute of Hydrogeology & Environmental Geology, CAGS, Shijiazhuang, 050061, China; Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes, Xiamen, 361021, China.
Institute of Hydrogeology & Environmental Geology, CAGS, Shijiazhuang, 050061, China; Key Laboratory of Groundwater Remediation of Hebei Province and China Geological Survey, Shijiazhuang, 050061, China.
Environ Pollut. 2022 Nov 15;313:120155. doi: 10.1016/j.envpol.2022.120155. Epub 2022 Sep 18.
Iron-based materials have been widely investigated because of their high surface reactivity, which has shown potential for the remediation of metal(loid)s in groundwater. However, the disadvantages of structural stability and economic feasibility always limit their application in permeable reactive barrier (PRB) technology. In this study, zeolite-supported iron particles (Zeo-Fe) were synthesized by an innovative low-cost physical preparation method that is suitable for mass production. The removal efficiency and mechanism of typical metal(loid)s (Pb, Cd, Cr and As) were subsequently investigated using various kinetic and equilibrium models and characterization methods. The results of scanning electron microscopy and energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) confirmed that zero valent iron (Fe) and oxidation product (FeO) were successfully loaded and efficiently dispersed on zeolite. The synthesized Zeo-Fe exhibited excellent adsorption and redox capacities for the cations Pb, Cd and anions Cr, As. The increase in the pH resulting from Fe corrosion also enhanced the precipitation of Fe-metal(loid)s. The maximum removal capacity for Pb, Cd, Cr and As was up to 70.00, 9.12, 2.35 and 0.36 mg/g, respectively. The removal processes were well described by the pseudo-second-order kinetic model for Pb and Cd, Lagergren pseudo first-order kinetics model for As and double phase first order kinetics model l for Cr. Cr was rapidly reduced to Cr by the Fe stabilized on Zeo-Fe, and the oxidation of As to As was attributed to the FeFe oxidation process at the interface over time, which was further demonstrated by the mineral phase and element valence analyses of reacted Zeo-Fe. The removal mechanism for metal(loid)s was a combination of physical and chemical processes, including adsorption, co-precipitation and reduction-oxidation. Conclusively, Zeo-Fe has been shown to have potential as an effective and economical material for removing various metal(loid)s used in PRB.
铁基材料因其高表面反应活性而被广泛研究，这显示了其在地下水金属（类）修复方面的潜力。然而，结构稳定性和经济可行性的缺点始终限制了它们在可渗透反应屏障（PRB）技术中的应用。在本研究中，通过一种创新的低成本物理制备方法合成了沸石负载铁颗粒（Zeo-Fe），该方法适合大规模生产。随后使用各种动力学和平衡模型以及表征方法研究了典型金属（类）（Pb、Cd、Cr 和 As）的去除效率和机制。扫描电子显微镜和能谱（SEM-EDS）、X 射线衍射（XRD）、X 射线光电子能谱（XPS）和透射电子显微镜（TEM）的结果证实，零价铁（Fe）和氧化产物（FeO）成功负载并在沸石上有效分散。合成的 Zeo-Fe 对阳离子 Pb、Cd 和阴离子 Cr、As 表现出优异的吸附和氧化还原能力。Fe 腐蚀导致的 pH 值升高也增强了 Fe-金属（类）的沉淀。Pb、Cd、Cr 和 As 的最大去除容量分别高达 70.00、9.12、2.35 和 0.36mg/g。Pb 和 Cd 的去除过程很好地符合准二级动力学模型，As 的去除过程符合 Lagergren 伪一级动力学模型，Cr 的去除过程符合双相一级动力学模型。Cr 被固定在 Zeo-Fe 上的 Fe 迅速还原为 Cr，而随着时间的推移，As 被氧化为 As 归因于界面处的 Fe-Fe 氧化过程，这进一步通过反应后的 Zeo-Fe 的矿物相和元素价态分析得到证实。金属（类）的去除机制是物理和化学过程的结合，包括吸附、共沉淀和还原-氧化。总之，Zeo-Fe 已被证明是一种用于 PRB 中去除各种金属（类）的有效且经济的材料。
