天然磁铁矿和商用Fe_3O_4修复Hg(Ⅱ)污染地下水的模拟研究

Simulating Remediation of Hg(Ⅱ)-Contaminated Groundwater Using Natural Magnetite and Commercial Fe_3O_4

目前汞污染地下水修复面临很大的技术和成本挑战,亟需发展修复效果好、经济效益性高的汞污染地下水修复技术和修复材料。通过批量实验和光谱分析探究了天然磁铁矿和商用Fe_3O_4对Hg(Ⅱ)的去除效率和去除机制,并分析了两种材料对模拟地下水中Hg(Ⅱ)的吸附和脱附行为。结果表明,天然磁铁矿和商用Fe_3O_4对Hg(Ⅱ)的去除受pH、Hg(Ⅱ)初始浓度、Cl-等因素的影响;二者对Hg(Ⅱ)的去除均符合准二级动力学模型和Freundlich模型;天然磁铁矿对Hg(Ⅱ)的去除机制主要是羟基络合与物理吸附,而商用Fe_3O_4对Hg(Ⅱ)的去除主要是化学还原与物理吸附。二者对模拟地下水中Hg(Ⅱ)的去除率分别达90%和95%,具有修复Hg(Ⅱ)污染地下水的应用潜力。

Currently, remediation of Hg（II）-contaminated groundwater is technically challenging and very costly. It is urgently needed to develop effective and cost-effective technology and material to remediate Hg（Ⅱ）-contaminated groundwater. The efficiency and mechanism of Hg（Ⅱ） removal from groundwater by two types of iron-based sorbents, natural magnetite and commercial Fe304, were investigated in this study. Hg（Ⅱ） sorption and desorption on magnetites were also investigated in simulated groundwater. The results showed that both natural magnetite and commercial Fe304 removed Hg（Ⅱ） effectively, and Hg（Ⅱ） removal efficiency was influenced by initial pH, initialHg（Ⅱ） concentration, coexisting ion of CI-, and so on. Sorption kinetic data were well fitted to the pseudo-second-order model. The sorption isotherm could be described by the Freundlich model. The sorption of Hg（Ⅱ） on natural magnetite was mainly due to the complexation between Hg（Ⅱ） and surface hydroxyl groups and physisorption, while the sorption of Hg（Ⅱ） on commercial Fe304 was largely due to the reduction of Hg（Ⅱ）by Hg（Ⅱ） in Fe304 and physisorption. Hg（Ⅱ）removal from simulated groundwater by natural magnetite and commercial Fe304 were nearly 90% and 95%, respectively, demonstrating the application potential of both sorbents in remediating Hg（Ⅱ）-contaminated groundwater.