天然沸石对模拟尾矿渗滤液中重金属离子的静、动态吸附研究

Study on the Static and Dynamic Adsorption of Heavy Metal Ions in Simulated Tailings Leachate by Natural Zeolite

  • 摘要: 沸石具有良好的吸附性能和离子交换特性,对去除水中的重金属离子具有廉价、高效的优点。利用天然沸石矿物作为吸附材料,探讨了在不同条件下对干扰分选过程的多种重金属离子的去除效果和去除机制,研究了其在静、动态条件下去除模拟尾矿渗滤液中重金属离子的性能和机理。单一重金属离子静态吸附实验结果表明,沸石对Pb2+、Cu2+、Mn2+、Zn2+均有较好的去除效果,对4种重金属离子的吸附能力大小为Pb2+ > Cu2+ > Zn2+ > Mn2+。混合离子静态吸附实验结果表明,在任意初始质量浓度下,Pb2+在沸石上的吸附量均远大于Cu2+、Zn2+和Mn2+。4种离子的吸附过程均符合Langmuir等温模型,属于单分子层吸附,准二级动力学模型能较好地描述沸石吸附4种重金属离子的过程,沸石在离子交换、表面静电和断键络合的共同作用下去除重金属离子,由于存在竞争吸附,沸石对相同价态不同阳离子的吸附能力存在较大差异,这主要受不同阳离子的水合半径的影响。动态条件下沸石对Cu2+、Mn2+、Pb2+、Zn2+ 的去除分别在102 h、64 h、900 h和78 h达到平衡,沸石的有效工作时间较长,可作为渗透反应格栅 (PRB) 的介质材料用于多金属矿尾矿渗滤液污染地下水的原位修复,具有良好的社会和经济效益。

     

    Abstract: Mineral processing wastewater contains a large amount of heavy metal ions. If not properly treated, it will pollute water sources and soil, and endanger human health. Zeolites possess excellent adsorption properties and ion exchange characteristics, making them cost−effective and highly efficient in removing heavy metal ions from water. This study utilizes natural zeolite minerals as adsorption materials to investigate the removal efficiency and mechanisms of various heavy metal ions in the interference sorting process under different conditions. It discusses the removal effect and mechanism of zeolite and its modified materials on the heavy metal ions that interfere with the separation process under different conditions. The performance and mechanism of removing heavy metal ions in simulated tailings leachate under static and dynamic conditions were studied. The results of the static adsorption experiments on single heavy metal ions indicate that zeolite has good removal efficiency for Cu2+, Pb2+, Zn2+, and Mn2+, with the adsorption capacity ranking as Pb2+ > Cu2+ > Zn2+ > Mn2+. The adsorption process of four types of ions all conform to the Langmuir isotherm model, which is a monolayer adsorption. The pseudo-second order kinetic model can describe the process of zeolite adsorbing four kinds of heavy metal ions well. Zeolite removes heavy metal ions through the combined action of ion exchange and surface electrostatics. Due to the existence of competitive adsorption, the adsorption capacity of zeolite to different cations with the same valence state is quite different. This is mainly influenced by the hydration radius of the different cations. Under dynamic conditions, the removal of Cu2+, Mn2+, Pb2+, and Zn2+ by zeolite reaches equilibrium at 102 h, 64 h, 900 h, and 78 h, respectively. The effective working time of zeolite is longer, and it can be used as the medium material of permeation reaction grid (PRB) It is used for in−situ remediation of groundwater polluted by leachate from polymetallic mine tailings, and has good social and economic benefits.

     

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