Heavy metal pollution threatens aquatic systems worldwide, and mining activities are an important pollution source. Currently, the treatment of polluted water using a cost-effective technology that can purify multiple pollutants and is sustainable, environmentally friendly, and simple is a major challenge. The in situ preparation of Mg–Al layered double hydroxides (LDHs) and the concurrent treatment of Zn, Cd, and Pb from mining wastewater are important for preventing multiple steps and increasing adsorption sites. This study focused on mining wastewater containing high concentrations of Mg²⁺ and Al³⁺, with anion chemistry controlled by SO₄²⁻, which facilitates the formation of LDHs. The required amounts of Mg²⁺ and Al³⁺ ions were added to the wastewater, and the conditions for the creation of Mg–Al LDHs were controlled. The heavy metals in the experimental wastewater were effectively removed after the treatment via Mg–Al LDH formation. The X-ray diffraction of the post-treatment products suggested the formation of Mg–Al LDHs. The Mg/Al molar ratio (2.3:1) in the product approached the initial ratio (2:1), which meets the general limits of Mg–Al LDH formation. Scanning electron microscopy revealed that the products had a sheetlike stacked morphology, providing evidence for the formation of Mg–Al LDHs. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that SO₄²⁻ might be the intercalated anion in the Mg–Al LDH layers. Consequently, SO₄²⁻ was removed from the mining wastewater, as it was captured between the LDH layers during the formation reaction of Mg–Al LDHs.

中文翻译：

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Mg-Al层状双氢氧化物的形成处理采矿废水中Zn，Cd和Pb的简便方法

重金属污染威胁着全世界的水生系统，采矿活动是重要的污染源。当前，使用可净化多种污染物并具有可持续性，环境友好性和简单性的高性价比技术来处理污水是一项重大挑战。Mg-Al层状双氢氧化物（LDHs）的原位制备以及采矿废水中Zn，Cd和Pb的同时处理对于防止多步操作和增加吸附位点很重要。这项研究的重点是采矿废水中含有高浓度的Mg ²⁺和Al ³⁺，其阴离子化学由SO ₄ ^2-控制，这有利于LDH的形成。所需的Mg ²⁺和Al量向废水中添加了³⁺离子，并控制了生成Mg-Al LDH的条件。处理后的废水中的重金属通过Mg-Al LDH的形成得以有效去除。后处理产物的X射线衍射表明形成了Mg–Al LDHs。产品中的Mg / Al摩尔比（2.3：1）接近初始比率（2：1），符合Mg-Al LDH形成的一般限制。扫描电子显微镜显示，产品具有薄片状的堆叠形态，为形成Mg-Al LDH提供了证据。傅里叶变换红外光谱和X射线光电子能谱表明SO ₄ ^2-可能是Mg-Al LDH层中的嵌入阴离子。因此，SO ₄ ²⁻ 从采矿废水中去除，因为它是在Mg-Al LDH的形成反应过程中在LDH层之间捕获的。