Abstract:

As a kind of refractory wastewater，the effective treatment of wastewater containing heavy metals was a research hotspot in the field of environment. Layered double hydroxides（LDHs） is a kind of heavy metal adsorbent with high application potential due to its large specific surface area，simple preparation and environmental friendliness. Hollow layered double hydroxides（LDHs-H） with more adsorption sites were prepared and heavy metal ions such as Cu²⁺，Pb²⁺，Zn²⁺ and Ni²⁺ were selected. The effects of initial heavy metal ion concentration，adsorption time，solution pH and competitive ions on the adsorption of heavy metal ions by LDHs-H were investigated. The results showed that the adsorption isotherms of LDHs-H for Cu²⁺ and Pb²⁺ well fitted with Freundlich model，and Langmuir model well described the isotherms of Zn²⁺ and Ni²⁺. Kinetic data of the adsorption process of four heavy metals fitted pseudo-second-order model well. Hydroxyl groups on LDHs-H reacting with Cu²⁺ and Pb²⁺ to form precipitation was the main way to remove Cu²⁺ and Pb²⁺，and substitution and crystal growth with Zn²⁺ and Ni²⁺ were the main mechanism for LDHs-H to fix Zn²⁺ and Ni²⁺. Coexisting ions experiments showed that common ions in wastewater could not affect the adsorption effect of LDHs-H on heavy metals，and LDHs-H had good adsorption effect on heavy metals in neutral conditions.

Key words: hollow layered double hydroxides, heavy metals, wastewater treatment, adsorption mechanism

摘要：

重金属废水是一类难处理的废水，对其进行有效处理一直是环境领域的研究热点。类水滑石（LDHs）因比表面积大、制备简单、环境友好等特性，成为一类具有较高应用潜力的重金属吸附剂。制备了具有更多吸附位点的空心类水滑石（LDHs-H），选取重金属离子Cu²⁺、Pb²⁺、Zn²⁺和Ni²⁺作为研究对象，探究了初始重金属离子浓度、吸附时间、溶液pH和竞争离子等因素对LDHs-H吸附重金属离子的影响。结果表明，LDHs-H对Cu²⁺和Pb²⁺的等温吸附数据较好地拟合了Freundlich等温模型，对Zn²⁺和Ni²⁺的等温吸附数据较好地拟合了Langmuir等温模型。准二级动力学模型较好地描述了LDHs-H对4种重金属离子的动力学吸附过程。LDHs-H层板上的羟基与Cu²⁺和Pb²⁺反应生成沉淀是Cu²⁺和Pb²⁺去除的主要方式，与Zn²⁺和Ni²⁺发生同晶替代和晶体生长是LDHs-H吸附Zn²⁺和Ni²⁺的主要机理。共存离子实验证明废水中常见离子几乎均不会影响LDHs-H对重金属离子的吸附，且中性条件下LDHs-H对重金属离子具有较好的吸附效果。

关键词: 空心类水滑石, 重金属, 废水处理, 吸附机理

CLC Number: 

• TQ424