Removal of heavy metal ions from aqueous solutions with multi-walled carbon nanotubes: Kinetic and thermodynamic studies
Removal of heavy metal ions from aqueous solutions with multi-walled carbon nanotubes: Kinetic and thermodynamic studies
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DOI：
10.1007/s13762-012-0127-6
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发表时间：
2013-10
影响因子：
3.1
通讯作者：
M. Abdel Salam
中科院分区：
文献类型：
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作者：
M. Abdel Salam
多壁碳纳米管被成功地用于从水溶液中去除铜（II）、铅（II）、镉（II）和锌（II）。结果表明，由于吸附过程的吸热性质，吸附%随着溶液温度的升高而增加。采用分数幂函数模型、Lagergren准一级动力学模型、准二级动力学模型和Elovich动力学模型对多壁碳纳米管吸附Cd（II）、Pb（II）、Cu（II）和Zn（II）的动力学进行了分析，结果表明：多壁碳纳米管对重金属离子的吸附为准二级动力学过程，吸附量随溶液温度的升高而增大。从吸附容量评估碳纳米管对金属离子的结合，发现其遵循以下顺序：铜（II）>铅（II）>锌（II）>镉（II）。热力学参数的计算结果表明，所有金属离子的吸附自由能均为负值，表明吸附过程具有自发性，且这种自发性随溶液温度的升高而增强。熵值的变化是正的，表明由于重金属离子从水溶液到碳纳米管表面的物理吸附而增加了随机性。虽然多壁碳纳米管对重金属离子的吸附焓值均为正值，但自由能均为负值，且吸附是自发的，表明多壁碳纳米管对重金属离子的吸附是一个熵驱动的过程。
Multi-walled carbon nanotubes were used successfully for the removal of Copper(II), Lead(II), Cadmium(II), and Zinc(II) from aqueous solution. The results showed that the % adsorption increased by raising the solution temperature due to the endothermic nature of the adsorption process. The kinetics of Cadmium(II), Lead(II), Copper(II), and Zinc(II) adsorption on Multi-walled carbon nanotubes were analyzed using the fraction power function model, Lagergren pseudo-first-order, pseudo-second-order, and Elovich models, and the results showed that the adsorption of heavy metal ions was a pseudo-second-order process, and the adsorption capacity increased with increasing solution temperature. The binding of the metal ions by the carbon nanotubes was evaluated from the adsorption capacities and was found to follow the following order: Copper(II) > Lead(II) > Zinc(II) > Cadmium(II). The thermodynamics parameters were calculated, and the results showed that the values of the free energies were negative for all metals ions, which indicated the spontaneity of the adsorption process, and this spontaneity increased by raising the solution temperature. The change in entropy values were positives, indicating the increase in randomness due to the physical adsorption of heavy metal ions from the aqueous solution to the carbon nanotubes’ surface. Although the enthalpy values were positive for all metal ions, the free energies were negative, and the adsorption was spontaneous, which indicates that the heavy metal adsorption of Multi-walled carbon nanotubes was an entropy-driving process.