Removal of Heavy Metal Ions Using a Functionalized Single-Walled Carbon Nanotube: A Molecular Dynamics Study

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• 作者：K. Anitha ; Sadanandam Namsani ; Jayant K Singh
• 刊名：Journal of Physical Chemistry A
• 出版年：2015
• 出版时间：July 30, 2015
• 年：2015
• 卷：119
• 期：30
• 页码：8349-8358
• 全文大小：644K
• ISSN：1520-5215

文摘

The adsorption behaviors of heavy metal ions Cd²⁺, Cu²⁺, Pb²⁺, and Hg²⁺, in aqueous media using functionalized single-walled carbon nanotube (SWCNT) with functional groups 鈭扖OO^{鈥?/sup>, 鈭扥H, and 鈭扖ONH₂ are studied using molecular dynamics (MD) simulations. The results show that adsorption capacity is improved significantly using surface modification of SWCNT with carboxyl, hydroxyl, and amide functional groups. In addition, the adsorption capacity is found to increase with increasing metal-ion concentration. It is observed that the CNT鈥揅OO鈥?/sup> surface effectively adsorbs over 150鈥?30% more metal ions than the bare CNT surface. On the contrary, 鈭扥H and 鈭扖ONH₂ are relatively weak functional groups where excess metal-ion adsorption compared to the bare CNT is in the range 10鈥?7%. The structural properties, self-diffusion coefficients, and adsorption isotherms of the metal ions are computed and analyzed in detail. Moreover, the potential of mean force (PMF) is computed to understand the free energy of metal ions, in the presence of functional groups, which is remarkly higher in absolute terms, leading to significant affinity for adsorption compared to the case for the bare CNT. In general, the following order of adsorption of the metal ions on functionalized CNT is observed: Pb2+ > Cu2+ > Cd2+ > Hg2+.}