• ITATANI KIYOSHI

      Articles written in Bulletin of Materials Science

    • Lead ions removal from aqueous solution using modified carbon nanotubes

      NGUYEN DUC VU QUYEN TRAN NGOC TUYEN DINH QUANG KHIEU HO VAN MINH HAI DANG XUAN TIN PHAM THI NGOC LAN ITATANI KIYOSHI

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      Surface-modified carbon nanotubes (CNTs) were prepared in order to remove lead ions (Pb$^{2+}$) from aqueoussolution. The modification of CNTs was conducted by oxidation, using a mixture of nitric acid (HNO$_3$) and sulphuric acid(H$_2$SO$_4$). The adsorption behaviour was well fitted to the Langmuir model and the maximum adsorption capacity of Pb$^{2+}$ was found to be 100 mg g$^{−1}$. The adsorption of Pb$^{2+}$ reached equilibrium in 80 min. The experimental data were well fitted to a pseudo-second-order rate model rather than a pseudo-first-order model. The activation energy and activation enthalpy of the adsorption calculated from Arrhenius and Eyring equations were, respectively, 21.08 and 18.56 kJ mol$^{−1}$, which reflect the outside surface adsorption and ion exchange mechanism. The thermodynamical studies showed that the adsorption of Pb$^{2+}$ was a spontaneous and endothermic process. The ion exchange mechanism of Pb$^{2+}$ removal was confirmed by the pH and electrical conductivity data in solution before and after adsorption.

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