Sorption/desorption of radionickel on/from Na-montmorillonite: kinetic and thermodynamic studies |
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Authors: | Email author" target="_blank">Tao?HuEmail author Liqiang?Tan |
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Institution: | (1) Faculty of Life Science and Chemical Engineering, Huaiyin Institute of Technology, Huaian, 223003, People’s Republic of China;(2) National Special Superfine Powder Engineering Center, Nanjing University of Science and Technology, Nanjing, 210094, People’s Republic of China |
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Abstract: | In this work, Na-montmorillonite was used as a novel adsorbent for the sorption of Ni(II) from aqueous solutions. The sorption
and desorption of Ni(II) on Na-montmorillonite was investigated as the function of pH, ionic strength, Ni(II) concentrations
and temperature. The results indicated that the sorption of Ni(II) on Na-montmorillonite was strongly dependent on pH, ionic
strength and temperature. The sorption of Ni(II) increases slowly from 22.1 to 51.4% at pH range 2–6.5, abruptly at pH 6.5–9,
and at last maintains high level with increasing pH at pH > 9 in 0.1 mol/L NaNO3 solutions. The Ni(II) kinetic sorption on Na-montmorillonite was fitted by the pseudo-second-order model better than by the
pseudo-first-order model and the experimental data implies that Ni(II) sorption on montmorillonite were mainly controlled
by the film diffusion mechanism. The Langmuir, Freundlich and D–R models were used to simulate the sorption data at three
different temperatures (298.15, 318.15 and 338.15 K) and the results indicated that Langmuir model simulates the experimental
data better than Freundlich and D–R models. The sorption–desorption isotherm of Ni(II) on montmorillonite suggested that the
sorption is irreversible. The irreversible sorption of Ni(II) on montmorillonite indicates that montmorillonite can be used
to pre-concentration and solidification of Ni(II) from large volumes of solution and to storage Ni(II) ions stably. |
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