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Journal of Chemistry
Volume 2016, Article ID 8285717, 9 pages
http://dx.doi.org/10.1155/2016/8285717
Research Article

Synthesis of α-MnO2 Nanomaterial from a Precursor γ-MnO2: Characterization and Comparative Adsorption of Pb(II) and Fe(III)

1Dong Nai University, Tan Hiep Ward, Biên Hòa City, Đồng Nai Province, Vietnam
2Dalat University, Dalat City, Lâm Đồng Province, Vietnam
3Vietnam Atomic Energy Institute, Hanoi, Vietnam

Received 27 July 2016; Accepted 8 September 2016

Academic Editor: Frederic Dumur

Copyright © 2016 Van-Phuc Dinh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

α-MnO2 nanostructure was successfully synthesized via hydrothermal treatment of a precursor γ-MnO2. Structure, morphology, and BET surface area were characterized using X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), and Brunauer-Emmett-Teller nitrogen adsorption (BET-N2 adsorption). Thermal analysis result showed that α-MnO2 nanorods were formed from γ-MnO2 at 600°C. In addition, Pb(II) and Fe(III) adsorptive properties were investigated in an optimal condition. Results showed that equilibrium adsorption was obtained after 60 minutes for Pb(II) at pH = 4.0 and 80 minutes for Fe(III) at pH = 3.5 with 240 rpm of shaking speed overall. Experimental data was analyzed using three models: Langmuir, Freundlich, and Sips. Adsorption capacities () from the Langmuir isotherm models are 124.87 mg/g for Pb(II) and 30.83 mg/g for Fe(III). Along with the highest corelation coefficients, it is clear that the adsorption of Pb(II) and Fe(III) ions on α-MnO2 surface followed Sips model. Kinetic studies indicated that the uptake of Pb(II) and Fe(III) occurred in the pseudo-second-order model with two stages for Pb(II) and three stages for Fe(III).