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Journal of Nanomaterials
Volume 2008, Article ID 168716, 9 pages
http://dx.doi.org/10.1155/2008/168716
Research Article

The Effect of Stirring on the Morphology of Birnessite Nanoparticles

1Department of Health Physics, University of Nevada, Las Vegas, NV 89154, USA
2Department of Chemistry, University of Nevada, Las Vegas, NV 89154, USA
3Grupo de Bio-Geoquimica Ambiental, LAFQA, Instituto de Geografia, Ciudad Universitaria, UNAM, Coyoacan 04510, Mexico
4Department of Aerospace Engineering, Old Dominion University, Norfolk, VA 23529-0247, USA
5School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, South Korea

Received 13 February 2008; Accepted 6 May 2008

Academic Editor: Sang-Hee Cho

Copyright © 2008 Marcos A. Cheney 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

The effect of mechanical stirring on the morphology of hexagonal layer-structure birnessite nanoparticles produced from decomposition of KMnO4 in dilute aqueous H2SO4 is investigated, with characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N2 adsorption (BET). Mechanical stirring during an initial stage of synthesis is shown to produce black birnessite containing nanofibers, whereas granular particulates of brown birnessite are produced without stirring. This is the first reduction synthesis of black birnessite nanoparticles with dendritic morphology without any use of organic reductant, and suggests that a particular morphology can arise from structural preferences of Mn in acidic conditions rather than particular organic reactants. These results enlighten the possibility of synthesizing nanoparticles with controlled size and morphology.