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Journal of Nanomaterials
Volume 2014, Article ID 749562, 8 pages
http://dx.doi.org/10.1155/2014/749562
Research Article

Preparation and Characterization of Nanosized Hematite Colloids Using Green Vitriol as Ferrum Source

State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510641, China

Received 2 March 2014; Revised 23 March 2014; Accepted 23 March 2014; Published 30 April 2014

Academic Editor: Zhenhui Kang

Copyright © 2014 Xiao-Quan Chen 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 paper reports a green synthetic route for nanosized hematite colloids with an excellent monodispersity, using green vitriol and ammonia as raw materials. The reaction conditions of the synthetic route were studied and the as-prepared samples were characterized by XRD, TEM, TG-DTA, DLS, and XPS. The results indicated that the key factors for the monodispersity of the colloidal product were preheating reactants and washing repeatedly the intermediate Fe(OH)3. When the initial pH was set as 4 or 5, the transformation product of Fe(OH)3 was the pure α-Fe2O3 with the minim adsorptive sulfate ions. Contrarily, the mixtures of α-Fe2O3 and α-FeOOH were obtained at the pH 6 or 7, which were related to the mechanism of transformation reaction. In addition, the concentration of Fe(OH)3 should be less than or equal to 0.2 mol/L in order to prepare the qualified nanosized hematite colloids. The researches proved that the excellent monodispersity of the colloidal product resulted from a fine dispersion state of the synthetic system during the whole process and that it was a significant way to obtain the nanosized metallic oxide colloids from the corresponding metal hydroxide due to avoidance of hyperspeed centrifugal separation or dialysis operation.