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Advances in Materials Science and Engineering
Volume 2014 (2014), Article ID 706041, 12 pages
http://dx.doi.org/10.1155/2014/706041
Research Article

Thermal Treatment of Cerium Oxide and Its Properties: Adsorption Ability versus Degradation Efficiency

1Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem, Czech Republic
2Faculty of Science, University of Jan Evangelista Purkyně, České Mládeže 8, 400 96 Ústí nad Labem, Czech Republic

Received 21 January 2014; Revised 28 March 2014; Accepted 11 April 2014; Published 11 June 2014

Academic Editor: Zhimin Liu

Copyright © 2014 Pavel Janoš 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

Cerium oxide belongs to the most important heterogeneous catalysts, but its applicability as so-called reactive sorbent for the degradation of toxic chemicals was only recently discovered. For these purposes, cerium oxide is prepared by precipitation of insoluble cerium salts (carbonates) with a subsequent thermal decomposition. Properties of cerium oxide prepared from the carbonate precursor are strongly affected by the temperature during the calcination. Main physicochemical properties of cerium oxide (specific surface area, crystallinity, and surface chemistry) were examined in dependence on the calcination temperature. As the adsorptive properties of CeO2 are undoubtedly of great importance in the abovementioned applications, the adsorption ability was studied using an azo dye Acid Orange 7 (AO7) as a model compound. The highest sorption efficiency towards AO7 exhibited sorbents prepared at temperatures below 700°C, which was attributed mainly to the presence of hydroxyl groups on the oxide surface. A strong correlation was found between an adsorption efficiency of cerium oxides and their degradation efficiency for organophosphate pesticide parathion methyl. The >Ce–OH groups on the sorbent surface are responsible for the dye binding by the surface-complexation mechanism, and probably also for the nucleophilic cleavage of the P–O–aryl bond in the pesticide molecule.