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Advances in Materials Science and Engineering
Volume 2016, Article ID 2914368, 8 pages
http://dx.doi.org/10.1155/2016/2914368
Research Article

Effects of Calcination on the Crystallography and Nonbiogenic Aragonite Formation of Ark Clam Shell under Ambient Condition

1Department of Physics, Faculty of Science, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia
2School of Chemistry, The University of Sydney, F11, Eastern Avenue, Sydney, NSW 2006, Australia
3Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia
4Department of Chemistry, Faculty of Science, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia

Received 18 November 2015; Accepted 11 January 2016

Academic Editor: Michele Iafisco

Copyright © 2016 Chee Wah Loy 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

This paper presents a study of crystallographic evolution of disposed ark clam shell (ACS) after calcination at 400–1400°C which was kept at room temperature under ambient condition in Malaysia during nine months. A better understanding of hydration and recarbonation of ACS powder (≤63 μm) after calcination was discovered by PXRD and FTIR. The research focuses on the crystallographic transformation, biogenic calcite decomposition, and unusual atmospheric aragonite formation in ACS after calcination and atmospheric air exposure. Ex situ PXRD showed calcite present in ACS at ≤900°C. ACS transformed to pyrogenic fcc CaO at ≥800°C after three months. Long term atmospheric air exposure of decarbonized ACS caused nucleation of nonbiogenic aragonite, vaterite, calcite, and portlandite. However, in situ PXRD analysis of ACS at instantaneous temperature without cooling process does not indicate the presence of aragonite, vaterite, and portlandite crystals. FTIR spectra revealed CaO–CO2 bond in ACS dissociated with temperature (600–900°C) to form CaO and CO2. Ca–OH bond was also traced in FTIR spectra of ≥700°C. It resulted by hydroadsorption of CaO with H2O in atmospheric air.