Aragonite–calcite–vaterite: A temperature influenced sequential polymorphic transformation of CaCO{sub 3} in the presence of DTPA
- Department of Chemistry, Annamalai University, Annamalainagar 608002, Tamilnadu (India)
Highlights: ► Crystallization of CaCO{sub 3} between 60 and 230 °C in the presence of DTPA. ► Formation of exclusive and individual polymorphs at different temperatures. ► Violation of second law of thermodynamics/Ostwald rule of stages has been observed. - Abstract: Calcium carbonate was precipitated from calcium chloride using sodium carbonate in the presence of diethylenetriaminepentaacetic acid (DTPA) between 60 and 230 °C. The samples were characterized by FTIR, Raman, XRD and SEM techniques. CaCO{sub 3} with different crystal morphologies such as spherolite/datura pod, dumbbell, peanut, were obtained depending on the experimental conditions. The results showed that pure aragonite, calcite and vaterite were formed at low, moderate and high temperatures respectively. A binary mixture of calcite and vaterite was resulted between 150 and 200 °C. The data suggested an unusual conversion of stable calcite to meta stable vaterite at higher temperature in presence of DTPA. The study revealed a novel methodology for the exclusive/individual preparation of different crystalline polymorphs of CaCO{sub 3}. Formation of pure vaterite above 200 °C divulged the possibility of DTPA as a potential scale inhibitor and boiler sludge conditioner at elevated temperatures.
- OSTI ID:
- 22290435
- Journal Information:
- Materials Research Bulletin, Vol. 48, Issue 5; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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