Influence of Ce3+ on the Formation of α-Semi-Hydrate Gypsum

• Main Authors: Nora KYBARTIENĖ, Violeta LEŠKEVIČIENĖ, Zenonas VALANČIUS
• Format: Article
• Language: English
• Published: Kaunas University of Technology 2012-12-01
• Series: Medžiagotyra
• Subjects: gypsum; α-semi-hydrate gypsum; cerium sulphate octahydrate; dehydration; crystal morphology
• Online Access: http://matsc.ktu.lt/index.php/MatSc/article/view/3102

<p>Influence of Ce³⁺on the formation of α-semi-hydrate gypsum was investigated in this work. α-semi-hydrate gypsum is normally obtained by heat conversion of the dihydrate gypsum. The model system: CaSO₄·2H₂O–Ce₂(SO₄)₃×8H₂O was designed. The amount of Ce₂(SO₄)₃×8H₂O corresponding to 0.1; 0.5 and 1 % of Ce₂O₃ from the mass of dry materials (gypsum) was added to solution. Maleic anhydride (C₄H₂O₃)was used as crystal modifier and 0.1 % of C₄H₂O₃ from the mass of dry materials (gypsum) was added to solution. Water/gypsum of the suspension was equal to 2. The system was processed under hydrothermal conditions at 128°C ±2°C and 138°C ±2°C temperature; the duration of isothermal curing was 3 hours. The product obtained was treated at 400°C temperature. The X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) scanning electron microscopy (SEM) was used to characterize the product.</p> The results showed that the larger amount of Ce³⁺in the system, the larger the remaining amount of un-dehydrated dihydrate gypsum in the final product, and the resulting crystals of α-semi-hydrate gypsum are tiny, indefinite and irregular in shape. Therefore, the results obtained lead to a conclusion that Ce³⁺has a negative influence on the dehydration of dihydrate gypsum (or on the formation of α-semi-hydrate gypsum) and the morphology of α-semi-hydrate gypsum crystals.<p>DOI: <a href="http://dx.doi.org/10.5755/j01.ms.18.4.3102">http://dx.doi.org/10.5755/j01.ms.18.4.3102</a></p>