Influence Of Fe2O3 And MgO As Mineralizers For Tobermorite Synthesis
Tobermorite (Ca5Si6O16(OH)2.4H2O) crystallites with various morphologies have been successfully synthesized via a hydrothermal process at 175°C for 4 and 24 hours and assisted by Fe2O3 and MgO as mineralizers. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FTIR) indicated that the mineralizers played a key role in the crystallization and morphology-controlled synthesis of tobermorite crystallites. Mg2+ increase crystallinity of tobermorite and change its morphology from platy-shape at 4 hours curing time to lamellar-shape at longer curing time. Fe3+ increases imperfection of tobermerite at short curing time, however it increases crystallinity at longer curing time and the morphology of tobermorite change magnificently from reticulated-shape to fiber-shape. FTIR proved that MgO and Fe2O3 increase silicate chains polymerization and increase the chain cross-linkage, which is consistent with tobermorite lamellar and fibers morphology that grow parallel to the b-axis (along the silicate chains). MgO and Fe2O3 can be used as valuable additives in tobermorite synthesis to tailor the crystal morphology for specific applications like heat insulations with high mechanical properties or used as filters for removal of heavy metal or organic materials from different industrial processes. iÂÂ 2006 Trade Science Inc. - INDIA