Study of the thermal decomposition of a sepiolite by mid- and near-infrared spectroscopies

Near-infrared (NIR) and mid-infrared (MIR) spectroscopies were used to characterize the hydroxyl groups present in a sepiolite and its calcination products at 250, 500 and 800 degrees C. Calcining the sepiolite at 250 degrees C was found to result in its dehydration through the loss of coordination water. Raising the calcination temperature to 500 degrees C caused the sepiolite structure to fold and hydroxyl groups in octahedral layers to be removed. Finally, calcination at 800 degrees C resulted in a phase change leading to enstatite, as confirmed by XRD spectroscopy. (C) 2010 Elsevier Ltd. All rights reserved.