Akademik Veri Yönetim Sistemi
CLAYS AND CLAY MINERALS, cilt.56, sa.5, ss.511-519, 2008 (SCI-Expanded)
Various physicochemical characteristics of a sepiolite sample from the Eskisehir area, Turkey, were investigated to help in making prediction about possible uses of the material. The sample was examined by chemical analysis (CA), thermal analysis (DTA/TGA), X-ray diffraction (XRD) analysis. particle-size analysis (PSA), linear dilatometry (LD). scanning electron microscopy(SEM), mercury porosimetry (Hg-Por.), and low-temperature nitrogen adsorption/desorption (N-2-AD) techniques. The CA and XRD data indicated that the sepiolite contains only 6% dolomite by mass. The XRD patterns showed that sepiolite anhydride, enstatite, diopside, and opal-CT form upon heating the sepiolite above 600, 800, 900. and 1200 degrees C, respectively. The maximum rate of endothermic changes in the DTA and TGA curves were observed at 82, 287, and 491 degrees C, corresponding to the loss of external, zeolitic, and bound water from the sepiolite, respectively. Dehydroxylation and recrystallization of the sepiolite were fastest at 845 degrees C and 862 degrees C, respectively. The LD curve indicated that the shrinkage began at 800 degrees C and reached 4.0% at 1000 degrees C. The proportion of particles with diameters of < 2 mu m, and the external surface area of the long-term (24 h) water-treated sepiolite were determined by PSA as 79% by volume, and 8 m(2) g(-1), respectively. The SEM view revealed discrete bundles of sepiolite fibers of a various lengths. The specific surface area found from adsorption data was 316 m(2) g(-1). The specific micro-, meso-, macro-, and total-pore volumes obtained from the combination of Hg-Por. and N-2-AD results were 0.16. 0.21, 0.45, and 0.82 cm(3) g(-1), respectively. The average macropore and micro-mesopore radii in the sepiolite were estimated (using the Hg-Por. and N-2-AD data) to be 35 and 2.4 nm, respectively.