caa a22 4500 463189582 CHVBK 20180406164904.0 cr unu---uuuuu 170326e20071001xx s 000 0 eng 10.1007/s10973-005-7799-9 doi (NATIONALLICENCE)springer-10.1007/s10973-005-7799-9 Thermal behavior of a bentonite [Elektronische Daten] [M. Önal, Y. Sarıkaya] The mineralogical composition of the Kütahya calcium bentonite (CaB) from Turkey was obtained as mass% of 60% calcium rich smectite (CaS), 30% opal-CT (OCT), trace amount illite (I), and some non-clay impurities by using chemical analysis (CA), X-ray diffraction (XRD), and thermal analysis (TG-DTA) data. The crystallinity, porosity, and surface area of the samples heated between 25-1300°C for 2 h were examined by using XRD, TG, DTA and N2-adsorption-desorption data. The position of the 001 reflection which is the most characteristic for CaS does not affect from heating between 25-600°C and then disappeared. The decrease in relative intensity (I/I 0) from 1.0 to zero and the increase in full width at half-maximum peak height (FWHM) from 0.25 to 1.0° of the 001 reflection show that the crystallinity of the CaS decreased continuously by rising the heating temperature from 25 to 900°C and then collapsed. The most characteristic 101 reflection for opals intensifies greatly between 900 and 1100°C with the opal becoming more crystalline. The total water content of the natural bentonite after dried at 25, 105 and 150°C for 48 h were determined as 8.8, 5.0 and 2.5%, respectively. The mass loss occurs between 25 and 400°C over two steps with the maximum rate at 80 and 150°C, respectively. The exact distinction of the dehydration temperatures for the adsorbed water and interlayer water is seen almost impossible. The temperature interval, maximum rate temperature, and mass loss during dehydroxylation are 400-800°C, 670°C and 4.6-5.0%, respectively. The maximum rate temperatures for decrystallization and recrystallization are 980 and 1030°C, respectively. The changes in specific micropore volume (V mi), specific mesopore volume (V me), specific surface area (S) were discussed according to the dehydration and dehydroxylation of the CaS. The V mi, V me and S reach to their maxima at around 400°C with the values of 0.045, 0.115 cm3 g−1 and 90 m2 g−1, respectively. The radii of mesopores for the bentonite heated at 400°C are distributed between 1-10 nm and intensified approximately at 1.5 nm. Springer Science+Business Media, LLC., 2007 bentonite nationallicence crystallinity nationallicence porosity nationallicence smectite nationallicence thermal analysis nationallicence X-ray diffraction nationallicence Önal M. Faculty of Science, Department of Chemistry, Ankara University, Tando ğan, 06100, Ankara, Turkey aut Sarıkaya Y. Faculty of Science, Department of Chemistry, Ankara University, Tando ğan, 06100, Ankara, Turkey aut Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/1(2007-10-01), 167-172 1388-6150 90:1<167 2007 90 10973 https://doi.org/10.1007/s10973-005-7799-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-005-7799-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Önal M. Faculty of Science, Department of Chemistry, Ankara University, Tando ğan, 06100, Ankara, Turkey aut NATIONALLICENCE 700 1- Sarıkaya Y. Faculty of Science, Department of Chemistry, Ankara University, Tando ğan, 06100, Ankara, Turkey aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/1(2007-10-01), 167-172 1388-6150 90:1<167 2007 90 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer