Surface properties of an activated bentonite — Decolorisation of rape-seed oils

Characterization of Unye bentonite after treatment with sulfuric acid

“…18,22 The intensity of the d 001 peak of montmorillonite at 15.33 Å in RB drastically decreased in the diffraction patterns of 0.2-AAB and 0.4-AAB (Figure 1b-c). Meanwhile, the d 060 peak at 1.50 Å, which is typical of dioctahedral smectites, 14,23 reached a maximum in the 0.4-AAB pattern. The intensity of the d 004 and d 005 peaks of montmorillonite, which were seen as combined features with those of tridymite (T) at 3.80 and 2.99 Å, 24,25 paralleled the weakening of the d 001 peak.…”

“…21,31 The increase in the surface area results from the initial replacement of exchangeable cations by protons, which is followed by the extraction of Al, Fe, and Mg atoms from octahedral and tetrahedral sites. 13,14,32 Both the mesoporous volume (0.4023 cm 3 /g) and the mesoporous area (299.7±0.4 m 2 /g) reached a maximum for 0.4-AAB, because the vacancies that occurred The reduction of the specific surface area to 182.7±0.8 m 2 /g for 0.6-AAB may be ascribed to the change in the porosity distribution. Implicit in the above trend is the fact that the partial destruction of the smectite structure gave rise to the growth of an alumino-silicate phase as the result of the cross-linking of the residual tetrahedral sheets.…”

“…[11][12][13] Thus it is necessary to take into account the mineralogical composition of clay deposits in order to apply acid leaching at an appropriate acid/clay ratio for the preparation of clay products that retain a layered morphology. [14][15][16] The most important parameter that determines the catalytic power and adsorption capacity of clay-based materials is the amount of accessible surface area. Altering the total number of micropores and mesopores via acid activation leads to significant changes in the surface area, porosity, and reactivity of the end product and directly influences the adsorptive properties of clays.…”

Acid Hydrolysis of Octahedral Mg2+ Sites in 2:1 Layered Silicates: An Assessment of Edge Attack and Gallery Access Mechanisms

“…Octahedral cations such as A13+, Fe 3+, Fe z+, and Mg 2+ can be depleted by treating the clay minerals with acids at elevated temperatures (Johnson et al 1964; with the rates of depletion generally following the order Mg 2+ > Fe 2 § Fe 3+ > AP + Luce et al 1972;Rice and Strong 1974). There has been considerable interest in the acid hydrolysis of 2:1 clay structures, especially palygorskite (Corma et al , 1990Gonzalez et al 1989), sepiolite (Corma et al 1986;Rodriguez-Reinoso et al 1981), montmorillonite (Mendioroz et al 1987;Rhodes and Brown 1992;Srasra et al 1989), and vermiculite (Suquet et al 1991). BET surface areas as high as 500 m2/g have been reported for the amorphous silicates derived from some of these minerals.…”

Response surface modeling of acid activation of raw diatomite using in sunflower oil bleaching by: Box–Behnken experimental design

“…Bleaching power is dependent on the surface area, surface acidity, catalytic activity, porosity and pore size distribution of the bleaching earth (Breen et al 1997;Önal et al 2002;Srasra et al 1989;Vicente-Rodriquez et al 1996). These physicochemical properties of bleaching earths change depending on the mineralogical and chemical composition of the activated bleaching earth, type and concentration of the inorganic acid, used in the process and also temperature and time of activation.…”