Abstract:In this work, a bentonite clay from Mendoza, Argentina was activated with H2SO4 (4 and 8 N) at 90ºC for 2 and 3.5 hours. Under these conditions several cations were removed from the octahedral sheet (Mg, Al, and Fe) and the DTA-TGA curves of the solids obtained after treatment were modified. Treatment time and acid concentration increased the degree of destruction of the bentonite structure. Activated samples were tested in order to verify their capacity to bleach soybean oil and were compared to a standard co… Show more
“…The bentonite sample (40 g) was treated with 400 mL of 4 N or 8 N sulphuric acid (analytical grade) at 90°C for 3.5 h (Foletto et al, 2003) in a stirred glass reaction vessel with reflux. After the acid treatment, the sample was filtered and washed with distilled water until free of SO 4 2-.…”
Section: Methodsmentioning
confidence: 99%
“…The loss of weight due to dehydroxylation (%) of the samples, obtained from TGA curves, occurred in the range 450-750°C (Figure 1); the TGA curves were used for the evaluation of the extent of the attack of the acid treatment on the octahedral sheets ( Table 2). The octahedral sheet destruction was calculated as a relative percentage reduction of the weight loss, with respect to the original sample (Foletto et al, 2003). The activated K samples showed 14 to 19% destruction of the octahedral sheet, while the activated W samples showed 12 to 15% destruction.…”
Section: +mentioning
confidence: 99%
“…They have also been used in the foodstuffs industry, for sulphur production, forest and water conservation, in the chemical industry, for environmental protection, and in the paper industry (Clarke, 1985, O'Driscoll, 1988, as well as for bleaching of vegetable oils (Srasra et al, 1989, Christidis et al, 1997, Foletto et al, 2003, Kirali and Laçin, 2006. The bleaching of edible vegetable oils involves the removal of a variety of impurities, which include phosphatides, fatty acids, gums, trace metals, etc., followed by decolorization.…”
-Two bentonite clays with different mineralogical compositions from Mendoza, Argentine, were activated with H 2 SO 4 solutions of 4 and 8 N at 90°C for 3.5 hours. This treatment affected clay structural properties, as was shown by thermogravimetry, infrared spectrometry and chemical analysis. Bleaching efficiency for sunflower oil was strongly dependent on the acid concentration used for clay activation. The samples have bleaching capacity comparable to that observed with a commercial adsorbent standard. The mineralogical composition of natural clays influenced the properties of the activated clays.
“…The bentonite sample (40 g) was treated with 400 mL of 4 N or 8 N sulphuric acid (analytical grade) at 90°C for 3.5 h (Foletto et al, 2003) in a stirred glass reaction vessel with reflux. After the acid treatment, the sample was filtered and washed with distilled water until free of SO 4 2-.…”
Section: Methodsmentioning
confidence: 99%
“…The loss of weight due to dehydroxylation (%) of the samples, obtained from TGA curves, occurred in the range 450-750°C (Figure 1); the TGA curves were used for the evaluation of the extent of the attack of the acid treatment on the octahedral sheets ( Table 2). The octahedral sheet destruction was calculated as a relative percentage reduction of the weight loss, with respect to the original sample (Foletto et al, 2003). The activated K samples showed 14 to 19% destruction of the octahedral sheet, while the activated W samples showed 12 to 15% destruction.…”
Section: +mentioning
confidence: 99%
“…They have also been used in the foodstuffs industry, for sulphur production, forest and water conservation, in the chemical industry, for environmental protection, and in the paper industry (Clarke, 1985, O'Driscoll, 1988, as well as for bleaching of vegetable oils (Srasra et al, 1989, Christidis et al, 1997, Foletto et al, 2003, Kirali and Laçin, 2006. The bleaching of edible vegetable oils involves the removal of a variety of impurities, which include phosphatides, fatty acids, gums, trace metals, etc., followed by decolorization.…”
-Two bentonite clays with different mineralogical compositions from Mendoza, Argentine, were activated with H 2 SO 4 solutions of 4 and 8 N at 90°C for 3.5 hours. This treatment affected clay structural properties, as was shown by thermogravimetry, infrared spectrometry and chemical analysis. Bleaching efficiency for sunflower oil was strongly dependent on the acid concentration used for clay activation. The samples have bleaching capacity comparable to that observed with a commercial adsorbent standard. The mineralogical composition of natural clays influenced the properties of the activated clays.
“…• can be ascribed to the characteristic diffraction of quartz and chrystoballite impurities [34], respectively, which indicated the existence of quartz impurities. Moreover, the diffraction peaks at 2θ = 21.6…”
Section: X-ray Diffraction Analysis Of the Samplesmentioning
Abstract:Clay from Kono-bowe, Nigeria, was activated thermally and chemically and used to remove lead(II) and chromium(III) ions from aqueous solution. The effects of adsorption process variables were studied as well as the kinetics and equilibrium of the process. Analysis of the activated samples showed that the surface area, cation exchange capacity, and adsorption performance were positively favored by both activation processes. It was observed that the adsorption rate increased with an increase in temperature, contact time, adsorbent dosage, initial ion concentration, and solution pH values. The pH P ZC of the adsorbents was determined to be 6.5, 7.4, and 7.2, for KBR, KBTA, and KBAA, respectively.It was observed that sample KBAA yielded maximum adsorption efficiency of 99.9% for the removal of chromium(III), and gave maximum adsorption efficiency of 98.7% for lead(II) removal. The results of the kinetics analysis of the adsorption data revealed that adsorption follows pseudo-second-order kinetics. Analysis of the equilibrium data showed that the Langmuir isotherm provided a better fit to the experimental data for KBR, while the Freundlich isotherm fitted the experimental data of KBTA and KBAA. Evaluation of the thermodynamic parameters revealed that the adsorption process is spontaneous and endothermic.
“…Therefore, natural clays can be used as promising low-cost adsorbents, once they are abundant and inexpensive. Bentonite is clay predominantly composed of a smectite mineral, which is widely used in a variety of industrial applications (Murray, 1999;Foletto et al, 2003Foletto et al, , 2011. Herein, locally available bentonite clay from Brazil southern was used as low-cost adsorbent for the removal of RhB dye from aqueous solutions.…”
Abstract:The potential of a Brazilian natural bentonite to remove Rhodamine B (RhB) dye from aqueous solutions was evaluated. The bentonite was characterised by X-ray diffraction, thermogravimetric analysis, particle size distribution and N 2 -adsorption isotherms. The adsorption of RhB onto bentonite was evaluated in batch system. The pH effect (2.5-10.5), kinetic curves and equilibrium isotherms (initial dye concentrations from 100 to 600 mg L -1 ) were studied at 25°C and 250 rpm. It was found that the Brazilian bentonite presented a mesoporous structure with surface area of 14.35 m 2 g -1and average pore size of 28 nm. The adsorption capacity remained practically 2
B.M. Zimmermann et al.constant from pH 2.5 to pH 10.5. The Elovich model was adequate to represent the adsorption kinetic curves. Langmuir and Freundlich models were suitable to represent the adsorption isotherm. The maximum adsorption capacity was 77.3 mg g -1 , obtained at 25°C, pH of 4.5 and adsorbent dosage of 500 mg L -1 . It was demonstrated that the Brazilian bentonite can be utilised as a promising adsorbent to remove RhB from aqueous solutions.
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