Alteration of swelling clay minerals by acid activation

Steudel, Annett; Batenburg, Lawrence F.; Fischer, Hartmut; Weidler, Peter G.; Emmerich, Katja

doi:10.1016/j.clay.2009.02.002

Cited by 164 publications

(80 citation statements)

References 25 publications

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“…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. 17,20 Thereafter, a similar trend continued with further activation in line with the acid/clay ratio, and the influence of the free silica became more important, yielding even a smaller specific surface area (168.8±0.9 m 2 /g) in 0.8-AAB. The decrease in the specific surface area also reflected the fact that the acid treatment dissolved the impurities and reduced the effect of the enlarged radii of the mesopores in which the protons could easily open the edges of the platelets and expand the pore diameter.…”

Section: Surface Area Measurements Of Raw and Acid-activated Bentonitesmentioning

confidence: 77%

“…The initial exchange of H + for Na and Ca in the interlayer of the bentonite and other minerals and the relative resistance of the feldspar, cristabolite, and tridymite impurities to acid treatment (Table 1) are consistent with previously reported results for non-swelling phyllosilicate layers. [18][19][20] XRPD patterns of raw and acid-activated bentonites Figure 1 shows the XRPD patterns of the RB and AAB samples. (Figure 1a).…”

Section: Chemical Composition Of Raw and Acid-activated Bentonitesmentioning

confidence: 99%

“…[17][18][19] Furthermore, the composition of the smectite layers substantially affects their stability against acid treatment; trioctahedral clays dissolve much faster than their dioctahedral counterparts, and the extent of dissolution of the central atoms from the tetrahedral and octahedral sheets depends on both the clay mineral type and the reaction conditions, such as the acid concentration, time, and temperature of the treatment. 20,21 The uses of the bentonite deposits in Turkey vary depending on the types and amounts of constituents found, such as smectites, other clay minerals, and non-clay minerals, including quartz, calcite, dolomite, and feldspar. Therefore, there seems to be the need for the careful investigation of the structural properties of these bentonites under different conditions in order to be able to use them more efficiently.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Unye bentonite after treatment with sulfuric acid

Çağlar¹,

Afsin²,

Koksal³

et al. 2013

Quím. Nova

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Recebido em 4/9/12; aceito em 25/3/13; publicado na web em 13/6/13Unye bentonite was found to consist predominantly of a dioctahedral smectite along with quartz, tridymite, cristobalite, and minor fractions of feldspar and anatase. A considerable amount of Al was retained as a constituent in acid-resistant impurities following the decomposition of the montmorillonite via acid treatment at an acid/clay ratio of 0.4. These impurities were mesoporous with a maximum surface area of 303.9±0.4 m 2 g -1 . A sharp decrease in the d 001 lattice spacing of the montmorillonite to 15.33 Å reflected the reduction of the crystallinity in the activated products. In addition, the increase in the ease with which newly formed hydroxyl groups were lost paralleled the severity of the acid treatment.

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Section: Surface Area Measurements Of Raw and Acid-activated Bentonitesmentioning

confidence: 77%

Section: Chemical Composition Of Raw and Acid-activated Bentonitesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Unye bentonite after treatment with sulfuric acid

Çağlar¹,

Afsin²,

Koksal³

et al. 2013

Quím. Nova

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“…The spectrum of the untreated bentonite exhibits absorption bands at 3422 and 1638 cm −1 this is assigned to the stretching and bending vibrations of the OH groups for the water molecules adsorbed on the clay surface, and a band at 3621 cm −1 which represents the stretching vibration of the hydroxyl groups coordinated to octahedral Al 3+ cations [27] [31]. The spectra show sharp band vibrations in the region between 1000 and 400 cm −1 it is described in earlier papers [32] [33]. Namely, the most intensive band at 1035 cm −1 in the spectra of untreated bentonite was attributed to Si-O stretching vibrations (in-plane) of the tetrahedral sheets, whereas the bands around 521 and 466 cm −1 are ascribed to Si-O-Al (where Al is the octahedral cation) and Si-O-Si bending vibrations, respectively [34].…”

Section: Ftir Characterizationmentioning

confidence: 81%

Effect of Hydrochloric Acid on the Structural of Sodic-Bentonite Clay

Bendou¹,

Amrani²

2014

JMMCE

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The objective of this work is to determine changes of surface properties of a bentonite after acid activation, using hydrochloric acid solutions (HCl) at room temperature. XRD, FX, FTIR, MEB, and BET analyses of the samples have been carried out to examine the structure of bentonite before and after acid activation. It is found that the raw bentonite is composed of dioctahedral montmorillonite with predominant quantity and certain amounts of quartz, albite and illite, etc. It has an cation exchange capacity (CEC) of 74.32 meq/g which allows it to be characterized as typical sodium bentonite. The changes, at low acid concentrations, are the result from from cation exchange (exchangeable cations with H + ions). Differences of surface area at high acid concentrations (0.25 -0.4 M) were caused by structural changes and partial decomposition of the samples. Data of surface area measurements have showed that with increase of concentration of hydrochloric acid, the surface area increased. The maximum value (837.11 m 2 /g) was reached by the sample activated with 0.4 M HCl. By against, activation with higher concentration (0.6 M) caused a decrease in the surface area.

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“…Table 1 displays the approximate chemical composition of montmorillonites from each sample. Purification and separation of montmorillonite from bentonite is described in Steudel et al (2009). For layer charge measurement of the raw material, separation of the montmorillonite from the accompanying bentonite was not necessary.…”

Section: Methodsmentioning

confidence: 99%

Correlation Between the Extent of Catalytic Activity and Charge Density of Montmorillonites

et al. 2010

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The clay mineral montmorillonite is a member of the phyllosilicate group of minerals, which has been detected on martian soil. Montmorillonite catalyzes the condensation of activated monomers to form RNA-like oligomers. Extent of catalysis, that is, the yield of oligomers, and the length of the longest oligomer formed in these reactions widely varies with the source of montmorillonite (i.e., the locality where the mineral is mined). This study was undertaken to establish whether there exists a correlation between the extent of catalytic property and the charge density of montmorillonites. Charge density was determined by saturating the montmorillonites with alkyl ammonium cations that contained increasing lengths of alkyl chains, [CH 3 þ , where n ¼ 3-16 and 18, and then measuring d (001) , interlayer spacing of the resulting montmorillonite-alkyl ammoniummontmorillonite complex by X-ray diffractometry (XRD).Results demonstrate that catalytic activity of montmorillonites with lower charge density is superior to that of higher charge density montmorillonite. They produce longer oligomers that contain 9 to 10 monomer units, while montmorillonite with high charge density catalyzes the formation of oligomers that contain only 4 monomer units.The charge density of montmorillonites can also be calculated from the chemical composition if elemental analysis data of the pure mineral are available. In the next mission to Mars, CheMin (Chemistry and Mineralogy), a combined X-ray diffraction/X-ray fluorescence instrument, will provide information on the mineralogical and elemental analysis of the samples. Possible significance of these results for planning the future missions to Mars for the search of organic compounds and extinct or extant life is discussed.

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Alteration of swelling clay minerals by acid activation

Cited by 164 publications

References 25 publications

Characterization of Unye bentonite after treatment with sulfuric acid

Characterization of Unye bentonite after treatment with sulfuric acid

Effect of Hydrochloric Acid on the Structural of Sodic-Bentonite Clay

Correlation Between the Extent of Catalytic Activity and Charge Density of Montmorillonites

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