Montmorillonite interlayer surface chemistry: effect of magnesium ion substitution on cation adsorption

Lavikainen, Lasse P.; Tanskanen, Jukka T.; Schatz, Timothy; Kasa, Seppo; Pakkanen, Tapani A.

doi:10.1007/s00214-015-1654-2

Cited by 21 publications

(6 citation statements)

References 37 publications

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“…The positions of Mg atoms were selected so the distance between them is as long as possible based on the symmetry. This selection agrees well with previous attempts (Lavikainen et al, 2015). These new periodic models (Fig.…”

Section: Structuressupporting

confidence: 92%

Effect of layer charge on the crystalline swelling of Na⁺, K⁺ and Ca²⁺ montmorillonites: DFT and molecular dynamics studies

2016

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The swelling and cation exchange properties of montmorillonite are fundamental in a wide range of applications ranging from nanocomposites to catalytic cracking of hydrocarbons. The swelling results from several factors and, though widely studied, information on the effects of a single factor at a time is lacking. In this study, density functional theory (DFT) calculations were used to obtain atomic-level information on the swelling of montmorillonite. Molecular dynamics (MD) was used to investigate the swelling properties of montmorillonites with different layer charges and interlayer cationic compositions. Molecular dynamics calculations, with CLAYFF force field, consider three layer charges (−1.0, −0.66 and −0.5 e per unit cell) arising from octahedral substitutions and interlayer counterions of Na, K and Ca. The swelling curves obtained showed that smaller layer charge results in greater swelling but the type of the interlayer cation also has an effect. The DFT calculations were also seen to predict larger d values than MD. The formation of 1, 2 and 3 water molecular layers in the interlayer spaces was observed. Finally, the data from MD calculations were used to predict the selfdiffusion coefficients of interlayer water and cations in different montmorillonites and in general the coefficient increased with increasing water content and with decreasing layer charge.

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Section: Structuressupporting

confidence: 92%

Effect of layer charge on the crystalline swelling of Na⁺, K⁺ and Ca²⁺ montmorillonites: DFT and molecular dynamics studies

2016

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“…The former anti-correlation, which is more prominent, suggests a predominant substitution of P 5+ for Si 4+ balanced either by tetrahedral vacancies 5 IV Si 4+ ¼ 4 IV P 5+ + IV [ ] ([ ] corresponds to vacancies) or by octahedral vacancies as the following: 2 IV Si 4+ + 4 VI D 2+ ¼ 2 IV P 5+ + 3 VI M 2+ + VI [ ]/M (D and M corresponds to divalent and monovalent inter-layer cations, respectively); furthermore, the negative correlation of P 2 O 5 with Al 2 O 3 probably indicates that the Al 3+ cations are exposed on the edge face of the crystal. 24 Thereaer, detailed SEM and electron microprobe analyses are required that should be reected on the mineral composition and the element's inter-relation, in order to infer robust constraints on the substitution mechanisms involved not only within montmorillonite but also in the rest of the silicates (e.g. CASH, plagioclase).…”

Section: Resultsmentioning

confidence: 99%

Sorption mechanism(s) of orthophosphate onto Ca(OH)₂pretreated bentonite

et al. 2016

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“…The higher content of iron(III) in the PetBent sheets (double than in the Bent value) may have prevented a higher percentage of substitution of the exchangeable cations, sodium and calcium, by lanthanum(III) because of the stronger electrostatic effect. 54,55 The second hypothesis is based on the influence of the pore size on the modification. The larger size of the Bent pores, 100 Å, compared to the PetBent pores, 60 Å, may have enhanced the diffusion of the lanthanum(III) solution through the inner regions of the more porous material, thereby contributing to the higher efficiency of the ion exchange process.…”

Section: Preparation and Characterizations Of The Clay Mineralsmentioning

confidence: 99%

Phosphate Adsorption by Montmorillonites Modified with Lanthanum/Iron and a Laboratory Test using Water from the Jacarepaguá Lagoon (RJ, Brazil)

Castro

Brandão

Bertolino

et al. 2018

J. Braz. Chem. Soc.

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Montmorillonites modified with lanthanum(III) and iron(III) were prepared from two commercial clays. These materials were characterized by powder X-ray diffraction analysis, X-ray fluorescence, infrared spectroscopy, N 2 adsorption, and scanning electron microscopy. The incorporation of lanthanum(III) and iron(III) varied from 0 to 4.00%. The amount of these cations governed the adsorption capacity of the material since an increase in the percentage of La by 1.7 times improved the adsorption capacity by 3.3 times. The structural properties of the precursor clay minerals, such as pore size, may have influenced the extension of the modification process. Kinetics and equilibrium studies indicated that adsorption occurs mainly within 24 h, and the pseudo-second order and Lagmuir models described the process. The phosphate adsorption capacity ranged from 2.86 to 17.86 mg g-1 for the modified materials and was mainly dependent on the La content. A laboratory test with a natural water sample from the Jacarepaguá Lagoon showed reduction of the soluble reactive phosphorus concentration from 0.41 to 0.04 mg L-1 , for the material with 4.00% La 2 O 3. The materials described in this work were effective for the reduction of the soluble reactive phosphate, contributing to the research of a national product destined to the restoration of eutrophic aquatic environments.

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Montmorillonite interlayer surface chemistry: effect of magnesium ion substitution on cation adsorption

Cited by 21 publications

References 37 publications

Effect of layer charge on the crystalline swelling of Na⁺, K⁺ and Ca²⁺ montmorillonites: DFT and molecular dynamics studies

Effect of layer charge on the crystalline swelling of Na⁺, K⁺ and Ca²⁺ montmorillonites: DFT and molecular dynamics studies

Sorption mechanism(s) of orthophosphate onto Ca(OH)₂pretreated bentonite

Phosphate Adsorption by Montmorillonites Modified with Lanthanum/Iron and a Laboratory Test using Water from the Jacarepaguá Lagoon (RJ, Brazil)

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Montmorillonite interlayer surface chemistry: effect of magnesium ion substitution on cation adsorption

Cited by 21 publications

References 37 publications

Effect of layer charge on the crystalline swelling of Na+, K+ and Ca2+ montmorillonites: DFT and molecular dynamics studies

Effect of layer charge on the crystalline swelling of Na+, K+ and Ca2+ montmorillonites: DFT and molecular dynamics studies

Sorption mechanism(s) of orthophosphate onto Ca(OH)2pretreated bentonite

Phosphate Adsorption by Montmorillonites Modified with Lanthanum/Iron and a Laboratory Test using Water from the Jacarepaguá Lagoon (RJ, Brazil)

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Effect of layer charge on the crystalline swelling of Na⁺, K⁺ and Ca²⁺ montmorillonites: DFT and molecular dynamics studies

Effect of layer charge on the crystalline swelling of Na⁺, K⁺ and Ca²⁺ montmorillonites: DFT and molecular dynamics studies

Sorption mechanism(s) of orthophosphate onto Ca(OH)₂pretreated bentonite