Silylation of a crystalline silicic acid: an MAS NMR and porosity study

Thiesen, Peter; Beneke, K.; Lagaly, G.

doi:10.1039/b204314a

Cited by 46 publications

(6 citation statements)

References 53 publications

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“…The same success of grafting silane on the surface of kenyaite clay was achieved after performing gelification in the presence of octylamine and reaction at room temperature [61]. Kenyaite was also recently reacted with APTES and dodecylamine in ethanol, resulting in interlayer surface silylation.…”

Section: Clay Modification Via Silane-coupling Reactionmentioning

confidence: 81%

Modified clay for the synthesis of clay-based nanocomposites

Penaloza¹

2019

Epitoanyag - JSBCM

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This review article highlights usual surface modification methodologies in clay fillers for polymer nanocomposites. In clay-based polymer nanocomposites preparation, a key step is the homogeneous dispersion and random orientation of the silicate platelets, like that of montmorillonite (MMT), in the polymer matrix resulting in an exfoliated nanohybrid materials, where significant works in the literature support enhanced and/or new properties of the resulting nanocomposites compared to the bare polymer. In incorporating the MMT clay as a filler in a polymeric material, the surface modification of an MMT clay is necessary. An MMT clay is made up of layered silicates carrying negative charges held together by metal cations found in the galleries between the clay layers. If left unmodified, the native clay exists as aggregates. To improve its miscibility toward organic molecules, it is necessary to modify the clay fillers for polymer nanocomposites.

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Section: Clay Modification Via Silane-coupling Reactionmentioning

confidence: 81%

Modified clay for the synthesis of clay-based nanocomposites

Penaloza¹

2019

Epitoanyag - JSBCM

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“…During the silylation, the acid enhances the extraction of the (organic) cation residing in the interlayer region, supports the hydrolysis of the silylating agent ( Because of the protonation of the ≡Si-O¯groups, the layered precursor may-at least locally and in a state of transition-be considered a CSA. Already, in 2002, Thiesen et al used a very similar silylating agent, dimethyldimethoxysilane (DMDMS), among other alkylmethoxysilanes on a kenyaite-like hydrous potassium silicate [40]. In this case, the authors chose a two-step procedure: the corresponding silicic acid was prepared and subsequently modified with dimethyldimethoxysilane.…”

Section: H-carletonite H32si64o144mentioning

confidence: 99%

Synthesis and Crystal Structures of Two Crystalline Silicic Acids: Hydrated H-Apophyllite, H16Si16O40 • 8–10 H2O and H-Carletonite, H32Si64O144

Marler,

Grosskreuz

2024

Crystals

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Hydrated H-Apophyllite (HH-Apo) and H-carletonite (H-Car) were synthesized at 0 °C by leaching an apophyllite and a carletonite single crystal in a large surplus of 1.2 molar hydrochloric acid. The XRD powder patterns of HH-Apo and H-Car were indexed with space group symmetries of P4/ncc and I4/mcm and lattice parameters of a = 8.4872(2) Å, c = 16.8684(8) Å and a = 13.8972(3) Å, c = 20.4677(21) Å, respectively. The crystal structures were solved based on model building of the structures of the precursors and a physico-chemical characterization. Rietveld structure refinements confirmed the structure models. HH-Apo and H-Car are among the very few crystalline silicic acids whose structures have been determined and confirmed based on a structure refinement. The structure of HH-Apo contains thin silicate monolayers that can be regarded as constructed by rings of interconnected [SiO3OH] tetrahedra which form a puckered silicate layer. A sheet of water molecules is intercalated between the silicate layers. There are no direct hydrogen bonds between the silanol groups, but there are hydrogen bonds of different strengths between the terminal O atoms of the silicate layers and the intercalated water molecules. The 1H MAS NMR spectrum presents a strong signal at 4.9 ppm related to the aforementioned bonds and interactions between the water molecules, as well as a small signal at 22.5 ppm corresponding to an extremely strong hydrogen bond with d(O… O) ≈ 2.2 Å. The structure of H-Car is free of structural water and consists exclusively of microporous silicate double-layers with 4-connected [SiO4] and 3-connected [SiO3OH] tetrahedra in a ratio of 1:1 and a thickness of 9.2 Å. Neighboring layers are connected to each other by medium–strong hydrogen bonds with O…O distances of 2.56 Å. The structure of HH-Apo decays within several hours while H-Car is stable. A topotactic condensation reaction applied to H-Car forms an irregularly condensed silicate which still contains the layers in a distorted form as building blocks.

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“…Magadiite (MAG) is a kind of layered silicate material [19,20] that possesses a large amount of potentially exchangeable hydrated sodium ions between its layers [21]; for this reason, MAG has unique properties, such as high surface area, good ion exchange, and expansion [22,23]. MAG showed excellent adsorption performance on heavy metal ions and organic pollutants [24,25,26], although it was difficult to separate from the water after adsorption.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of Magadiite–Magnetite Nanocomposite with Its Sorption Performance Analyses on Removal of Methylene Blue from Aqueous Solutions

Zhu

et al. 2019

Polymers

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The magadiite–magnetite (MAG–Fe3O4) nanocomposite has great potential applications in the field of biomaterials research. It has been used as a novel magnetic sorbent, prepared by co-precipitation method. It has the dual advantage of having the magnetism of Fe3O4 and the high adsorption capacity of pure magadiite (MAG). MAG–Fe3O4 was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The results showed that Fe3O4 nanoparticles were deposited on the interlayer and surface of magadiite. MAG–Fe3O4 was treated as an adsorbent for methylene blue (MB) removal from aqueous solutions. The adsorption properties of MAG–Fe3O4 were investigated on methylene blue; however, the results showed that the adsorption performance of MAG–Fe3O4 improved remarkably compared with MA and Fe3O4. The adsorption capacity of MAG–Fe3O4 and the removal ratio of methylene blue were 93.7 mg/g and 96.2%, respectively (at 25 °C for 60 min, pH = 7, methylene blue solution of 100 mg/L, and the adsorbent dosage 1 g/L). In this research, the adsorption experimental data were fitted and well described using a pseudo-second-order kinetic model and a Langmuir adsorption isotherm model. The research results further showed that the adsorption performance of MAG–Fe3O4 was better than that of MAG and Fe3O4. Moreover, the adsorption behavior of MB on MAG–Fe3O4 was investigated to fit well in the pseudo-second-order kinetic model with the adsorption kinetics. The authors also concluded that the isothermal adsorption was followed by the Langmuir adsorption isotherm model; however, it was found that the adsorption of the MAG–Fe3O4 nanocomposite was a monolayer adsorption.

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Silylation of a crystalline silicic acid: an MAS NMR and porosity study

Cited by 46 publications

References 53 publications

Modified clay for the synthesis of clay-based nanocomposites

Modified clay for the synthesis of clay-based nanocomposites

Synthesis and Crystal Structures of Two Crystalline Silicic Acids: Hydrated H-Apophyllite, H16Si16O40 • 8–10 H2O and H-Carletonite, H32Si64O144

Preparation and Characterization of Magadiite–Magnetite Nanocomposite with Its Sorption Performance Analyses on Removal of Methylene Blue from Aqueous Solutions

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