External surface structure of organoclays analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy in combination with molecular dynamics simulations

Schampera, Birgit; Tunega, Daniel; Šolc, Roland; Woche, Susanne K.; Mikutta, Robert; Wirth, Richard; Dultz, Stefan; Guggenberger, Georg

doi:10.1016/j.jcis.2016.06.008

Cited by 43 publications

(39 citation statements)

References 48 publications

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“…The results show a successive transformation of the organic coating from thin disordered monolayers at low, up to disordered bilayer or quasi paraffin‐type arrangements at high coverage. Moreover, the thickness of the organic coatings obtained from simulations are in good agreement with the estimated thickness (1–2.5 nm) from transmission electron microscopy images ( Schampera et al., ).…”

Section: Approaches To Analyze Mineral–organic Associationssupporting

confidence: 82%

“…Molecular dynamics simulations were applied by Schampera et al. () to study the adsorption and distribution of alkylammonium cations (hexadecylpyridinium and hexadecyltrimethylammonium) on the basal surface of montmorillonite. The results show a successive transformation of the organic coating from thin disordered monolayers at low, up to disordered bilayer or quasi paraffin‐type arrangements at high coverage.…”

Section: Approaches To Analyze Mineral–organic Associationsmentioning

confidence: 99%

“…At small OM loadings, the hydrophobic groups are arranged at the outside of the particle, while at high OM loading, another layer of organic molecules can be attached to the adsorbed OM with upright orientation via hydrophilic functional groups, thus resulting in hydrophobic groups oriented towards the outside. Such change in surface wettability coupled to the orientation of organic molecules, including loadings exceeding the mineral's sorption capacity, has been demonstrated for polymeric N-containing organic cations (hexadecyltrimethyl ammonium and hexadecyl pyridinium) sorbed to montmorillonite (Schampera et al, 2016). However, for natural systems the different orientation of organic molecules might be explained by their polyelectrolytic character as well, i.e., larger molecules can re-arrange under variable water contents.…”

Section: Soil Wettabilitymentioning

confidence: 99%

“…Computer modeling is useful in investigating the three-dimensional structure of soil OM, metal-OM complexes, and MOA, of which the properties like surface area, polarity, and stability can be estimated by minimizing the potential energy of conformations via geometric optimization. Molecular modeling coupled with computational chemistry can help to understand the formation and dynamic process of MOA and the involved mechanisms (Schulten and Leinweber, 2000;Sutton and Sposito, 2006;Schaumann and Thiele-Bruhn, 2011;Schampera et al, 2015Schampera et al, , 2016. However, molecular models only represent a simplified reality.…”

Section: Theoretical and Modeling Approachesmentioning

confidence: 99%

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The multilayer model of soil mineral–organic interfaces—a review

Gao

Mikutta

Jansen

et al. 2019

J. Plant Nutr. Soil Sci.

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Association of organic matter (OM) with minerals is an important pathway in the formation of stable OM in soil. While the importance of mineral-organic associations (MOA) in regulating soil carbon cycling has been rigorously demonstrated by empirical evidence, knowledge about the molecular-scale arrangement of OM at mineral surfaces is still lacking. Such knowledge is urgently needed to disentangle the mechanisms of long-term storage of soil OM. Based on indirect observations regarding the formation, composition, and structure of MOA, a conceptual multilayer model was proposed by Kleber et al. in 2007 to foster debate and help elucidating the structure and reactivity of MOA. According to this model, the associated OM at mineral surfaces is discrete and self-organized into a multilayer structure. In this review, we aim to collect and evaluate existing studies that used this model to explain biogeochemical processes at mineral-organic interfaces, and based on this, assess the applicability of the model. The multilayer model has seen extensive adoption within soil science and related fields. In general, existing studies either support the concept of a patchy distribution of adsorbed OM on mineral surfaces or advocate that OM can be coprecipitated with nanosized poorly crystalline minerals or hydrolysable metals. However, the evidence for the patchy distribution of adsorbed OM cannot support the multilayer model on its own. There is little consensus about the role of N-rich OM in forming the contact zone according to the multilayer model but surface conditioning by different classes of organic compounds appears to be an essential factor for the overall adsorption of OM. Nevertheless, large uncertainty still remains with respect to multilayer-like organization of MOA. By taking advantage of recent developments in surface analytical sciences and computational chemistry, a rigid experimental testing of the multilayer model at the molecular level is still required and awaits to be integrated into improved concepts of MOA formation and OM stabilization.

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Section: Approaches To Analyze Mineral–organic Associationssupporting

confidence: 82%

Section: Approaches To Analyze Mineral–organic Associationsmentioning

confidence: 99%

Section: Soil Wettabilitymentioning

confidence: 99%

Section: Theoretical and Modeling Approachesmentioning

confidence: 99%

See 2 more Smart Citations

The multilayer model of soil mineral–organic interfaces—a review

Gao

Mikutta

Jansen

et al. 2019

J. Plant Nutr. Soil Sci.

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“…The reason is that the size of alkyl ammonium cation increases with the increase of carbon chain length, when Na-MT is modified by alkyl ammonium with long carbon chain, the d (001) of C n -MT1 will evidently increase due to the spatial volume effect. Previous studies also found similar conclusions [11,30,31]. But the d (001) values acquired by us are obviously higher than that obtained by Brito et al [32], this difference may be mainly caused by different modification method, drying time and layer charge density of Na-MT.…”

Section: Ftir Measurementsupporting

confidence: 85%

Comprehensive Characterization of the Structure and Gel Property of Organo-Montmorillonite: Effect of Layer Charge Density of Montmorillonite and Carbon Chain Length of Alkyl Ammonium

et al. 2020

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In this work, the effect of layer charge density of Na-montmorillonite (Na-MT) and carbon chain length of alkyl ammonium on the structure and gel property of organo-montmorillonite (organo-MT) was studied by using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TG) analysis, contact angle test, molecular dynamics (MD) simulation, and gel apparent viscosity determination experiment. The results of XRD show that Na-MT with lower layer charge density is easier to swell after intercalation of alkyl ammonium, and the basal spacing of organo-MT increases with the increase of carbon chain length. The results of FTIR show that the absorption bands at 2924 cm −1 and 2853 cm −1 shift towards low frequency region with the increase of carbon chain length, and the absorption bands at 515 cm −1 and 463 cm −1 move towards high frequency region when the layer charge density increases. The mass loss of organo-MT evidently increases with the increase of layer charge density of Na-MT or carbon chain length of alkyl ammonium. The contact angle test results are well in line with the TG data and reveal that alkyl ammonium with longer carbon chain can significantly improve the hydrophobicity of organo-MT. MD simulation indicates that, when the layer charge density is low, the distribution of alkyl ammonium gradually changes from parallel double layers to partially inclined distribution with the increase of carbon chain length, but when the layer charge density is high, the distribution of alkyl ammonium gradually changes from three layers into four layers. The test results of the apparent viscosity of the gel formed by organo-MT in xylene show that the apparent viscosity of organo-MT gel is negatively correlated with the layer charge density of Na-MT and positively correlated with the carbon chain length of alkyl ammonium. ability in aqueous solution, MT has attracted wide attention both in academia and in industry [3][4][5][6]. The occurrence of non-equivalent isomorphic substitution of Al 3+ for Si 4+ in the tetrahedral sheets and Mg 2+ for Al 3+ in the octahedral layers makes MT layers negatively charged [7]. To balance the negative layer charge density of MT, some hydrophilic exchangeable cations, such as Na + , K + , and Ca 2+ , are usually attracted into the interlayer domain, and due to the hydration of inorganic cation [8,9], confined basal spacing, and high surface energy, natural MT performs badly in organic phase environment [6,10].In order to expand the application of MT in industry, organo-MT is synthesized by intercalating surfactant into interlayer space of natural MT [11]. In this way, interlayer distance of MT obviously increase and new sorption sites can be formed [12], besides, inorganic cation can be exchanged by surfactant, which results in that the surface property of MT converts from hydrophilic to hydrophobic. As a result, the organo-MT can be applied in many fields, such as polymer MT nanocomposite [13,14], adsorbent for organic contaminant [15,16], oil-based drilling fluid [17], ...

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Molecular dynamics simulation and experimental study of micro‐structure and gel properties of single chain alkyl ammonium intercalated Na‐montmorillonite

Qiu

Chen

Cao

et al. 2022

J of Applied Polymer Sci

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The synergistic effect of layer charge density of Na-montmorillonite (Na-MT), the carbon chain length and the dosage of alkyl ammonium on the microstructure and gel properties of single chain alkyl ammonium intercalated Na-MT was systematically studied by using X-ray diffraction (XRD), molecular dynamics simulation and small-scale experiment. The results of Z-axis density distribution and radial distribution function (RDF) shows that with the increase of the dosage of alkyl ammonium, the distribution pattern is gradually changed from layered to inclined winding and stacking distribution. The results of the self-diffusion coefficient show that the higher the layer charge density of Na-MT, the shorter the length of alkyl ammonium carbon chain, the lower the diffusivity of each component in the inter-layer. With the increase of the dosage of alkyl ammonium, the diffusivity of alkyl ammonium in the inter-layer increases firstly and then decreases. The results of gel properties show that with the increase of the dosage of alkyl ammonium, the colloidal ratio of the alkyl ammonium/Na-MT in xylene gradually increases, while the apparent viscosity in xylene-ethanol increases firstly and then decreases. Furthermore, the longer the carbon chain of alkyl ammonium, the lower the layer charge density of MT, the better the gel properties of the prepared alkyl ammonium/Na-MT.

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External surface structure of organoclays analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy in combination with molecular dynamics simulations

Cited by 43 publications

References 48 publications

The multilayer model of soil mineral–organic interfaces—a review

The multilayer model of soil mineral–organic interfaces—a review

Comprehensive Characterization of the Structure and Gel Property of Organo-Montmorillonite: Effect of Layer Charge Density of Montmorillonite and Carbon Chain Length of Alkyl Ammonium

Molecular dynamics simulation and experimental study of micro‐structure and gel properties of single chain alkyl ammonium intercalated Na‐montmorillonite

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