Alteration of non-swelling clay minerals and magadiite by acid activation

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

doi:10.1016/j.clay.2009.02.001

Cited by 98 publications

(44 citation statements)

References 29 publications

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“…This is similar to previous BET measurements of 94 m 2 g −1 for NX illite (Steudel et al, 2009), and a value of 112.8 ± 0.7 m 2 g −1 for natural illite samples (Alvarez-Puebla et al, 2005). However, Steudel et al (2009) found that micro-pores contributed 14 % of the specific surface area in their sample of NX illite, which may mean that our value of 104.2 m 2 g −1 is an overestimate. In that case, we would underestimate the ice-nucleating ability of NX illite, although this uncertainty is minor in comparison to that from the droplet size distribution.…”

Section: Characterisation Of Nx Illitesupporting

confidence: 90%

“…For example, we found that there was 61 % illite rather than Arginotec's value of 86 %. Möhler et al (2008) also used NX illite, which was quoted as being 77 % illite, and Steudel et al (2009) report an illite content of 76 %. This suggests that NX illite may be a variable material, which is possibly not surprising as it is a natural product.…”

Section: Characterisation Of Nx Illitementioning

confidence: 99%

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Immersion mode heterogeneous ice nucleation by an illite rich powder representative of atmospheric mineral dust

et al. 2012

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Abstract. Atmospheric dust rich in illite is transported globally from arid regions and impacts cloud properties through the nucleation of ice. We present measurements of ice nucleation in water droplets containing known quantities of an illite rich powder under atmospherically relevant conditions. The illite rich powder used here, NX illite, has a similar mineralogical composition to atmospheric mineral dust sampled in remote locations, i.e. dust which has been subject to long range transport, cloud processing and sedimentation. Arizona Test Dust, which is used in other ice nucleation studies as a model atmospheric dust, has a significantly different mineralogical composition and we suggest that NX illite is a better surrogate of natural atmospheric dust.Using optical microscopy, heterogeneous nucleation in the immersion mode by NX illite was observed to occur dominantly between 246 K and the homogeneous freezing limit. In general, higher freezing temperatures were observed when larger surface areas of NX illite were present within the drops. Homogenous nucleation was observed to occur in droplets containing low surface areas of NX illite. We show that NX illite exhibits strong particle to particle variability in terms of ice nucleating ability, with ∼1 in 10 5 particles dominating ice nucleation when high surface areas were present. In fact, this work suggests that the bulk of atmospheric mineral dust particles may be less efficient at nucleating ice than assumed in current model parameterisations.For droplets containing ≤2×10 −6 cm 2 of NX illite, freezing temperatures did not noticeably change when the cooling rate was varied by an order of magnitude. The data obtained during cooling experiments (surface area ≤2×10 −6 cm 2 ) is shown to be inconsistent with the single component stochastic model, but is well described by the singular model (n s (236.2 K≤T ≤247.5 K) = exp(6.53043×10 4 − 8.2153088. However, droplets continued to freeze when the temperature was held constant, which is inconsistent with the time independent singular model. We show that this apparent discrepancy can be resolved using a multiple component stochastic model in which it is assumed that there are many types of nucleation sites, each with a unique temperature dependent nucleation coefficient. Cooling rate independence can be achieved with this time dependent model if the nucleation rate coefficients increase very rapidly with decreasing temperature, thus reconciling our measurement of nucleation at constant temperature with the cooling rate independence.

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Section: Characterisation Of Nx Illitesupporting

confidence: 90%

Section: Characterisation Of Nx Illitementioning

confidence: 99%

Immersion mode heterogeneous ice nucleation by an illite rich powder representative of atmospheric mineral dust

et al. 2012

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“…AFM has been used to study minerals, but it is time consuming to analyze a sufficient number of particles with this technique and it can miss some of the interior detail (Bickmore et al 2002;Metz et al 2005). The major 716 method used for minerals is the measurement of BrunauerEmmett-Teller (BET) surface area, where the adsorption of a nonreactive gas to the surface of the particles is used to determine the surface area (Brunauer et al 1938;Madsen 1977;van Olphen and Fripiat 1979;Pruett and Webb 1993;Bereznitski et al 1998;Schuttlefield et al 2007;Steudel et al 2009;Sanders et al 2010;Broadley et al 2012). BET measurements can show variability for particles depending on the gas used with up to a 37% difference shown between N 2 and Kr adsorption (Brantley and Mellott 2000).…”

Section: Introductionmentioning

confidence: 99%

Facile Method for Determining the Aspect Ratios of Mineral Dust Aerosol by Electron Microscopy

Veghte

Freedman

2014

Aerosol Science and Technology

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Mineral dust is the second largest atmospheric emission by mass and one of the least understood sources. The shape of the particles depends on their composition and has implications for particle optical properties and reactive surface area. Mineral dust particles are often approximated as spheroids to model their optical properties. In this study, scanning electron microscopy (SEM) is used to measure the aspect ratios of calcite, quartz, NXillite, kaolinite (KGa-1b and KGa-2), and montmorillonite (STx1b and SWy-2). In addition to traditional SEM images of the top of the particles, the SEM substrates are oriented approximately normal to the electron beam in order to image the side of the particles. In this manner, aspect ratios for the top and side orientation of the particles are determined. Calcite particles have an aspect ratio of approximately 1.3 in both orientations, while quartz particles have an aspect ratio of 1.38 in the top orientation and 1.64 in the side orientation. The clay minerals studied all exhibited plate-like structures with aspect ratios of 1.35 to 1.44 for the top orientation and 4.80 to 9.14 for the side orientation. These values are used to estimate the specific surface areas (SSAs) of the minerals, which are compared to BrunauerEmmett-Teller (BET) surface area measurements. Through this study, we present a simple method for determining the aspect ratios of aerosolized samples, rather than relying on literature values of model systems. As a result, this technique should provide a better method for determining the optical properties of mineral dust particles.

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“…Based on the advantage in using natural minerals, the chemically modified clay surface has received great attention not only due to the new synthetic materials, but also due to their expressive applications. Thus, organoclays are essential in developing polymer nanocomposites, that constitutes one of the most developed areas of nanotechnology 9,10 , mainly when the investigation is focused on the organofunctionalization of lixiviated vermiculite. Selective leaching of minerals from clay treated with acid is a simple procedure for preparing porous silica.…”

Section: Introductionmentioning

confidence: 99%

Inorganic-organic hybrids originating from organosilane anchored onto leached vermiculite

2013

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The reactivity of clay minerals leached in grafting reactions was investigated. Precursor solids were prepared by treating the sodium vermiculites with nitric acid solutions at several concentrations. The lixiviation produced the restructured porous solids with surface area over a wide range, varying from 133 to 673 m 2 g -1 . The sodium and lixiviated vermiculites reacted covalently with silylating agent, 3-aminopropyltrimethoxysilane, to attach this agent onto the inorganic surface, through the free available silanols. The products were characterized by CNH elemental analysis, infrared spectroscopy, X-ray diffraction, nuclear magnetic resonance in the solid state for carbon and silicon. CHN data expressed by significant contents of anchored organic chains, up to 2.14 mmol g -1 , as the degree of leaching was increased. The success of this investigation is directly related to the leaching of the natural vermiculite, which is strongly influenced by the reactivity of the abundant original source.

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Alteration of non-swelling clay minerals and magadiite by acid activation

Cited by 98 publications

References 29 publications

Immersion mode heterogeneous ice nucleation by an illite rich powder representative of atmospheric mineral dust

Immersion mode heterogeneous ice nucleation by an illite rich powder representative of atmospheric mineral dust

Facile Method for Determining the Aspect Ratios of Mineral Dust Aerosol by Electron Microscopy

Inorganic-organic hybrids originating from organosilane anchored onto leached vermiculite

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