Sampling and Analysis of KGa-1B Well-Crystallized Kaolin Source Clay

Pruett, Robert J.; Webb, Harold L.

doi:10.1346/ccmn.1993.0410411

Cited by 128 publications

(75 citation statements)

References 3 publications

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“…1). According to CMS Source Clay Physical/Chemical Data and as confirmed by our own microprobe energy-dispersive X-ray (EDX) analysis, KGa-1b consists of more than 95w % kaolinite, although anatase (TiO 2 ), Fe oxides, quartz, and micas are observed in trace abundances (Pruett and Webb, 1993). Pseudo-cubic hematite particles were synthesized by hydrolysis of ferric chloride (FeCl 3 ) solutions in NaOH according to the gel-sol method (54 g FeCl 3 , 21.6 g NaOH for particles with a side length of 900 nm, and 54 g FeCl 3 , 22.8 g NaOH for particles with a side length of 300 nm) described in Sugimoto et al (1993), Kandori et al (1992), and Sugimoto and Sakata (1992).…”

Section: Aerosol Generationmentioning

confidence: 88%

Experimental quantification of contact freezing in an electrodynamic balance

et al. 2013

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Heterogeneous nucleation of ice in a supercooled water droplet induced by external contact with a dry aerosol particle has long been known to be more effective than freezing induced by the same nucleus immersed in the droplet. However, the experimental quantification of contact freezing is challenging. Here we report an experimental method to determine the temperature-dependent ice nucleation probability of size-selected aerosol particles. The method is based on the suspension of supercooled charged water droplets in a laminar flow of air containing aerosol particles as contact freezing nuclei. The rate of droplet–particle collisions is calculated numerically with account for Coulomb attraction, drag force and induced dipole interaction between charged droplet and aerosol particles. The calculation is verified by direct counting of aerosol particles collected by a levitated droplet. By repeating the experiment on individual droplets for a sufficient number of times, we are able to reproduce the statistical freezing behavior of a large ensemble of supercooled droplets and measure the average rate of freezing events. The freezing rate is equal to the product of the droplet–particle collision rate and the probability of freezing on a single contact, the latter being a function of temperature, size and composition of the contact ice nuclei. Based on these observations, we show that for the types of particles investigated so far, contact freezing is the dominating freezing mechanism on the timescale of our experiment

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Section: Aerosol Generationmentioning

confidence: 88%

Experimental quantification of contact freezing in an electrodynamic balance

et al. 2013

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“…The kaolinite clay mineral used in this study was type KGa-1b, a low defect kaolinite, from Washington County, Georgia, USA (The Clay Minerals Society) [21][22][23]. X-ray diffraction (XRD) analysis showed no impurity phases accompanying the raw clay, confirming the high purity of this kaolinite, and the moisture content of the raw material of around 0.5% was eliminated by drying at 40 • C. The cation exchange capacity (CEC) was measured (at ERM, Poitiers) using ammonium acetate exchange [24], and found to be 0.07 meq/g.…”

Section: Materials Usedmentioning

confidence: 99%

Understanding Cationic Polymer Adsorption on Mineral Surfaces: Kaolinite in Cement Aggregates

Jacquet¹,

Geatches

Clark

et al. 2018

Minerals

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Abstract:We present a joint experimental and theoretical investigation into the adsorption of polycationic quaternary ammonium polymers on the clay mineral kaolinite. Within the cement and concrete manufacturing industries such polymers are used to improve the final product by inerting the adsorption capacity of the clay minerals for more expensive additives. The adsorption of the presently used polymer (FL22) was compared with both a similar variant, but without a hydroxyl group (Fl22mod) and uncharged polyvinyl alcohol (PVA). Experimental results show that adsorption of FL22 is higher than that of FL22mod at both pH 6 and at pH > 10 and that the adsorption of PVA is the highest. Theoretical density functional theory (DFT) results and simplified models consisting of the basal surfaces of kaolinite, with monomers of FL22, FL22mod and PVA gave monomer coverage per unit surface area of kaolinite, a comparison of the configurations of the relaxed models, formation energies and Mulliken charges. These results show that the polycationic polymers interact with the basal surfaces of kaolinite electrostatically, explaining the high affinity of these polymers for kaolinite surfaces in the experimental results. The hydroxyl groups of FL22 and PVA form hydrogen bonds with the basal surfaces of kaolinite in conditions of pH 6. The joint experimental and theoretical results suggest that, due to the presence of the hydroxyl group, the conformation of FL22 changes under pH, where at neutral pH it lies relatively flat to the kaolinite surfaces, but at higher pH, conformational changes of the polymer occur, thereby increasing the adsorbed quantity of FL22.

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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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Sampling and Analysis of KGa-1B Well-Crystallized Kaolin Source Clay

Cited by 128 publications

References 3 publications

Experimental quantification of contact freezing in an electrodynamic balance

Experimental quantification of contact freezing in an electrodynamic balance

Understanding Cationic Polymer Adsorption on Mineral Surfaces: Kaolinite in Cement Aggregates

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

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