Colloid Clay Science

Lagaly, G.; Dékány, Imre

doi:10.1016/b978-0-08-098258-8.00010-9

Cited by 108 publications

(66 citation statements)

References 319 publications

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“…EF and EE associations, on the other hand, lead to three dimensional "house of cards" structures where the volume occupied or swept out by an individual particle is maximized, and the apparent volume fraction of the suspension is also a maximum. This results in more rheologically complex suspensions than would occur with FF association [2,13]. The realignment from one form of particle association to another has traditionally been attributed to electrostatic attractive and repulsive forces between the edges and faces.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Characterisation of kaolinite colloidal and flow behaviour via crystallinity measurements

Ndlovu¹,

Farrokhpay²,

Forbes³

et al. 2015

Powder Technology

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Please cite this article as: Bulelwa Ndlovu, Saeed Farrokhpay, Elizaveta Forbes, Dee Bradshaw, Characterisation of kaolinite colloidal and flow behaviour using its crystallinity measurements, Powder Technology (2014Technology ( ), doi: 10.1016Technology ( /j.powtec.2014 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractThis study evaluates the possibility of predicting colloidal and flow behaviour of kaolinite suspensions by measuring kaolinite crystallinity. The Hinckley index of different samples was calculated from XRD spectra as an indicator of the crystallinity. Kaolinite samples with a high Hinckley index showed a defined platy morphology with smooth surfaces of low surface area, while progressively roughened basal planes with prevalent broken edges were observed in kaolinite samples of lower Hinckley indices. Despite similarity in the elemental composition, the kaolinite samples present different surface charge properties, likely due to variations in exposed pH dependent edge sites. Poorly crystallised kaolinite samples were characterised by higher yield stresses and viscosities. This study highlights the importance of crystallinity characterisation towards predicting colloidal behaviour and flow characteristics of kaolinite suspensions.

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Characterisation of kaolinite colloidal and flow behaviour via crystallinity measurements

Ndlovu¹,

Farrokhpay²,

Forbes³

et al. 2015

Powder Technology

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“…Clays are well characterized for their colloidal properties in water based systems and are used in many industrial applications [21]. A detailed statistical approach was followed to evaluate the variations that sampling may create in particle size analysis.…”

Section: Introductionmentioning

confidence: 99%

Particle size analysis on wide size distribution powders; effect of sampling and characterization technique

Basim

Khalili

2015

Advanced Powder Technology

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“…The permanent negative charge of the remaining aluminosilicate, as in the case of illite clay minerals (Jiang et al, 2012), determines the ME properties of WDC DCB400 .The d z values of WDC DCB400 samples increased compared with that of WDC CB400, supporting the expansion of aggregate size due to electrostatic repulsion between negatively charged aluminosilicate residues. A possible aggregation of dispersed clay minerals through edge/plate (cardhouse structure) contacts (Lagaly et al, 2006;Jiang et al, 2012) under low ionic strength conditions may also increase d z and the porosity. These colloidal results obtained on a micrometer scale can thus be directly related to k (SAXS), and R p (N 2 gasadsorption) results on a nanometer scale, also demonstrating a corresponding increase of the porous mineral matrix structure for the WDCs after the removal of metal oxide nanoparticles.…”

Section: Contribution Of Metal Oxide Nanoparticles To the Colloidal Pmentioning

confidence: 99%

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

et al. 2014

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Abstract:The surface area and pore structure of easily dispersed soil particles < 2 µm in size (water-dispersible colloids, WDCs) are important for carbon sequestration and transport in soil. Two processes are essential for the terrestrial carbon cycling. In this work, we determine the effects of dithionite-citrate-bicarbonate (DCB) extractable metal oxides, and oxalate extractable metal oxides on the specific surface area (SSA) and pore structure of WDCs from silt loam topsoils of three TERENO test sites with a similar clay content (20%) in Germany (arable (Selhausen), grassland (Rollesbroich) and forest (Wuestebach) soils). The N 2 gasadsorption (−196°C), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and microelectrophoretic (ME) methods were used and compared. Results show that 1) the SSA of the WDCs from Selhausen, Rollesbroich, and Wuestebach decreased more after DCB treatment (27%, 35%, and 44%) than after oxalate treatment (5%, 14%, and 22%). DCB removed metal oxide nanoparticles from WDCs were found to have diameters (d p ) ranging from 4 nm to 8 nm and the surface loading ratios on the surface of aluminosilicate residues in WDCs were estimated to be 11% to 22% for three soils where the highest value was found in the acidic forest soil. 2) Pore sizes in the mesopore range (2 nm to 50 nm) were analyzed in the WDC fractions. The results were discussed in terms of accessible open pores for the pristine WDCs and WDC samples from which metal oxide nanoparticles and organic carbon (OC) had been removed. The lower average pore radius (R p ) measured by the N 2 gasadsorption method based on the total volume (V t ) to SSA ratio variations in WDCs without metal oxides compared to WDC with metal oxides indicated a contraction of the porous structure of WDCs due to the presence of metal oxide nanoparticles. The pore size distribution (PSD) analysis showed a sensitive contribution of metal oxide nanoparticles in the low range of pore sizes (< 25 nm) of WDCs. In SAXS measurements, higher surface fractal dimensions (D s ) were observed in WDCs before the metal oxides removal, which supports a roughness increase of the interfaces in the presence of nanoparticles. The colloidal characterization of WDCs by the DLS and ME methods shows, at a µm scale, the role of positively charged metal oxide nanoparticles in forming WDCs with a more compact structure by decreasing the particle size (d z ) and the negative zeta potential (ζ).3) The comparison of R p , k, d z and d p results between different soils also indicates the dependence on the clay mineralogy of WDCs so that the heterocoagulation between kaolinite and illite (clay minerals of different aspect ratios) increases the size of soil mesopores (Rollesbroich). In conclusion, the results of this study clearly show that the combination of the N 2 gas-adsorption, SAXS, DLS and ME methods allows the characterization of soil porosity in the nanometer range where metal oxide nanoparticles contribute to a more compact structure of WDC.

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Colloid Clay Science

Cited by 108 publications

References 319 publications

Characterisation of kaolinite colloidal and flow behaviour via crystallinity measurements

Characterisation of kaolinite colloidal and flow behaviour via crystallinity measurements

Particle size analysis on wide size distribution powders; effect of sampling and characterization technique

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

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