The distortion of the diffuse double layer and its effect on flow properties of dense flyash slurries

Iyer, R. S. and Stanmore, B. R. (2000) The distortion of the diffuse double layer and its effect on flow properties of dense flyash slurries. Colloids and Surfaces A: Physicochemical Engineering Aspects, 166 1-3: 133-144. doi:10.1016/S0927-7757(99)00485-9


Author Iyer, R. S.
Stanmore, B. R.
Title The distortion of the diffuse double layer and its effect on flow properties of dense flyash slurries
Journal name Colloids and Surfaces A: Physicochemical Engineering Aspects   Check publisher's open access policy
ISSN 0927-7757
Publication date 2000-06-15
Sub-type Article (original research)
DOI 10.1016/S0927-7757(99)00485-9
Volume 166
Issue 1-3
Start page 133
End page 144
Total pages 12
Place of publication Amsterdam, Netherlands
Publisher Elseiver
Language eng
Subject 0306 Physical Chemistry (incl. Structural)
Abstract Flyashes obtained from power stations burning pulverised Curragh and Tarong coals were air classified to obtain a fine fraction (- 10 mu m). When dense aqueous slurries of these fines were subjected to rheological measurement in a rotating viscometer, the two ashes exhibited different packing propensities. In interpreting the experimental flow data, a new volumetric packing factor Phi was defined to include the volume of the diffuse double layer. When the Krieger-Dougherty equation was fitted to the data, the maximum packing fraction (Phi(m)) redesignated as the quasi-maximum packing fraction was found to vary at low shear rates. It is proposed that the differences in rheological behaviour and variation in Phi(m) is due to the surface chemistry of fine particles. The two flyashes produce leachates of different ionic strength and hence generate different thicknesses of diffuse double layer. Shearing at close packing produces distortion in the diffuse double layer, especially in dilute leachates with thick diffuse double layers. A particle packing model based on the unit cell is proposed to quantify the distortion of the diffuse double layer, and to explain its influence on Phi(m) and flow behaviour. (C) 2000 Elsevier Science B.V. All rights reserved
Keyword diffuse double layer
flow properties
fly ashes
dense slurries
distortion
concentrated suspensions
rheology
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemical Engineering Publications
 
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