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Filtration of precipitated silica aggregates: Length scales, percolation threshold and yielding behaviour

Ragueh, Deka Moussa and Meireles, Martine and Cabane, Bernard and Gummel, Jérémie Filtration of precipitated silica aggregates: Length scales, percolation threshold and yielding behaviour. (2015) Separation and Purification Technology, vol. 156 (n° 1). pp. 2-11. ISSN 1383-5866

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Official URL: http://dx.doi.org/10.1016/j.seppur.2015.10.005

Abstract

Reinforcing precipitated silica systems have a complex hierarchical structure consisting of a branched network made of connected clusters composed of small silica beads welded together into larger dense aggregates. Here, we study the evolution of such structural features during a filtration process. The typical behaviour is that the cakes formed at constant pressure do not reorganize at local scale during a filtration experiment. Accordingly, the creep resistance of a precipitated silica network is high. Overall, there is a percolation threshold, which appears when the branches are pushed into each other. Once this percolation path is reached, the cake withstands compression over more than a decade of applied pressure. Beyond, it seemed useful to make predictions of the filtration properties knowing the typical length scales – small silica beads, dense aggregates, and consolidation behaviour of the cake. A simple approach introducing the concept of an effective medium approximation into Darcy’s law was tested. This approach treats the network as a pseudo-continuum of porous medium built at two main length scales: the size of dense aggregates and a length scale representing the typical distance between the aggregates. The quality of the fit of experimental filtration rates by this simple model indicates that a description based on a continuous network made of two material phases is accurate.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Separation and Purification Technology website : http://www.sciencedirect.com/science/article/pii/S1383586615302562
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Ecole Supérieure de Physique et de Chimie Industrielles - ESPCI (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Martine MEIRELES
Deposited On:29 Feb 2016 11:22

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