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Distinction between Electrostatic and Electrokinetic Effects on the Permeability of Colloidal Packed Beds
Author(s) -
Schäfer B.,
Nirschl H.
Publication year - 2005
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200500079
Subject(s) - electrokinetic phenomena , permeability (electromagnetism) , ionic strength , electrostatics , colloid , suspension (topology) , streaming current , agglomerate , chemistry , chemical engineering , particle size , colloidal particle , materials science , nanotechnology , composite material , membrane , aqueous solution , biochemistry , mathematics , homotopy , pure mathematics , engineering
Electrostatic and electroviscous effects can significantly decrease the permeability of packed beds which consist of colloidal particles. This results in poor filterability of colloidal suspensions. Electrostatic effects refer to the dependency of the structure of the packed bed on the particles' tendency to agglomerate or disagglomerate. This tendency is influenced by the particle charge, and thus the pH and the ionic strength of the suspension. Electroviscous effects relate to the increased flow resistance of the pores due to a streaming potential being established when the electrochemical double layer of the particles is sheared off. It is difficult to distinguish electrostatic and electroviscous effects because they are interrelated. The comparison of permeability measurements of both TiO 2 and Al 2 O 3 with a classical permeability model demonstrates the influence of the two different effects on permeability.