Electrokinetic clarification of colloidal suspensions

Citation
Tj. Johnson et Ej. Davis, Electrokinetic clarification of colloidal suspensions, ENV SCI TEC, 33(8), 1999, pp. 1250-1255
Citations number
20
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Journal title
ENVIRONMENTAL SCIENCE & TECHNOLOGY
ISSN journal
0013936X → ACNP
Volume
33
Issue
8
Year of publication
1999
Pages
1250 - 1255
Database
ISI
SICI code
0013-936X(19990415)33:8<1250:ECOCS>2.0.ZU;2-X
Abstract
A novel apparatus has been developed for the electrophoretic clarification of concentrated colloidal suspensions. The laboratory equipment is capable of being scaled up to much larger capacity. The apparatus was designed to p rocess suspensions in either batch or semicontinuous operation, and it has been used to demonstrate the removal of coal/clay colloidal matter from the effluent of a coal-washing facility. In addition, a parametric study of so dium-bentonite suspensions in batch operation was performed to elucidate th e effects of initial colloid and electrolyte (NaCl) concentrations on the r ate of clarification and the instantaneous power requirements. It was found that an increase in either the initial particle or electrolyte concentrati on (up to 50 mg of NaCl/L) caused a decrease in the instantaneous power lev els but increased the time necessary to reach a given solution clarificatio n. Typical electrophoretic clarification experiments resulted in 99.9% remo val of the colloidal matter. In semicontinuous operation it was shown that a 0.2 wt % sodium-bentonite suspension could he clarified to 2.6 x 10(-4) w t % in 13.5 h without the addition of flocculants or other chemicals.