The electrokinetic and adsorption characteristics of alumina suspensions in the presence of Darvan C as dispersant have been investigated. The interaction of Darvan C with alumina has been interpreted in terms of electrokinetic and adsorption measurements. The adsorption density of Darvan C increases greatly with decreasing pH. The isoelectric point (iep) of the sample under investigation is found to be located at pH 9.1. For pH values near and below the point of zero charge, there is an added electrostatic attractive potential for adsorption, which results in high-affinity adsorption behavior. Possible mechanisms of interaction between alumina and Darvan C are described and discussed. (c) 2005 Elsevier Inc. All rights reserved.