On using electrokinetics to interpret the flotation and interfacial behavior of manganese dioxide

The point of zero charge of manganese dioxide plays an important role in it s flotation with physisorbing but not with chemisorbing collectors. Detaile d flotation studies with oleate as the collector indicate two flotation and adsorption peaks in this system. The peak at low pH's appears to result fr om physisorption of oleate ions together with coadsorption of oleic acid mo lecules on the positively charged solid. At alkaline pH's, there is a secon d adsorption peak which must result from strong chemical interaction of ole ate with the negatively charged surface. Electrokinetic experiments clearly indicate that oleate ions are the active collector species at both peaks. A procedure is proposed for estimating collector adsorption from electrokin etic data. (C) 1999 Published by Elsevier Science B.V. All rights reserved.