title: The Electrical Double Layer at Hydrous Manganese Dioxide/Electrolyte Interface.
abstract: The interfacial properties of two hydrous oxides of manganese, namely an amorphous variety and a poorly crystalline synthetic birnessite, in different electrolyte media, have been studied by using a batch potentiometric titration procedure with a 72-h equilibration period. The data obtained by this procedure are more relevant to a natural water system than those obtained by the rapid titration method as reported earlier [J. Colloid Interface Sci. 131, 103 (1989).]. Although the points of zero charge do not show any major variations, the surface dissociation and complexation (with Na(+) in NaCl) constants differ with the method of titration. Both of the samples are characterized by their high surface charge (low DeltapK(a)) and surface potential, and as a result, complexation takes place possibly within the inner helmholtz plane. It is concluded that the triple-layer model is not applicable to this colloid system and that a basic Stern model would be more suitable in this case. Copyright 2001 Academic Press.
authors.affiliation: Regional Research Laboratory, Bhubaneswar, Orissa, 751 013, India
authors.forename: Sushree Swarupa
authors.initials: SS
authors.lastname: Tripathy
authors.forename: Sukriti Bhusan
authors.initials: SB
authors.lastname: Kanungo
authors.forename: Santosh Kumar
authors.initials: SK
authors.lastname: Mishra