title: Distribution of hexavalent Cr species across the clay mineral surface-water interface.
abstract: The adsorption isotherms of Cr(VI) on kaolinite, montmorillonite, and alumina were adequately treated with Langmuir model showing behavior characteristic of single-layer adsorption. The efficiency of the adsorbents in removing Cr(VI) from water follows the order alumina > kaolinite > montmorillonite > silica. Speciation studies indicate that hydrogen chromate ions were the major adsorbed species and simultaneous adsorption of dichromate ion occurred at concentrations greater than approximately 10(-3) mol L(-1). It is most probable that the mechanism of adsorption of the hydrogen chromate ion at the surface of alumina is predominantly electrostatic adsorption, with outer sphere complex formation.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil.
authors.forename: Mauricia B
authors.initials: MB
authors.lastname: Fritzen
authors.forename: Aloisio J
authors.initials: AJ
authors.lastname: Souza
authors.forename: Tiago A G
authors.initials: TA
authors.lastname: Silva
authors.forename: Luciana
authors.initials: L
authors.lastname: Souza
authors.forename: Rene A
authors.initials: RA
authors.lastname: Nome
authors.forename: Haidi D
authors.initials: HD
authors.lastname: Fiedler
authors.forename: Faruk
authors.initials: F
authors.lastname: Nome