title: Sorptive uptake of selenium with magnetite and its supported materials onto activated carbon.
abstract: Kinetic and equilibrium uptake studies of selenite in aqueous solution with synthetic magnetite (Mag-P), commercial magnetite (Mag-C), goethite, activated carbon (AC), and a composite material containing 19% magnetite supported on activated carbon (CM-19) were investigated. Kinetic uptake studies used a one-pot setup at pH 5.26 at variable temperature. Sampling of unbound selenite in-situ was achieved with analytical detection by atomic absorbance. The sorptive uptake at equilibrium and kinetic conditions are listed in descending order: goethite>Mag-P>Mag-C>CM-19. Kinetic uptake parameters reveal that Mag-P showed apparent negative values for the activation energy (E(a)) and the enthalpy of activation (ΔH(‡)), in agreement with a multi-step process for the kinetic uptake of selenite. By contrast, Mag-C, CM-19, and goethite showed positive values for E(a) and ΔH(‡). The uptake properties of the various sorbent materials with selenite are in accordance with the formation of inner- and out-sphere complexes. Leaching of iron from the composite material (CM-19) was attenuated due to the stabilizing effect of the magnetite within the pore sites and the surface of AC. Supported iron oxide nanomaterial composites represent a unique sorbent material with tunable uptake properties toward inorganic selenite in aqueous solution.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
authors.forename: Jae H
authors.initials: JH
authors.lastname: Kwon
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada. Electronic address: lee.wilson@usask.ca.
authors.forename: Lee D
authors.initials: LD
authors.lastname: Wilson
authors.affiliation: Saskatchewan Structural Science Centre, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Sammynaiken
keywords: Adsorption; Goethite; Kinetics; Magnetite; Selenite; Sorption kinetics; Supported material