title: Adsorption of Cd2+ on carboxyl-terminated superparamagnetic iron oxide nanoparticles.
abstract: The affinity of Cd(2+) toward carboxyl-terminated species covalently bound to monodisperse superparamagnetic iron oxide nanoparticles, Fe(3)O(4)(np)-COOH, was investigated in situ in aqueous electrolytes using rotating disk electrode techniques. Strong evidence that the presence of dispersed Fe(3)O(4)(np)-COOH does not affect the diffusion limiting currents was obtained using negatively and positively charged redox active species in buffered aqueous media (pH = 7) devoid of Cd(2+). This finding made it possible to determine the concentration of unbound Cd(2+) in solutions containing dispersed Fe(3)O(4)(np)-COOH, 8 and 17 nm in diameter, directly from the Levich equation. The results obtained yielded Cd(2+) adsorption efficiencies of ~20 μg of Cd/mg of Fe(3)O(4)(np)-COOH, which are among the highest reported in the literature employing ex situ methods. Desorption of Cd(2+) from Fe(3)O(4)(np)-COOH, as monitored by the same forced convection method, could be accomplished by lowering the pH, a process found to be highly reversible.
authors.affiliation: Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, United States.
authors.forename: Zhange
authors.initials: Z
authors.lastname: Feng
authors.forename: Shun
authors.initials: S
authors.lastname: Zhu
authors.forename: Denis Ricardo
authors.initials: DR
authors.lastname: Martins de Godoi
authors.forename: Anna Cristina S
authors.initials: AC
authors.lastname: Samia
authors.forename: Daniel
authors.initials: D
authors.lastname: Scherson
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D008280:Magnetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010316:Particle Size
chemical_list: D002264:Carboxylic Acids; D005290:Ferric Compounds; D002104:Cadmium; C000499:ferric oxide