title: Adsorption of nickel ions by oleate-modified magnetic iron oxide nanoparticles.
abstract: In this work, magnetic nanoparticles of iron oxide (MNPs) were synthesized, and then the surface was recovered with an oleate double layer in order to investigate the ability of this material to adsorb nickel ions. First, the solution chemistry of oleate ions was investigated in order to determine the critical micellar concentration (CMC) value and the arrangements of ions above the CMC. Then, the synthesized oleate-modified MNP was characterized (TEM, DLS, XRD, FTIR, zeta potential, magnetometry). Finally, adsorption experiments were carried out as a function of pH and as a function of nickel concentration in 0.1 g L-1suspensions of oleate-modified MNP. The results show that CMC of oleate ranges from 1 to 2.5∙10-3mol L-1. Above CMC, arrangement of oleate ions as droplets, vesicles, or micelles depends on pH and influences the average size and solution absorbance. Potentiometric titrations allowed determining a pKa value of 7.8 for sodium oleate. The high stability in aqueous suspensions and characterization of oleate-modified MNP confirm that oleate ions are arranged as a bilayer coating at the surface of MNP. Retention of nickel was found to be highly dependent on pH, with a maximum adsorption (90%) beginning from pH = 7.5. The sorption isotherms were well fitted with the Langmuir model and the maximum nickel adsorption capacities were found to be 44 and 80 mg g-1for pH = 6.8 and 7.2, respectively. The efficient removal of nickel combined with the magnetic properties of the NMP make the oleate-modified MNP an interesting water purification tool.
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France.
authors.forename: Cécilia
authors.initials: C
authors.lastname: Magnet
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Lomenech
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France. charlotte.hurel@unice.fr.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Hurel
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France.|Laboratoire des Sciences de l'Ingénieur pour l'Environnement, Pôle Sciences et Technologie, Avenue Michel Crépeau, 17042, La Rochelle Cedex 1, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Reilhac
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France.|PIGM'Azur, Le Majestic, 4 boulevard de Cimiez, 06000, Nice, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Giulieri
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France.|PIGM'Azur, Le Majestic, 4 boulevard de Cimiez, 06000, Nice, France.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Chaze
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Persello
authors.affiliation: Université Côte d'Azur, CNRS, INPHYNI, Nice, France.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kuzhir
mesh_terms: D000327:Adsorption; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D009532:Nickel / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D019301:Oleic Acid / Q000737:chemistry*
chemical_list: D058185:Magnetite Nanoparticles; D019301:Oleic Acid; D009532:Nickel
keywords: Nickel adsorption; Sodium oleate; Superparamagnetic particles; Surface coating; Water treatment