title: Arsenic sorption by nanocrystalline magnetite: an example of environmentally promising interface with geosphere.
abstract: In this paper, the sorption of arsenic onto nanocrystalline magnetite mineral Fe3O4 was studied in a model system. Nanocrystalline magnetite was produced by mechanical activation in a planetary ball mill from natural microcrystalline magnetite. As a consequence of milling, the specific surface area increased from 0.1m(2)/g to 11.9 m(2)/g and the surface site concentration enhanced from 2.2 sites/nm(2) to 8.4 sites/nm(2). These changes in surface properties of magnetite lead to the enhancement of arsenic removal from model system. The best sorption ability was achieved with magnetite sample activated for 90 min. In this case the sample was able to absorb around 4 mg/g. The structural changes of magnetite were also observed and the new hematite phase was detected after 120 min of milling. A good correlation between the decreasing particle size, increasing specific surface area and reduction of saturation magnetization was found. In desorption study, KOH and NaOH were found as the best eluents where more than 70% of arsenic was released back into the solution. The principal novelty of the paper is that mineral magnetite, truly one nature's gift can be used after "smart" milling (mechanical activation) as an effective arsenic sorbent.
authors.affiliation: Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04353 Košice, Slovakia. Electronic address: bujnakova@saske.sk.
authors.forename: Z
authors.initials: Z
authors.lastname: Bujňáková
authors.forename: P
authors.initials: P
authors.lastname: Baláž
authors.forename: A
authors.initials: A
authors.lastname: Zorkovská
authors.forename: M J
authors.initials: MJ
authors.lastname: Sayagués
authors.forename: J
authors.initials: J
authors.lastname: Kováč
authors.forename: M
authors.initials: M
authors.lastname: Timko
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000032:analysis* / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods; D005290:Ferric Compounds / Q000737:chemistry; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D007700:Kinetics; D008280:Magnetics; D046529:Microscopy, Electron, Transmission; D008903:Minerals / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D017680:Potassium Compounds / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D005290:Ferric Compounds; D006878:Hydroxides; D008903:Minerals; D017680:Potassium Compounds; C000499:ferric oxide; D012972:Sodium Hydroxide; D001151:Arsenic; C029943:potassium hydroxide; D052203:Ferrosoferric Oxide
keywords: Arsenic; Mechanical activation; Nanocrystalline magnetite; Sorption