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Synthesis and characterization of ultrasound assisted "graphene oxide-magnetite" hybrid, and investigation of its adsorption properties for Sr(II) and Co(II) ions

Tayyebi, A ; Sharif University of Technology | 2015

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  1. Type of Document: Article
  2. DOI: 10.1016/j.apsusc.2015.06.087
  3. Publisher: Elsevier , 2015
  4. Abstract:
  5. Magnetite nanoparticles with a size distribution of 15-21 nm were synthesized and decorated onto surface of graphene oxide by ultrasound assisted precipitation. Size and size distribution of the obtained M-GO hybrid were appreciably finer than the hybrids prepared by stirring method. M-GO is a superparamagnetic material with saturation magnetization of 31 emu g-1. The Langevin equation was successfully applied for estimation of size of Fe3O4 nanoparticles in M-GO hybrid, with maximum error of 17.5%. The study put forward a formation mechanism for M-GO, based on instrumental analyses. Adsorption isotherms of Sr2+ and Co2+ ions, which were fitted by Langmuir monolayer model, displayed two-fold higher capacity for Co2+ ions, presumably due to its similarity to Fe2+ (of Fe3O4 component). Uptake of both Co2+ and Sr2+ ions were endothermic, and spontaneous, however the former proceeded through inner-shell complex formation, while the latter took place via ion exchange mechanism. Rate of adsorption of Co2+ was faster, but for both ions, chemical reaction was the rate determining step. Sorption of Sr2+ and Co2+ ions greatly increased at pHs above 5, where (1) surface zeta potential changed its sign, and (2) deprotonating reactions at the surface became complete
  6. Keywords:
  7. Graphene oxide ; Inner-shell complex ; Adsorption ; Adsorption isotherms ; Differential equations ; Graphene ; Ion exchange ; Ions ; Iron compounds ; Magnetite ; Magnetite nanoparticles ; Nanoparticles ; Precipitation (chemical) ; Saturation magnetization ; Size distribution ; Surface reactions ; Synthesis (chemical) ; Ultrasonics ; Formation mechanism ; Graphene oxides ; Inner shell ; Ion exchange mechanisms ; Langevin equation ; Size and size distributions ; Superparamagnetic materials ; Synthesis and characterizations ; Cobalt compounds
  8. Source: Applied Surface Science ; Volume 353 , 2015 , Pages 350-362 ; 01694332 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0169433215014312