Browsing by Author "Şabikoğlu I."

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    The effect of neodymium substitution on the structural and magnetic properties of nickel ferrite
    (Elsevier B.V., 2015) Şabikoğlu I.; Parali L.; Malina O.; Novak P.; Kaslik J.; Tucek J.; Pechousek J.; Navarik J.; Schneeweiss O.
    Nickel ferrite NiFe2O4 is a typical soft magnetic ferrite with high electrical resistivity used as high frequency magnetic material. Neodymium (Nd3+) doped NiFe2O4 materials were fabricated using solid state reaction. The properties of the obtained material were investigated by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier-Transform Infrared Spectroscopy (FT-IR), magnetic measurements on SQUID and Mössbauer spectroscopy. It was found that the material consists of two different phases: Nd3+ doped NiFe2O4 and NdFeO3. The Nd3+ ions occupy cation sites of the NiFe2O4 inverse spinel structure. NdFeO3 phase occurred when the level of Nd3+ atoms exceed a percolation limit. The presence of both phases was confirmed by SEM observations. The Mössbauer spectra analysis showed two sextets, which can be ascribed to iron atoms in tetrahedral and octahedral positions. From their intensities it is concluded that Nd3+ occupies octahedral sites in the spinel structure of NiFe2O4, which were originally occupied by Ni2+. © 2015 The Authors.
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    Modeling of thorium (IV) ions adsorption onto a novel adsorbent material silicon dioxide nano-balls using response surface methodology
    (Elsevier Ltd, 2016) Kaynar Ü.H.; Şabikoğlu I.; Kaynar S.Ç.; Eral M.
    The silicon dioxide nano-balls (nano-SiO2) were prepared for the adsorption of thorium (IV) ions from aqueous solution. The synthesized silicon dioxide nano-balls were characterized by Scanning Electron Microscopy/Energy Dispersive X-ray, X-ray Diffraction, Fourier Transform Infrared and BET surface area measurement spectroscopy. The effects of pH, concentration, temperature and the solid–liquid ratio on the adsorption of thorium by nano-balls were optimized using central composite design of response surface methodology. The interaction between four variables was studied and modelled. Furthermore, the statistical analysis of the results was done. Analysis of variance revealed that all of the single effects found statistically significant on the sorption of Th(IV). Probability F-values (F=4.64–14) and correlation coefficients (R2=0.99 for Th(IV)) indicate that model fit the experimental data well. The ability of this material to remove Th(IV) from aqueous solution was characterized by Langmuir, Freunlinch and Temkin adsorption isotherms. The adsorption capacity of thorium (IV) achieved 188.2 mg g−1. Thermodynamic parameters were determined and discussed. The batch adsorption condition with respect to interfering ions was tested. The results indicated that silicon dioxide nano-balls were suitable as sorbent material for adsorption and recovery of Th(IV) ions from aqueous solutions. © 2016 Elsevier Ltd