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    Antibiotic amoxicillin removal from aqueous solution using magnetically modified graphene nanoplatelets
    (Elsevier Science Inc, 2016) Kerkez-Kuyumcu, Ozge; Bayazit, Sahika Sena; Salam, Mohamed Abdel
    The removal of antibiotic amoxicillin (AA) from aqueous solution was investigated using magnetically modified graphene nanoplatelets (M-GNPs). M-GNPs were prepared by mixing GNPs with freshly prepared magnetite nanopartilcles, and characterized using TEM, and XRD. The characterization results revealed the homogenous distribution of the magnetite nanopartilcles over the surface of transparent platelet-like graphene platlets. The M-GNPs proved to possess superior adsorption capacity compared with the pristine GNPs and the magnetite nanopartilces. The effects of different operational parameters which affect the removal process were explored; adsorbent amounts, contact time, initial pH, temperature, and the initial concentration of AA. The results showed the great affinity of the M-GNPs toward the AA and the maximum adsorption capacity was found to be 14.10 mg g(-1). The adsorption mechanism of AA by the M-GNPs involved pi-pi stacking and electrostatic interaction. The adsorption was studied kinetically and thermodynamically, and was found to mainly follow pseudo-second-order kinetic model, and was spontaneous and exothermic in nature. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
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    A comparative study for removal of different dyes over M/TiO2 (M = Cu, Ni, Co, Fe, Mn and Cr) photocatalysts under visible light irradiation
    (Elsevier Science Sa, 2015) Kerkez-Kuyumcu, Ozge; Kibar, Efgan; Dayioglu, Kubra; Gedik, Fadime; Akin, Ayse NIlgun; Ozkara-Aydinoglu, Seyma
    The purpose of this work is to design and develop a series of stable and effective TiO2 photocatalysts prepared by a modified precipitation method. In order to improve the photo response of the TiO2 to the visible region, the effect of addition of six successive transition metal elements of fourth period, namely chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) was studied. Two different types of dyes, methyl orange (MO, azo dye) and methylene blue (MB, thiazine dye group), were used to investigate the influence of structure of dyes on the photocatalytic degradation rates. The results showed that loading titania with 0.3 wt.% of different transition metal elements was found to have significant influences on the crystallographic structure, physical properties and optical absorption properties of titania based catalysts, as well as catalytic activity during dye degradation reactions. The optical reflection edge was obviously shifted to the visible light range with the transition metal additives. The band gap energies of the doped TiO2 samples were considerably narrower than that of plain TiO2. The different activity levels of the catalysts for both dyes clearly show that the photocatalytic activity of samples strongly depended on the metal dopant used. Among all the catalysts, Cu/TiO2 sample exhibited the highest photocatalytic activity under visible light for both of the dyes owing to the low band gap energy and delayed electron-hole recombination. (C) 2015 Elsevier B.V. All rights reserved.
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    Synergistic effect of Pt0 and M2+ (Cu2+, Ni2+, Co2+) on photo(electro) catalytic activity of TiO2 nanorod array thin films
    (Elsevier Science Sa, 2015) Kerkez-Kuyumcu, Ozge; Boz, Ismail
    M2+ (Cu2+, Ni2+, Co2+) and Pt-0-M2+ loaded TiO2 nanorod film samples were prepared on transparent conducting oxide glass (FTO/F:SnO2). Two step method was used consisting a hydrothermal method to grow TiO2 nanorods on the surface and an ultrasonic-assisted sequential cation adsorption method to modify the nanorods. The samples were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy. The photoelectrochemical properties of the samples were evaluated by linear sweep voltammetry, photocatalytic activities were tested by methylene blue degradation under visible light. M2+-TiO2/FTO samples were compared with Pt-0-M2+-TiO2/FTO samples; the synergistic effect of Pt-0 and M2+ was discussed. Pt-0-Ni2+-TiO2/FTO showed superior photoelectrocatalytic activity with 1.358 mA cm(-2) and 78.3% methylene blue degradation under visible light. Quantum yields were calculated separately as a sign for H-2 generation rate and as a conversion of methylene blue molecule per absorbed light. (C) 2015 Elsevier B.V. All rights reserved.