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    Chitosan grafted SiO2-Fe3O4 nanoparticles for removal of antibiotics from water
    (Springer Heidelberg, 2018) Danalioglu, Selen Tugba; Kuyumcu, Ozge Kerkez; Salam, Mohamed Abdel; Bayazit, Sahika Sena
    The antibiotic wastes in environment are very dangerous for human being because of the spread of epidemics due to increasing of the antibiotic-resistant bacteria. For reducing the proliferation of these bacteria, an environmental-friendly, cheap and non-toxic adsorbent, chitosan-grafted SiO2/Fe3O4, was developed in this study. The chitosan-grafted SiO2/Fe3O4 (Chi-SiO2/Fe3O4) nanoparticles were prepared and characterised by different physical and chemical techniques such as X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), N-2 adsorption-desorption isotherms (BET), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and zeta-potential analysis. The prepared nanoparticles were used for ciprofloxacin (CPX) adsorption from water. The nonlinear Langmuir and Freundlich isotherms were applied to experimental data. And Langmuir isotherm showed the best fit. The nonlinear pseudo-first-order and pseudo-second-order kinetic models and Weber-Morris intraparticle diffusion model were applied to kinetic data. The adsorption process followed the pseudo-second-order kinetic model. And the rate-limiting step was intraparticle diffusion step. The most suitable eluent for CPX desorption was determined as phosphate buffer solution rather than ethanol, and NaCl solution. It desorbed the 100% of CPX solution in 5h.
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    Efficient removal of antibiotics by a novel magnetic adsorbent: Magnetic activated carbon/chitosan (MACC) nanocomposite
    (Elsevier, 2017) Danahoglu, Selen Tugba; Bayazit, Sahika Sena; Kuyumcu, Ozge Kerkez; Salam, Mohamed Abdel
    A novel adsorbent, Fe3O4/activated carbon/chitosan (MACC: Magnetic activated carbon/chitosan) was prepared by a simple coprecipitation method. MACC was characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and surface area analysis. MACC adsorption ability was tested for three commonly used hazardous antibiotics: ciprofloxacin, erythromycin, and amoxicillin. Langmuir isotherm model and pseudo second order kinetic model were best fitted with experimental results. Superior uptake values were found with using MACC; 90.10, 178.57 and 52631 mg/g were calculated as the theoretical adsorption capacity (g,n) using Langmuir isotherm for ciprofloxacin, erythromycin, and amoxicillin, respectively. Finally, MACC is considered as a promising magnetically separable efficient adsorbent for antibiotics removal. (C) 2017 Elsevier B.V. All rights reserved.
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    Enhanced photoelectrochemical activity of magnetically modified TiO2 prepared by a simple ex-situ route
    (Springer, 2022) Yilmaz, Seda; Kuyumcu, Ozge Kerkez; Bayazit, Sahika Sena; Ayaz, Rana Muhammad Zunain; Akyuz, Duygu; Koca, Atif
    Modified TiO2 nanocomposites have been recognized as attractive photocatalytic materials in solar energy conversion. The aim of this study is to enhance the photoelectrochemical performance under visible light region by magnetically modified TiO2 nanocomposites (Fe3O4/TiO2 and NiFe2O4/TiO2) prepared by a simple ex-situ non-thermal route. The magnetic TiO2 nanocomposites were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), vibrational scanning magnetometry (VSM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Photoelectrochemical analysis was performed; chronoamperometry and Mott-Schottky curves were obtained. Results indicated that these non-noble, low-cost photocatalysts have shown the desired features; NiFe2O4/TiO2 have a suitable band gap to harvest visible range of solar light; they have reduced electron-hole recombination; and it is magnetically separable from reaction media. The most promising nanocomposite was found as NiFe2O4/TiO2 with a maximum photocurrent density 132 mu A cm(-2). The possible mechanism accounting for the improved photoelectrochemical performance of NiFe2O4/TiO2 is proposed.
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    Preparation of magnetic MIL-101 (Cr) for efficient removal of ciprofloxacin
    (Springer Heidelberg, 2017) Bayazit, Sahika Sena; Danalioglu, Selen Tugba; Salam, Mohamed Abdel; Kuyumcu, Ozge Kerkez
    Metal organic frameworks are widely used as adsorbent materials in recent years. In this study, the most prepared metal organic framework MIL-101 was prepared by hydrothermal method and featured magnetic property using co-precipitation method Fe3O4. Then, the prepared composite (MIL-101/Fe3O4) was first characterized using XRD, FTIR, SEM-EDS, and surface area analysis, then was used for the adsorptive removal of the most used antibiotic, ciprofloxacin (CIP). The effect of different adsorption variables which may affect the removal of CIP by MIL-101/Fe3O4 was investigated, as well as their adsorbent quantity, initial CIP concentration, pH, temperature, and contact time. The non-linear Langmuir and Freundlich isotherm were applied to experimental data. It was observed that rising solution temperature decreases adsorption efficiency, as the maximum adsorption uptake value was 63.28 mg g(-1) at 298 K and 22.93 mg g(-1) at 313 K, indicating the exothermic nature of the adsorption. The adsorption was studied kinetically and found to follow the pseudo-second-order kinetic model. The desorption of CIP from the MIL-101/Fe3O4 was investigated using three different eluents, and the results showed that phosphate-buffered solution was the most effective desorption eluent.