Yazar "Sayilkan, Funda" seçeneğine göre listele

Listeleniyor 1 - 7 / 7
  • Küçük Resim Yok
    Öğe
    Characterization and photocatalytic properties of TiO2/chitosan nanocomposites synthesized by hydrothermal process
    (Tubitak Scientific & Technological Research Council Turkey, 2016) Sayilkan, Funda; Emre, Fatma Bilge
    Nanocomposites of TiO2/chitosan (nTC) were synthesized by hydrothermal process at 200 degrees C. Photo-catalytic activity of the nanocomposites was studied with degradation of malachite green (MG) in aqueous medium. Structural and physico-chemical properties of the obtained nanocomposites were characterized by XRD, SEM, BET, FTIR, and particle size analyzer. Complete photodegradation of MG was successfully achieved with the aid of the nanocomposites. The optimum photocatalytic degradation conditions, irradiation time, irradiation power, and amount of catalyst were studied. Photocatalytic activity of the synthesized nanocomposites in terms of degradation of MG was compared with that of undoped TiO2 (synthesized by our team) and chitosan under normal conditions. It was concluded that the synthesized nanocomposites had better photocatalytic activity. The best result (100% degradation) was obtained with amount of nTC of 0.25 g and irradiation time of 120 min.
  • Küçük Resim Yok
    Öğe
    Effect of Fe3+ ion doping to TiO2 on the photocatalytic degradation of Malachite Green dye under UV and vis-irradiation
    (Elsevier Science Sa, 2009) Asilturk, Meltem; Sayilkan, Funda; Arpac, Ertugrul
    Fe3+ ion-doped TiO2 particles were synthesized by the hydrothermal process at 225 degrees C. Titanium isopropoxide (Ti(OPri)(4)) was used as precursor material. Both undoped and doped TiO2 particles were used to coat glass surface. The coated surface was examined with respect to their photocatalytic performance for degradation of Malachite Green (MG) dye in aqueous solution under UV and vis-light irradiation. The particles and the films were characterized by XRD, SEM and UV/vis/NIR techniques. The results showed that crystallite size of the hydrothermally synthesized TiO2 particles are in nanoscale. Anatase was only the crystalline phase. Doping of Fe3+ ion improved the photodegradation performance of TiO2 coated surfaces. Degradation performance of Fe3+ doped TiO2. coated surfaces determined under UV- and vis-irradiation conditions was higher than the undoped TiO2 coated surface. It was concluded that the photodegradation of 2.5 mg L-1 MG under UV-light irradiation with the catalysis of Fe3+-doped TiO2 follows the pseudo-first-order reaction kinetics with the rate constant of 0.0202 min(-1). (C) 2008 Elsevier B.V. All rights reserved
  • Küçük Resim Yok
    Öğe
    Effect of nanosized TiO2 particles on the development of Xenopus laevis embryos
    (TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY,, 2014) Birhanli, Ayse; Emre, Fatma Bilge; Sayilkan, Funda; Gungordu, Abbas
    This paper reports the toxic properties of nano-TiO2 on 2 different early life stages of Xenopus laevis. Synthesis of nano-TiO2 particles was carried out by the hydrothermal method. Characterization of nanoparticles was performed using spectral techniques including X-ray diffraction, scanning electron microscopy, and a particle-size analyzer. Embryos at the 8th stage and tadpoles at the 46th stage were exposed to 7 concentrations of nano-TiO2 in the range of 5 to 320 ppm. After 96 h of exposure, the mortality percentage of each exposure concentration was calculated and the activity of enzyme biomarkers acetylcholinesterase, carboxylesterase, glutathione S-transferase, glutathione reductase, lactate dehydrogenase, and aspartate aminotransferase were determined in living embryos and tadpoles. None of the tested concentrations of TiO2 caused statistically significant mortality or malformation (only for the embryo test) as compared to the control groups. Furthermore, we did not observe any significant changes in enzyme activities in tadpole samples from the 46th stage, although some minor changes not related to the concentrations were observed in embryos.
  • Küçük Resim Yok
    Öğe
    Hydrothermal synthesis and characterization of nanocrystalline ZrO2 and surface modification with 2-acetoacetoxyethyl methacrylate
    (Springer, 2009) Sayilkan, Funda; Asilturk, Meltem; Burunkaya, Esin; Arpac, Ertugrul
    For the utilization as inorganic/organic hybrid nanomaterials for optical purposes, nanocrytalline tetragonal ZrO2 was synthesized by hydrothermal method using zirconium(IV)-n-propoxide as precursor material. Surface of the ZrO2 particles was then modified with 2-acetoacetoxyethyl methacrylate used as a copolymer for coatings. X-ray diffraction analysis revealed that both ZrO2 and modified ZrO2 are in tetragonal crystalline phase. As proved by transmission electron microscope and particle size analysis, average particle sizes of ZrO2 and modified ZrO2 were found as 6.22 and 14.7 nm, respectively. ZrO2 powder was easily dispersed either in water or n-hexane. Ultraviolet diffuse reflectance spectrophotometer analysis for ZrO2 and surface modified ZrO2 showed that maximum absorption peaks are at 215 and 225 nm, respectively.
  • Küçük Resim Yok
    Öğe
    Photocatalytic antibacterial performance of Sn4+-doped TiO2 thin films on glass substrate
    (Elsevier, 2009) Sayilkan, Funda; Asilturk, Meltem; Kiraz, Nadir; Burunkaya, Esin; Arpac, Ertugrul; Sayilkan, Hikmet
    Pure anatase, nanosized and Sn4+ ion doped titanium dioxide (TiO2) particulates (TiO2-Sn4+) were synthesized by hydrothermal process. TiO2-Sn4+ was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn4+ doping to TiO2 against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO2-Sn4+ in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO2-Sn4+ is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO2-Sn4+ from 10 to 50% in the coating solution increased antibacterial effect. (C) 2008 Elsevier B.V. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Photocatalytic degradation of Congo Red by hydrothermally synthesized nanocrystalline TiO2 and identification of degradation products by LC-MS
    (Elsevier, 2008) Erdemoglu, Sema; Aksu, Songuel Karaaslan; Sayilkan, Funda; Izgi, Belgin; Asilturk, Meltem; Sayilkan, Hikmet; Frimmel, Fritz
    Degradation of Congo Red (CR) dye in aqueous solutions was investigated by means of photocatalysis of TiO2 which was hydrothermally synthesized at 200 degrees C in 2 h, in anatase phase with 8 nm crystallite size. Efficiency of TiO2 in photocatalytic degradation under visible irradiation was studied by investigating the effects of amount of TiO2, irradiation time, initial CR concentration and pH. It was found that complete decolorization is achieved within 30 min of irradiation. Effects of nitrate and sulphate ions and humic acid on the degradation were also tested. The results were compared with Degussa P-25 TiO2 at the same degradation conditions. Degradation products were detected using LC-MS technique. The probable pathways for the formation of degradation products were proposed. (C) 2008 Published by Elsevier B.V.
  • Küçük Resim Yok
    Öğe
    Structural and optical properties of thin films prepared from surface modified ZrO2
    (Elsevier, 2011) Asilturk, Meltem; Burunkaya, Esin; Sayilkan, Funda; Kiraz, Nadir; Arpac, Ertugrul
    This paper describes the preparation and characterization of ZrO2 thin films deposited on silicon wafer by spin coating method. Nanocrystalline ZrO2 was synthesized by hydrothermal method using zirconium (IV)-n-propoxide as a precursor material. Surface of the ZrO2 particles was then modified with 2-acetoacetoxyethyl methacrylate used as a copolymer for coatings. The optical properties, nanostructure and surface morphology of the thin films prepared from surface modified ZrO2 nanoparticles were examined by optical spectroscopy, X-ray diffraction and scanning electron microscopy, respectively. It was found that the films deposited on silicon wafer have crystalline structure of monoclinic (111) at temperature of 150 degrees C. It was observed that films depict very dense material that does not present any granular or columnar structure. It was found that optical transparency of thin ZrO2 films distributed in the range of 30-40 percent in the spectral range 400-800 nm. Refractive index of ZrO2 films were determined as functions of ZrO2 content and it was found that the refractive index increases from 1.547 to 1.643 with increased ZrO2 content. (C) 2010 Elsevier B.V. All rights reserved.