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Öğe Antibacterial glass films prepared on metal surfaces by sol-gel method(Springer, 2010) Kiraz, Nadir; Kesmez, Omer; Burunkaya, Esin; Budama, Leyla; Acar, Burcin; Asilturk, Meltem; Camurlu, H. ErdemThis paper describes the preparation and characterization of glass films consisting of SiO2, Li2O, Na2O, K2O or MgO in varying compositions on stainless steel and aluminum substrates by sol-gel method. Silver phosphate or silver incorporated zeolite was also introduced into the sols for obtaining antibacterial effect. The SiO2/Li2O/Na2O system having the composition of 85:5:10 wt% was found as the optimum for obtaining a stable sol and film formation. The films were investigated by scanning electron microscopy (SEM) and electron dispersive analysis by X-ray (EDX), Fourier transformed infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA). Homogenous films having 300 +/- A 20 nm thicknesses were formed by spin coating and then by curing at 500 A degrees C for 1 h. Obtained films had high adherence to the metal substrates and they were also durable in acidic, basic or NaCl environments. They also presented a powerful antibacterial effect against E. coli.Öğe Effect of acid, water and alcohol ratios on sol-gel preparation of antireflective amorphous SiO2 coatings(Elsevier Science Bv, 2011) Kesmez, Omer; Burunkaya, Esin; Kiraz, Nadir; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, ErtugrulVarying amounts of nitric acid catalyst, water and ethyl alcohol were used in the preparation of SiO2 sols by hydrolysis and condensation reactions of tetraethyl orthosilicate in a one step acid catalysis process. Hydrolysis of TEOS was followed by FT-IR analyses. Size of SiO2 particles was seen to vary in 8-41 nm range with respect to changing HNO3 and water amounts in the sols. Gelation occurred in some systems. Surfaces of films were examined by FESEM and AFM, after coating on glass substrates by dip coating. Thicknesses of the films were measured to be in the range of 80-120 nm. 5.6 +/- 0.2% point increase in light transmittance was obtained when HNO3/TEOS (mol/mol) ratio of 4.74 x 10(-4) and H2O/TEOS (mol/mol) ratio of 9.08 were utilized. Sols were found to be stable for months and coatings prepared after 45 days still provided 5.2 +/- 0.2% point increase in light transmittance. (C) 2011 Elsevier B.V. All rights reserved.Öğe Effect of amine catalysts on preparation of nanometric SiO2 particles and antireflective films via sol-gel method(Springer, 2010) Kesmez, Omer; Kiraz, Nadir; Burunkaya, Esin; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, ErtugrulSiO2 sols were prepared by hydrolysis and condensation reactions of tetraethyl orthosilicate through a one step acid or a two step acid + base catalysis process, in the presence of nitric acid and four different base catalyzers, namely trimethylamine, triethylamine, tripropylamine and tributylamine. Hydrolysis of TEOS was followed by FT-IR analyses. Particle size distributions of the sols were evaluated after predetermined durations in 1-22 days. Particle growth was seen to be faster in amine catalyzed systems than in one step acid catalyzed system. The highest rate of growth was in triethylamine catalyzed system. Glass substrates were dip coated with the prepared SiO2 sols. Effect of sol aging duration on film thickness and on light transmittance properties of the films was investigated with respect to type of base catalyst. Thicknesses of the films which were measured to be in the range of 100-400 nm, were seen to increase with aging duration of the sols. Triethylamine catalyzed system presented the highest film thickness. Films obtained from one step acid catalyzed system presented an increase of 4.8%; whereas acid + base catalyzed films provided an increase in the light transmittance of 5.7% in the first 4 days of aging. Surfaces of films were examined by FESEM and AFM. The antireflective character of the films was verified by diffuse reflectance analyses.Öğe Hydrophilic hybrid SiO2:polyethylene glycol-3-isocyanato-propyltrietoxysilane nanocomposite films(Elsevier Science Sa, 2012) Burunkaya, Esin; Kesmez, Omer; Kiraz, Nadir; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, ErtugrulSiO2:polyethylene glycol (PEG)-3-isocyanato-propyltrietoxysilane (IPTES) hydrophilic films were prepared from PEG having various average molecular weights, namely 200, 400 and 600; SiO2 nanoparticles, and tetraethyl orthosilicate (TEOS) through sol-gel method. SiO2 nanoparticles were utilized in various amounts to enhance the mechanical properties and hydrophilic character of the films. Films were characterized by Fourier transformed infrared spectroscopy, field emission scanning electron microscopy, atomic force microscopy, adhesion test, humidity test and water contact angle (WCA) measurements. Thicknesses of the obtained films were about 800 nm. Incorporation of TEOS enhanced adhesion of film to substrate as well as improving stability of the film against water. WCA was seen to decrease, and porosity and surface roughness was seen to increase with increase in SiO2 nanoparticle content of the films. Increase in PEG molecular weight also resulted in a decrease in the WCA, thus WCA as low as 15 degrees was obtained. (C) 2012 Elsevier B.V. All rights reserved.Öğe Katyon veya anyon katkılanmış, nano tio2'in sentezi ve seçilmiş kirleticilerin fotokatalitik yıkımı zerine etkisinin araştırılması: Ortam Ara Ürünlerinin ve Toksik Etkilerinin Belirlenmesi(2014) Erdemoğlu, Sema; Özmen, Murat; Yesılada, Özfer; Asiltürk, Meltem; Güngördü, Abbas; Kiraz, Nadir; Özmen, Nesrin[Abstract Not Available]Öğe Katyon veya anyon katkılanmış, nano tio2'in zentezi ve seçilmiş organik kirleticilerin fotokatalitik yıkımı üzerine etkisinin araştırılması: Ortam ara ürünlerinin ve toksik etkilerinin belirlenmesi(2014) Erdemoğlu, Sema; Özmen, Nesrin; Kiraz, Nadir; Asiltürk, Meltem; Güngördü, Abbas; Özmen, Murat; Yesılada, Özfer[Abstract Not Available]Öğe N-heterocyclic carbene Pd(II) complex supported on Fe3O4@SiO2: Highly active, reusable and magnetically separable catalyst for Suzuki-Miyaura cross-coupling reactions in aqueous media(Elsevier Science Sa, 2021) Akkoc, Mitat; Bugday, Nesrin; Altin, Serdar; Kiraz, Nadir; Yasar, Sedat; Ozdemir, IsmailA new type magnetic nano Fe3O4@SiO2@NHC@Pd-MNPs heterogeneous catalyst was fabricated and characterized by Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Energy Disperse X-ray analysis (EDX), Thermogravimetric Analysis (TGA), Differential Thermal Analysis (DTA), and Scanning Electron Microscopy (SEM). The loading amount of Palladium (Pd) to magnetic nano Fe3O4@SiO2@NHC@Pd-MNPs was measured by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) analysis. The catalytic activity of magnetic nano Fe3O4@SiO2@NHC@Pd-MNPs heterogeneous catalyst was examined on Suzuki-Miyaura cross-coupling reactions of aryl halides with different substituted arylboronic acid derivatives. All coupling reactions yielded excellent results and high TOF (up to 76528 h(-1)) in the presence of 2 mg of Fe3O4@SiO2@NHC@Pd-MNPs catalyst (0.0197 mmolg(-1), 0.00394 mmol%Pd) at 80 degrees C in 2-propanol/H2O (1:2). In addition, the magnetic nano Fe3O4@SiO2@NHC@Pd-MNPs catalyst was easily recovered by using an external Nd-magnet and reused for the Suzuki cross-coupling reactions. The catalyst showed strong structural and chemical stability and was reused six times without losing its catalytic activity substantially. (C) 2021 Elsevier B.V. All rights reserved.Öğe Nano metal oksit partiküllerinin sentezi ve yüksek kırılma indisine sahip ince kaplamaların hazırlanması(2011) Sayılkan, Funda; Asiltürk, Meltem; Kiraz, Nadir; Burunkaya, Esin[Abstract Not Available]Öğe A novel approach to the hydrothermal synthesis of anatase titania nanoparticles and the photocatalytic degradation of rhodamine B(Turkish Journal of Chemistry, 2006) Akarsu, Murat; Asiltürk, Meltem; Sayılkan, Funda; Kiraz, Nadir; Arpaç, Ertuğrul; Sayılkan, HikmetAbstract: A novel approach was developed for the synthesis of high-dispersed anatase nano-TiO2 by a hydrothermal process without solvent at 200 °C in 1 h. It was characterized using XRD, TEM, BET and elemental analysis. Nanoparticle-TiO2 was used as a photocatalyst by considering complete degradation of Rhodamine B (RB) dye. The photocatalytic reaction parameters such as photocatalyst amount, irradiation time and dye concentration were optimized and it was found that 0.125 wt% catalyst in 30 mg/L of RB aqueous solution is adequate for full degradation of RB in 50 min with 770 W/m2 irradiation power. Photocatalytic activity of the nanoparticle- TiO2 was compared with Degussa P-25 at optimum catalysis conditions determined for the nanoparticle- TiO2. It was concluded that when compared to Degussa P-25, the nanoparticle- TiO2 can be repeatedly used with increasing photocatalytic activity. The results revealed that the photodegradation of RB proceeds by pseudo first-order reaction kinetics in which the rate constant of the degradation is 0.132 min?1.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, HikmetPure 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.Öğe Preparation of aluminum-doped zinc oxide (AZO) nano particles by hydrothermal synthesis(Springer, 2010) Burunkaya, Esin; Kiraz, Nadir; Kesmez, Oemer; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, ErtugrulAluminum doped zinc oxide (AZO) nanometric particles were synthesized by hydrothermal method. Aluminum nitrate hydrate, aluminum sec-butoxide and zinc nitrate hydrate were used as the starting materials, and n-propanol and 2-butanol were used as solvents. Ratio of Al2O3 in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175-225 A degrees C for 5 h. Ratios of alcohol, H2O and HCl to zinc nitrate hydrate were altered and 6 different sets of parameters were investigated. Obtained products were subjected to powder-XRD, particle size measurement, TEM examination and AAS analysis. Single phase AZO particles were obtained at alcohol to zinc nitrate ratio of 35, acid to zinc nitrate ratio of 0.2, at 225 A degrees C. Particle size was determined as 3.2 +/- A 0.4 nm from TEM examinations and as 1-2 nm from dynamic light scattering. Synthesized particles have amphiphilic character, thus they can be dispersed in both polar and non-polar media. It was seen from the UV-diffuse reflectance spectra that the AZO powder had low reflectance in the UV region and high reflectance in the visible region. The obtained powder has the potential to be utilized in the form of thin films for optical and electronic purposes.Öğe Preparation of Sn doped nanometric TiO2 powders by reflux and hydrothermal syntheses and their characterization(Springer, 2011) Kiraz, Nadir; Burunkaya, Esin; Kesmez, Omer; Camurlu, Hasan Erdem; Asilturk, Meltem; Yesil, Zerin; Arpac, ErtugrulHydrothermal and reflux synthesis methods were utilized for the preparation of 5% Sn doped TiO2 nanopowders. Obtained powders were subjected to particle size and specific surface area measurements, flame atomic absorption spectroscopy, X-ray diffraction analyses and transmission electron microscopy examination. TiO2 powder prepared by hydrothermal synthesis presented a bimodal particle size distribution with average particle sizes of about 3 and 10 nm, whereas TiO2 powder synthesized by reflux method had an average particle size of 7 nm. Specific surface areas of hydrothermal and reflux synthesized TiO2 were 130 and 115 m(2)/g, respectively. Sn doping in TiO2 was 95.8% in hydrothermal and 86.4% in reflux synthesis as measured by FAAS, respectively. Photocatalytic activities of the obtained TiO2 powders were evaluated by decomposition of malachite green solution in a solar box. Photocatalytic activity of hydrothermally synthesized TiO2 was fairly higher in visible light and slightly higher in UV light than the activity of reflux synthesized TiO2.Öğe Sol-gel synthesis of 3-(triethoxysilyl)propylsuccinicanhydride containing fluorinated silane for hydrophobic surface applications(Springer, 2010) Kiraz, Nadir; Burunkaya, Esin; Kesmez, Omer; Asilturk, Meltem; Camurlu, H. Erdem; Arpac, ErtugrulIn this paper, novel fluorinated silane compound was prepared by adding hydroxyl terminated Fluorolink D10H oligomer to 3-(triethoxysilyl)propylsuccinicanhydride. The obtained silane system was independently composed with 3-Aminopropyltrimethoxysilane, 3-Glycidyloxypropyltrimethoxysilane and 3-Glycidyloxypropyltriethoxysilane and, then the prepared coating solutions were applied to glass surface by spin-coating method. The chemical bonding between groups in system was investigated by Fourier Transform Infrared Spectroscopy analyses. The elemental composition of coatings was determined using Energy Dispersive X-ray Spectroscopy analyses. Its structure and surface properties were analyzed by scanning electron microscopy, atomic force microscopy, contact angle measurement and Ultraviolet-visible Absorption Spectroscopy. The amounts of fluorine on the coatings prepared with GF20-D10H-AMMO, GF20-D10H-GLYEO and GF20-D10H-GLYMO are 31, 32 and 34% at, respectively. Transparent coatings with smooth surface and uniform thickness were observed. The coatings had nanoscale roughness. The contact angles of coatings for water ranged from 88 to 107(o), and that of n-hexadecane ranged from 53 to 60(o).Öğe Sol-gel synthesis of IPTES and D10H consisting fluorinated silane system for hydrophobic applications(Springer, 2010) Burunkaya, Esin; Kiraz, Nadir; Kesmez, Omer; Asilturk, Meltem; Camurlu, H. Erdem; Arpac, ErtugrulIn this study, new fluorinated silane system was prepared by adding hydroxyl terminated Fluorolink D10H oligomer to 3-isocyanatopropyltrietoxysilane. The obtained silane system was independently composed with 3-Glycidyloxypropyltrimethoxysilane and 3-Glycidyloxy-propyltriethoxysilane. Then the prepared two different coating solutions were applied to glass surface by spin-coating method. The chemical bonding between groups in system was investigated by FTIR analysis. The elemental composition of coatings was determined by using EDX analysis. Their structure and surface properties were analyzed by scanning electron microscopy, atomic force microscopy, contact angle measurement and UV-vis spectrophotometer. The amounts of fluorine on the coatings prepared with IPTES-D10H-GLYEO and IPTES-D10H-GLYMO were 33 and 34 %wt, respectively. Transparent coatings with smooth surface and uniform thickness were obtained. The coatings had nanoscale roughness. The contact angles of coatings for water were range from 103A degrees to 110A degrees, and for n-hexadecane were range from 59A degrees to 62A degrees.Öğe Sol-gel thin films with anti-reflective and self-cleaning properties(Springer Int Publ Ag, 2012) Camurlu, Hasan Erdem; Kesmez, Omer; Burunkaya, Esin; Kiraz, Nadir; Yesil, Zerin; Asilturk, Meltem; Arpac, ErtugrulSelf-cleaning photocatalytic TiO2 films are beneficial since they reduce the maintenance cost and enhance the efficiency of various optical systems, especially thermal and photovoltaic solar systems. However, the presence of a TiO2 layer on glass reduces the transmission of incident light, which leads to a decrease in efficiency. This drawback can be overcome by applying a layer of anti-reflective coating beneath the TiO2 layer. Generally, the anti-reflective layer is porous silica. The presence of the anti-reflective layer compensates for the loss of light transmittance caused by the photocatalytic TiO2 top layer. This paper reviews some of the previous and the latest fundamental studies in the literature on anti-reflective, self-cleaning and multi-functional films. (C) 2012 Institute of Chemistry, Slovak Academy of SciencesÖğe Structural and optical properties of thin films prepared from surface modified ZrO2(Elsevier, 2011) Asilturk, Meltem; Burunkaya, Esin; Sayilkan, Funda; Kiraz, Nadir; Arpac, ErtugrulThis 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.
