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Öğe Copper sorption efficiency of p-tetranitrocalix[4]arene based high performance liquid chromatographic column(Desalination Publ, 2016) Durmaz, Fatih; Memon, Fakhar N.; Memon, Shahabuddin; Memon, Ayaz A.; Memon, Naeem A.; Kara, HuseyinPresent study deals with the sorption characteristics of p-tetranitrocalix[4]arene (3) appended silica-based high-performance liquid chromatographic (HPLC) column utilized for preconcentration, determination, and purification of Cu2+ from water. The sorption characteristics of the HPLC column were investigated for Cu2+ in column agreement. The experiments were performed in five steps that were monitored using UV-visible diode-array detector. However, all the HPLC experimental results were reconfirmed by using atomic absorption spectrophotometer. The effect of concentration on the sorption efficiency of the column was evaluated for Cu2+ and data obtained was investigated using Langmuir and Freundlich sorption isotherms. The value of coefficient of determination (R-2), i.e. 0.99, suggested that the Freundlich sorption isotherm was found to be the best fit model for Cu2+. The developed method was validated for system efficiency, accuracy, and precision, while the data obtained revealed that the developed column could be applied for the sorption of Cu2+ with adequate efficiency and repeatability.Öğe Determination of free radical on polycrystal of 4,4?-bis(chloroacetyl)diphenylether: An ESR study(Elsevier Science Bv, 2013) Ceylan, Yusuf; Usta, Ayhan; Usta, Keziban; Durmaz, Fatih; Coskun, Ahmet4,4'-Bis(chloroacetyl)diphenylether was synthesized and its polycrystal form was produced. This polycrystal sample was irradiated by gamma rays (Co-60) for 72 h. The ESR method was used to observe formation of free radical on the sample. ESR signal was not recorded from the non-irradiated sample, but the irradiated polycrystal sample exhibited complex ESR spectra. The measurements were carried out in the temperature range of 120-450 K. It was observed that the shape of the spectrum was dependent on the temperature. Two identical radicals were determined on the irradiated sample. Respectively, the spin density, hyperfine, and g values were found to be rho(Ha) = 0.53, rho(Hb) = 0.23, a(Cl) = 1.263 mT, a(Ha) = 1.486 mT, a(Hb) = 0.637 mT, and g(1) = 2.0115 for the Radical rho(Hx) = 0.22, rho(Hy) = 0.14, a(Cl) = 0.905 mT, a(Hx) = 0.615 mT, a(Hy) = 0.391 mT, and g(2) = 2.0383 for the Radical II. (C) 2013 Elsevier B.V. All rights reserved.Öğe Effect of an ITIC non-fullerene interlayer on electrical properties and external quantum efficiency of Al/ZnO/p-Si Schottky photodiodes(Springer, 2023) Oeztuerk, Teoman; Hussaini, Ali Akbar; Erdal, Mehmet Okan; Durmaz, Fatih; Yildirim, MuratMetal-semiconductor (MS) heterojunctions are one of the main components of today's technology. In the production of metal-semiconductor heterojunctions; metal oxides, insulators or polymers are inserted as interlayers between metal and semiconductor to ameliorate the durability, stability and efficiency of heterojunctions. By improving their durability, stability and efficiency through the use of ITIC as an interlayer material, the performance of these devices can be enhanced. By adding ITIC to the ZnO interlayer, ITIC: ZnO layer heterojunctions applications were carried out in this study. ITIC, a nonfullerene material, is employed as an electron acceptor material in organic solar cells. The ITIC:ZnO composite layer in our study was grown on Si substrates using spin coating method. Subsequently, Al/ZnO/p-Si and Al/ITIC:ZnO/p-Si heterojunctions were produced by physical vapor deposition method and the electrical properties of the produced devices were characterized. In these characterizations, current-voltage measurements were performed in the dark and under various light power illumination intensities ranging from 20 to 100 mW/cm(2). From the current-voltage characteristics, various electrical parameters were calculated. While the ideality factor values for Al/ZnO/p-Si were found to be 7.55 and 7.73, it was found as 6.83 and 6.65 for ITIC-doped photodiode using thermionic emission and Cheung models, respectively. The barrier height values for Al/ZnO/p-Si were 0.62 eV, 0.64 eV and 0.64 eV, while the same values were found as 0.60 eV, 0.63 eV and 0.61 eV for Al/ITIC:ZnO/p-Si using the thermionic emission, Cheung and Norde models, respectively. From current transient measurements, photosensitivity, specific detectivity and responsivity were calculated as optoelectronic parameters. Moreover, the heterojunctions demonstrated high external quantum efficiency with the addition of ITIC. According to the results, ITIC component is functional for photodiode and photodetector applications.Öğe Preconcentration and Determination of Toxic Metals by A New Calix[4]arene Bonded HPLC Column(Springer Heidelberg, 2013) Durmaz, Fatih; Memon, Fakhar N.; Memon, Naeem A.; Memon, Sibghatullah; Memon, Shahabuddin; Kara, HuseyinThe present study deals with the preconcentration and determination of toxic metal ions using p-tetranitrocalix[4]arene (3) appended silica-based new HPLC column. The synthesized material was characterized using Fourier transform infrared and scanning electron microscopy techniques. The sorption characteristics of the HPLC column were investigated for three toxic metals (Cd2+, Hg2+ and Pb2+) in column agreement. The experiments were performed in five steps that were monitored using a UV-visible diode-array detector. However, all the HPLC experimental results were reconfirmed by using atomic absorption spectrophotometer. The effect of concentration on the sorption efficiency of the column was evaluated for all the three metals and the data obtained were investigated using Langmuir, Freundlich and Dubinin-Redushkevich (D-R) sorption isotherms. The value of coefficient of determination (R (2)), i.e. 0.99, suggested that the Freundlich sorption isotherm was found to be the best-fit model for all the three toxic metal ions, whereas, mean free energy was calculated from the D-R isotherm as 5.3, 5.7, and 5.8 kJ/mol for Pb2+, Cd2+, and Hg2+, respectively; suggesting that physical electrostatic force is involved in the sorption process. The developed method was validated for system efficiency, accuracy, and precision.Öğe Simultaneous determination of some basic dyes using p-tetranitrocalix[4]arene-appended silica-based HPLC column(Royal Soc Chemistry, 2014) Memon, Shahabuddin; Memon, Fakhar N.; Durmaz, Fatih; Memon, Naeem A.; Memon, Ayaz A.; Kara, HuseyinThis study focuses on the synthesis, characterization and application of p-tetranitrocalix[4]arene-appended silica-based material as a stationary phase in high-performance liquid chromatography for the simultaneous separation of some basic dyes such as methyl violet, methyl green and methylene blue. The effect of the pH of mobile phase on the retention, separation and selectivity of these compounds was investigated. The method was validated for system efficiency, linearity, accuracy, precision, limit of detection and quantification. The limits of detection were 0.1, 0.5 and 0.3 mg L-1; whereas, the limits of quantification were observed to be 1, 1.2 and 0.9 mg L-1 for methyl violet, methyl green and methylene blue, respectively. The separation efficiency of the p-tetranitrocalix[4]arene-appended silica-based column was also compared to that of the octadecylsilane column.
