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Öğe 157-nm Laser Micromachining of N-BK7 Glass and Replication for Microcontact Printing(Springer-Verlag, 2003) Dyer, P. E.; Maswadi, S. M.; Walton, C. D.; Ersöz, Mustafa; Fletcher, P. D. I. ; Paunov, V. N.We report etch-rate and probe-beam-deflection studies of N-BK7 glass ablated using a 157-nm F-2 laser. It is found that controllable material removal at the nanometre level is possible above an ablation threshold of 250 mJ cm(-2). Contact mask printing shows well-defined features can be micromachined in this glass with sub-micron resolution capability. Micro-features produced in this way have been replicated by polydimethylsiloxane (PDMS) moulding and the stamps used to print arrays of fluorescent molecules with sub-micron fidelity.Öğe Adsorption Characteristics of Heavy Metal İons Onto a Low Cost Biopolymeric Sorbent From Aqueous Solutions(Elsevier, 2006) Ünlü, Nuri; Ersöz, MustafaIn this study, the adsorption conditions of Cu(II), Pb(II) and Cd(II) metal ions onto sporopollenin have been studied. The different variables effecting the sorption capacity such as pH of the solution, adsorption time, initial metal ion concentration and temperature have been investigated. Adsorption isotherms correlated well with the Freundlich type adsorption isotherm and adsorption capacities were found to be 0.0195, 0.0411 and 0.0146 mmol g(-1) for Cu(II), Pb(II) and Cd(II) metal ions, respectively. Experimental data were also evaluated to find out kinetic characteristics of the adsorption process. Adsorption processes for three target heavy metal ions were found to follow pseudo-second order type adsorption kinetics. Intraparticle diffusion was found to take part in adsorption processes but it could not be accepted as the primary rate-determining step. The mean free energies of adsorption (E) were found to be between 8 and 16 kJ mol(-1) for the metal ions studied and therefore adsorption mechanism for the adsorbent was explained as an ion-exchange process. But it was observed that chelating effect is also playing an important role in the adsorption of metal ions onto sporopollenin. Thermodynamic parameters, Delta H degrees, Delta S degrees and Delta G degrees were also calculated from graphical interpretation of the experimental data. Standard heats of adsorption (Delta H degrees) were found to be endothermic and AS' values were calculated to be positive for the adsorption of Cu(II), Pb(II) and Cd(II) ions onto the adsorbent. Negative Delta G degrees values indicated that adsorption process for these three metal ions onto sporopollenin is spontaneous.Öğe Adsorption of Copper ( II ) , Cobalt ( II ) , and Iron ( III) Ions From Aqueous Solutions on Poly ( Ethyleneterephthalate ) Fibers(JOHN WILEY & SONS INC, 1998) Yigitoğlu, Mustafa; Ersöz, Mustafa; Coşkun, Ramazan; Şanlı, Oya; Ünal, Halil İbrahimThe adsorption behavior of poly ( ethylene terephthalate ) ( PET ) fibers to-wards copper ( II ) , cobalt ( II ) , and iron ( III ) ions in aqueous solutions was studied by abatch equilibriation technique. Influence of treatment time, temperature, pH of thesolution, and metal ion concentration on the adsorption were investigated. Adsorptionvalues for metal ion intake followed the following order: Co ( II )úCu(II)úFe( III ) .One hour of adsorption time was found sufficient to reach adsorption equilibrium forall the ions. The rate of adsorption was found to decrease with the increase in thetemperature. Langmuir adsorption isoterm curves were found to be significant for allthe ions studied. The heat of adsorption values were calculated as05,02.8, and03.6kcal /mol for Cu ( II ) , Co ( II ) , and Fe( III ) ions, respectively.Öğe Adsorption of Cu(II) From Aqueous Solution by Using Modified Fe3O4 Magnetic Nanoparticles(Elsevier, 2010) Özmen, Mustafa; Can, Keziban; Arslan, Gülsin; Tor, Ali; Çengeloğlu, Yunus; Ersöz, MustafaIn this study, surface modification of Fe3O4 nanoparticles (Fe3O4-NPs) was carried out with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA). The obtained modified-NPs (GA-APTES-NPs) were evaluated for Cu(II) removal from water by adsorption. First, Fe3O4-NPs were synthesized by co-precipitation of Fe2+ and Fe3+ with Fe2+/Fe3+ in a ratio of 1.75 in an ammonia solution, then surface of Fe3O4-NPs was modified with APTES and GA. The morphology and properties of the NPs were examined by Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA) and magnetization measurement. The batch experiments showed that modified-NPs can be effectively used to remove Cu(II) from water. Adsorption equilibrium was achieved in 15 min. The adsorption of Cu(II) by GA-APTES-NPs strongly depends on the pH of the solution. Maximum removal of Cu(II) was obtained at pH between 4.0 and 5.3. The isotherm analysis indicated that the sorption data can be represented by both Langmuir and Freundlich isotherm models. The regeneration studies also showed that GA-APTES-NPs could be re-used for the adsorption of Cu(II) from aqueous solutions over three cycles without change in the sorption capacity and magnetization properties.Öğe Adsorption of Cu(II) onto silica gel-immobilized Schiff base derivative(ELSEVIER, 2009) Gübbük, I. Hilal; Gup, Ramazan; Kara, Huseyin; Ersöz, Mustafa4-chloroisonitroacetophenone 4-aminobenzylhydrazone (CAAH) chemically anchored on a silica gel surface, has been used for Cu(II) sorption from aqueous solution. The surface modification processes was performed after silanization of silica, then analyzed by elemental analysis, infrared spectroscopy, and thermogravimetry. The sorption behavior of copper(II) was evaluated by the use of batch and column methods. The influences of the concentration, temperature and pH for sorption on the immobilized silica gel with Schiff base were investigated. The obtained dynamic data were fitted to Freundlich, Langmuir and Dubinin-Raduskevich (D-R) isotherms. The mean sorption energy (E) of copper sorption onto silica gel was calculated from D-R isotherm indicating a chemical ion-exchange. The thermodynamic parameters such as Gibbs free energy change, enthalpy change and entropy change were calculated from the adsorption isotherms which were used to explain the mechanism of the adsorption. (C) 2009 Published by Elsevier B.V.Öğe Amperometric Glucose Biosensor Based on Glucose Oxidase, 1,10-Phenanthroline-5,6-dione and Carbon Nanotubes(ELECTROCHEMICAL SOC INC, 2014) Zor, Erhan; Öztekin, Yasemin; Ramanaviciene, Almira; Anusevicius, Zilvinas; Bingöl, Haluk; Barkauskas, Jurgis; Ersöz, MustafaA biosensor for glucose determination was fabricated by the immobilization of glucose oxidase (GOx) on carbon nanotubes (CNTs) and/or 1,10-phenanthroline-5,6-dione (PD) modified graphite rod electrodes (GOx/PD/CNTs/GR) and its amperometric response toward glucose was investigated under aerobic and anaerobic conditions. The sensitivity of the GOx/PD/CNTs/GR electrode was found to be higher compared to that of a PD-modified GR electrode without CNTs (GOx/PD/GR), implying that CNTs play an important role in the facilitation of electron transfer between the redox active site of GOx and the electrode surface. The GOx/PD/CNTs/GR biosensor exhibited a linear dependency on substrate concentration in a range from 0.0 until 50.0 mM of glucose with oxygen present and from 0.0 until 62.5 mM of glucose in the absence of oxygen. With oxygen present, the limit of detection (LOD) values were determined to be 5.4 and 8.0 mM, and the limit of quantitation values (LOQ) were calculated as 16.2 and 24 mM for GOx/PD/GR and GOx/PD/CNTs/GR, respectively. In the absence of oxygen, the LOD values were calculated as 4.2 and 10.7 mM, and the LOQ values were calculated as 12.6 and 32.1 mM for GOx/PD/GR and GOx/PD/CNTs/GR, respectively. When examining the interference effect of uric acid for GOx/PD/GR and GOx/PD/CNTs/GR electrodes, no significant changes in the amperometric response of the modified electrodes were observed up to 100.0 mM of uric acid. (C) 2014 The Electrochemical Society. All rights reserved.Öğe Arsenic(V) removal from underground water by magnetic nanoparticles synthesized from waste red mud(ELSEVIER SCIENCE BV, 2012) Akın, İlker; Arslan, Gülsin; Tor, Ali; Ersöz, Mustafa; Cengeloğlu, YunusIn this study waste red mud (bauxite residue) sample obtained from Seydisehir (Konya, Turkey) was evaluated for the synthesis of Fe3O4 nanoparticles (NPs) in ammonia solution that can be used to remove As(V) from both synthetic and natural underground water samples. The synthesized Fe3O4-NPs were characterized by using TEM, VSM, XRD, SAXS,TGA and FT-IR spectroscopy. The Fe3O4-NPs assumed a near-sphere shape with an average size of 9 nm. The results showed that synthesized Fe3O4-NP5 from waste red mud have satisfactory magnetic properties and As(V) sorption capacity, especially at low equilibrium arsenate concentrations. (c) 2012 Elsevier B.V. All rights reserved,Öğe Assembly of Non-Aqueous Colloidal Dispersions under External Electric Field(CRC PRESS-TAYLOR & FRANCIS GROUP, 2014) Ünal, Halil İbrahim; Erol, Özlem; Ersöz, Mustafa[Abstract not Available]Öğe Binding Affinity of Serum Proteins to Epoxy Modified Magnetite Nanoparticles(2012) Maltaş, Esra; Özmen, Mustafa; Yıldız, Salih; Ersöz, MustafaSuperparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by co-precipitating Fe2+ and Fe3+ in an ammonia solution. SPIONs modified with [3-(2,3-epoxypropoxy)propyl] trimethoxy silane, which resulted in the presence of a high population of epoxy groups on the particles surface. The surface functional SPIONs can be bound with active bio-substance, and have a wide application prospect in the fields of biology and medicine. The binding percentage of proteins was studied with epoxy modified SPIONs. Several serum proteins including albumin, ?-globulin, hemoglobin, cytochrome c and myoglobin were studied for immobilization. Epoxy terminated SPIONs were shown the highest binding ability for immobilization of cytochrome c and hemoglobin with 1 and 0.86 mg total protein at a particle concentration of 20 mg/mL among proteins, respectively. This binding ability was also shown by using sodium dodecylsulfate polyacrylamide gel electrophoresis technique (SDS-PAGE). Protein attachments were also examined by Scanning Electron Microscopy (SEM). © 2012 American Scientific Publishers. All rights reserved.Öğe Calixarene assembly with enhanced photocurrents using P(SNS-NH2)/CdS nanoparticle structure modified Au electrode systems(ROYAL SOC CHEMISTRY, 2015) Sayın, Serkan; Azak, Hacer; Yıldız, Hüseyin Bekir; Çamurlu, Pınar; Akkuş, Gülderen Uysal; Toppare, Levent; Ersöz, MustafaTwo novel calix[n] arene-adorned gold electrodes producing high photocurrent intensities were successfully constructed by embedding gold electrode surfaces with both P(4-(2,5-di(thiophen-2-yl)-1H- pyrrol-1-yl)benzenamine) conducting polymer and 4-mercaptoboronic acid-functionalized semiconductor CdS nanoparticles to facilitate the binding of calix[n]arene sulfonic acids with nanoparticles. This structure enabled an electron transfer cascade that both induced effective charge separation and efficiently generated photocurrent. The prepared electrodes were used to generate photocurrent by relying on the host-guest interactions of guests Br-3(-) and I-3(-), which if positioned well in the system was able to fill electron-hole pairs of CdS nanoparticles. As a result, host calixarene derivatives crucially held Br-3(-) and I-3(-) ions at a substantial distance from CdS nanoparticles. Furthermore, the effects of various calixarenes on the photocurrent obtained indicate that the generation of photocurrent intensities by the system depends on the cavity sizes of calixarene derivatives, which provide an essential center for Br-3(-) and I-3(-) ions.Öğe Diffusion and Selective Transport of Alkali Cations on Cation-exchange Membrane(MARCEL DEKKER INC, 1995) Ersöz, MustafaThe diffusion coefficients and selective transport for alkali metal cations through a charged polysulfonated ICE-450 ion-exchange membrane were measured as a function of pH at 25 degrees C. The permeability and diffusion coefficients were found to increase in the sequence Cs+ greater than or equal to K+ > Na+ > Li+. The relationship between the permeability and the diffusion coefficients, and the hydrated radii of cations in the membrane were shown. This sequence was also explained by considering the hydration of ions in the membrane. The selectivity transport of K-Na and K-Li binary systems at various pH gradients through the membrane were also investigated under various conditions. In the selective transport of metal ions, the selectivity depended on both the hydrated ionic size and the interaction between the fixed groups in the membrane and the metal ions.Öğe The Effect of Accompanying Anion and the Competitive Transport of Ni(Ii) and Fe(Iii) Through Polysulfone Membranes(Marcel Dekker Inc, 2003) Kır, Esengül; Tor, Ali; Çengeloğlu, Yunus; Ersöz, MustafaThe effect accompanying anion on the transport of Ni2+ and competitive transport of Ni2+ and Fe3+ ions through charged polysulfone or polysulfone polyester-supported cation exchange membranes was studied under Donnan dialysis conditions. In the Donnan dialysis process, two electrolyte solutions were separated by ion permeable membrane, the one side (feed solution) initially containing metal salts or their mixtures, the other is HCl and no external potential field is applied. The transport of metal ions through membranes was correlated with the efficiency factor (EF) values as well as with fluxes and depended on the interaction between the fixed groups in the membrane and the metal ions. The EF value of Ni2+ as a single as well as mixture state was higher than that of Fe3+ for both types of membranes. The effect of accompanying anion on the transport of Ni2+ was found to be in the following order of Cl- > NO3- > SO4-2, and the results were correlated with the EF values, as well as with the membrane structure.Öğe Effect of N(4)-phenyl group on the lipophilicity scale of 2-benzoylpyridine thiosemicarbazone based on the ion transfer across the liquid/liquid interface(2006) Akgemci, Emine Güler; Bingöl, Haluk; Özçelik M.; Atalay T.; Ersöz, Mustafa[Abstract not Available]Öğe Electrochemical Characterization of Polysulfone Membranes With Different Valence Salt Solutions(Elsevier, 2006) Çimen, A.; Ersöz, Mustafa; Yıldız, S.Membrane potentials of polysulfonated cation-exchange (SA(3)S and SA(3)T) membranes for KCl, NaCl, LiCl, CaCl2 and FeCl3 solutions using Ag/AgCl electrodes were measured. The measurements were carried out for, KCl vertical bar SA(3)S or SA(3)T vertical bar MCl, (M:K, Na, Li, Cu and Fe) systems. The concentration of salt solution (KCl) was kept constant in one side of the cell, C-1, at 1x10(-2) M and was changed in the other side of the cell, C-2, from 1x10(-4) to 2 M. The alteration graphs were drawn in order to find the potential values of membranes for ln (C-1/C-2) ratio changes. Using the values, the effective fixed charge density in membrane (C-x), the average value of transport numbers (t(+/-)), and partition coefficients (K-+/-) in a polysulfonated cation-exchange membrane for different valence ions were determined. Using the Donnan equation and the Teorrel-Meyer-Sievers theory, membrane diffusion potentials and Donnan potentials were calculated both theoretically and experimentally.Öğe Electrochemical investigation of heavy metal ion transfer across the water/1,2-dichloroethane interface assisted by 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone(WILEY-V C H VERLAG GMBH, 2007) Bingöl, Haluk; Akgemci, Emine Güler; Ersöz, Mustafa; Atalay, TevfikThe transfer of heavy metal ions across the polarized water/1,2-dichloroethane (1,2-DCE) interface assisted by 9ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone (ECCAT) in the 1,2-DCE phase has been studied by cyclic voltammetry. Voltammetric waves of Pb(II) and Cd(II) ions were reversible and quasi-reversible, respectively, whereas that of Hg(II) and Zn(II) ion were irreversible. The voltammogram of Cu(II) ion showed a two-step wave, however the nature of the transfer could not be satisfactorily evaluated by analyzing the cyclic voltammetric data. When Ni(II) and Co(II) was used no peak was visible under the experimental conditions used in this study. The dependence of the half-wave potentials of Pb(II) and Cd(II) ions on the ligand concentration reveals that their ion-transfer is assisted by the formation of 1:3 metal-ECCAT complex in 1,2-DCE. The over-all association constants of [Pb(ECCAT)(3)](2+) and [Cd(ECCAT)(3)](2+) complexes in DCE-phase have been determined to be log beta(3)(0)= 14.03 and log beta(0)(3) = 15.44, respectively.Öğe The Electrochemical Properties of Polysulfone Ion-Exchange Membranes(ACADEMIC PRESS INC, 2001) Ersöz, MustafaThe ion-exchange isotherm of sodium and calcium ions and membrane potential measurements of monovalent salts (KCl and NaCl) and monovalent-divalent cation salt mixtures on the polysulfone and polysulfone with polyester support cation exchange membranes have been performed. The equilibrium cation concentration in membranes for monovalent-divalent (NaCl + CaCl2) cation salt mixtures were studied at a total concentration of 0.05 M. The electromotive force values of the cell-Ag,AgCl\MCl(a')\ membrane\MCl(a")\Ag,AgCl for monovalent salts and Ag,AgCl \MCl+CaCl2(a')\membrane\MCl +CaCl2(a")\Ag,AgCl for monovalent-divalent salt mixtures-were measured. A nonlinear regression method was used to determine effective membrane charge densities. The membrane potential of the monovalent salts for cation exchange membranes is almost linear. Membrane potential values for monovalent-divalent cation mixtures are not linear as a function of NaCl concentration and tend to be zero when the mole fraction of monovalent-divalent salts is equal. The results obtained for polysulfone-type membranes were compared with Neosepta CL-25T and CM2 cation exchange membranes.Öğe Enhanced uptake capacities and isosteric heats of CO2 and CH4 adsorption on spent coffee ground activated carbons loaded with metal ions(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2019) Kırbıyık, Çisem; Büyükbekar, Burak Zafer; Kuş, Mahmut; Ersöz, MustafaLow-cost activated carbon (AC) samples obtained from waste coffee grounds were used for CO2 and CH4 adsorption. ACs were prepared by chemical activation and carbonized at three different temperatures. AC carbonized at 800 degrees C showed a relatively high surface area (582.92 m(2) g(-1)) and high adsorption capacities of 2.6 mmol g(-1) and 1.1 mmol g(-1) at 25 degrees C for CO2 and CH4, respectively. Adsorbent samples were prepared by loading of Fe3+ metal ions onto ACs and their adsorption capacities were compared with those of nonloaded ACs. As expected, the loading of Fe3+ metal ions increased the adsorption capacities at all temperatures and the adsorption capacity of Fe3+-loaded AC carbonized at 800 degrees C was 3.1 mmol g(-1) for CO2 and 1.2 mmol g(-1) for CH4 at 25 degrees C. The isosteric heats of adsorption were calculated at 0-35 degrees C with the range of 20-35 kJ mol(-1) and 18-23 kJ mol(-1) for CO2 and CH4, respectively. According to our findings, bio-based ACs can be used as an effective and alternative adsorbent for capturing different gas molecules.Öğe Fabrication of Octyltriethoxysilane Langmuir-Blodgett Thin Film(Natl Inst Optoelectronics, 2010) Can, Keziban; Özmen, Mustafa; Gürfidan, L.; Gübbük, İlkay Hilal; Kaymak, E.; Ersöz, Mustafa; Özbek, Zikriye; Çapan, R.In the present work the monolayer properties at the air-water interface of Octyltriethoxysilane (C8TES) molecules are investigated using Langmuir isotherm graphs. Uniform and high quality Langmuir-Blodgett films of these molecules are prepared and characterized by UV-visible, atomic force microscopy and quartz crystal microbalance measurements to determine the deposition quality of these films. High transfer ratio of about 0.99 at a deposition pressure of 11 mN/m was obtained. The contact angle of water was 93.17 degrees with a surface free energy of 23.8 mN/m. The use of soluble triethoxy-based silane coupling agents under anhydrous conditions is shown to produce surfaces with a minimal number of surface defects. C8TES material has been demonstrated to produce well organised LB films and is shown to be a good candidate for application in the field of biosensors.Öğe Facilitated transfer of alkali metal ions by a tetraester derivative of thiacalix[4]arene at the liquid-liquid interface(WILEY-V C H VERLAG GMBH, 2008) Akgemci, Emine Güler; Bingöl, Haluk; Ersöz, Mustafa; Stibor, IvanThe facilitated transfer of alkali metal ions (Na+, K+, Rb+, and Cs+) by 25,26,27,28-tetraetboxycarbonylmethoxy-thiacalix[4]arene across the water/1,2-dichloroethane interface was investigated by cyclic voltammetry. The dependence of the half-wave transfer potential on the metal and ligand concentrations was used to formulate the stoichiometric ratio and to evaluate the association constants of the complexes formed between ionophore and metal ions. While the facilitated transfer of Li+ ion was not observed across the water/1,2-dichloroethane interface, the facilitated transfers were observed by formation of 1: 1 (metal: ionophore) complex for Na+, K+, and Rb+ ions except for Cs+ ion. In the case of Cs+ a 1:2 (metal: ionophore) complex was obtained from its special electrochemical response to the variation of ligand concentrations in the organic phase. The logarithms of the complex association constants, for facilitated transfer of Na+, K+, Rb+, and Cs+, were estimated as 6.52, 7.75, 7.91 (log beta(1)degrees), and 8.36 (log V), respectively.Öğe Glycine Transport Through a Charged Polysulfone Cation Exchange Membrane(Scientific Technical Research Council Turkey, 2002) Ünlü, Nuri; Kara, Hüseyin; Ersöz, MustafaThe transport of glycine through a charged polysulfone cation exchange membrane was studied as a function of pH at different initial conditions of less than pH 5.9 and the glycine permeability was explained under the experimental conditions as pH dependent interfacial transport. The glycine permeability increases with a decreasing pH in the receiver phase. The largest permeability was obtained if the initial pH oil the source side was pH 5.9 and that oil the opposite side was pH 2.0. The transport phenomena can be explained by the interfacial transport based on the interfacial chemical reaction (protonation, deprotonation or ion-exchange) between both phases in terms of the initial pH of the solution.
