Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki

Article | 2017 | Electroanalysis29 ( 10 ) , pp.2377 - 2384

Newly synthesized poly(styrene-g-oleic amide) was coated onto a rhodium nanoparticle modified glassy carbon (GC) surface for the fabrication of horseradish peroxidase based biosensor used for hydrogen peroxide detection. The rhodium modifed electrode presented ten times higher signal than unmodified electrode even at low elecrtroactive enzyme quantity by enhancing the electron transfer rate at the applied potential of -0.65 V. The biosensor designed by under the optimized rhodium electrodeposition time exhibited a fast response less than 5 s, an excellent operational stability with a relative standard deviation of 0.6 % (n=6), an ac . . .curacy of 96 % and a large linear range between 50 µM and 120 mM for hydrogen peroxide. Detection limit and the sensitivity parameters were calculated to be 44 µM and 57 µA mM-1 cm-2, respectively by preserving its entire initial response up to the 15 days, while only 20 % of its initial response was lost at the end of one month. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei Daha fazlası Daha az

Korkut, Şeyda | Kılıç, Muhammet Samet | Uzunçar, Sinan | Hazer, Baki

Article | 2016 | Analytical Letters49 ( 14 ) , pp.2322 - 2336

A carboxylated poly(styrene-b-isoprene-b-styrene) triblock copolymer was synthesized for the construction of an enzymatic fuel cell. Glucose oxidase and bilirubin oxidase were chemically immobilized via the carboxylated functional groups of the polymer. The enzymatic fuel cell working electrodes were modified with graphene to accelerate the electron transfer rate of the system. Essential design and operational parameters were carefully optimized for improving the power of the enzymatic fuel cell. A power density of 20 µW cm-2 with only 4 µg of immobilized bilirubin oxidase was generated from 30 mM glucose at 0.72 V. The improved enz . . .ymatic fuel cell was tested in a plant leaf. A power density of 14 nW cm-2 was generated with glucose produced by photosynthesis reactions conducted during 30 min in the leaf. © 2016, Taylor & Francis Group, LLC Daha fazlası Daha az

Kahraman, Bekir Fatih | Altın, Ahmet | Altın, Süreyya | Demirel-Bayık, Gülçin

Article | 2017 | Soil and Sediment Contamination26 ( 5 ) , pp.486 - 500

Nutrient enhancement of bioremediation with nitrogen, namely biostimulation, increases process performance. Selection of a proper nitrogen source is critical for bioremediation applications. In this study, the effects of different nitrogen sources on biodegradation of C10–C25 n-alkane compounds in diesel fuel-spiked soil were revealed, and the most appropriate nitrogen source for biodegradation of semi- and non-volatile n-alkanes was investigated. Bioremediation of diesel fuel contaminated soil was monitored in lab-scale reactors for 15 days. Ammonium sulfate, potassium nitrate and urea were used as nitrogen sources. Carbon dioxide . . .and oxygen levels in the reactors were recorded to monitor microbiological activity. Contaminant removal process was investigated by pH, heterotrophic plate count, total petroleum hydrocarbons (TPH) and C10–C25 n-alkane analyses. First-order kinetic constants were calculated via respirometric and contaminant concentration data. According to total C10–C25 n-alkane removal levels and degradation rate constants, ammonium sulfate addition resulted in the most efficient contaminant removal followed by potassium nitrate and urea. Simultaneous degradation of individual n-alkanes was observed for all of the nitrogen sources. Urea addition changed the distribution of individual n-alkane concentrations relative to the pre-experimental concentrations. Nitrogen source type had no differential effect on degradation rates of semi- (C10–C16) and non-volatile (C17–C25) fractions. © 2017 Taylor & Francis Group, LLC Daha fazlası Daha az

Korkut, Şeyda | Uzunçar, Sinan | Kılıç, Muhammet Samet | Hazer, Baki

Article | 2016 | Instrumentation Science and Technology44 ( 6 ) , pp.614 - 628

A novel continuous flow biosensor based on gold nanoparticles and poly(propylene-co-imidazole) was developed for the online determination of p-benzoquinone. The amperometric response was measured as a function of p-benzoquinone concentration at an applied potential of -50 mV. The hydrogen peroxide concentration was optimized and fixed at 1 mM in samples. The mass transfer resistance of the copolymer film was minimized, and the flow cell was regenerated quickly at 1 mL/min. The resulting device provided good analytical performance based on a linear dynamic range from 5–100 µM, a short response time of 3 s, a detection limit of 3.3 µM . . ., excellent repeatability with a relative standard deviation of 0.82%, long-term stability of 95% after four weeks, and an accuracy of 105%. The gold nanoparticles enhanced the electron transfer rate on the electrode. The apparent Michaelis-Menten constant was 4 mM, showing that the enzyme retained catalytic specificity and provided high activity for p-benzoquinone. © 2016, Taylor & Francis Daha fazlası Daha az

Korkut, Şeyda | Uzunçar, Sinan | Kılıç, Muhammet Samet | Hazer, Baki

Article | 2019 | Instrumentation Science and Technology47 ( 1 ) , pp.1 - 18

A new amperometric urea biosensor based on gold nanoparticle embedded poly(propylene-co-imidazole) was developed for the determination of urea. The urease adsorbed on the polymeric film catalyzed the hydrolysis of urea to ammonium and bicarbonate ions and the ammonium was then electrooxidized on the gold electrode with the aid of gold nanoparticles at +0.2 V versus Ag/AgCl using differential pulse voltammetry. The biosensor provided a linear current response to urea concentration from 0.1 to 30 mM, a detection limit of 36 µM, a relative standard deviation of 2.43% (n = 18), and excellent storage stability, as the current decrease wa . . .s only 3% after 75 days. The operation of the biosensor was evaluated by the analysis of municipal sewage wastewater collected from the inlet pipe of the treatment plant of Zonguldak City in Turkey. The effects of possible interferants were also characterized. © 2018, © 2018 Taylor & Francis Daha fazlası Daha az

Türer, Dilek | Genç, Ayten

Article | 2005 | JOURNAL OF HAZARDOUS MATERIALS119 ( 01.Mar ) , pp.167 - 174

The electroremediation experiments were conducted on artificially polluted soils by introducing a single metallic contaminant (Pb, Zn and Cu) and multiple metallic contaminants (Pb + Zn + Cu). Based on sequential extraction results, it was observed that the removal efficiencies of lead, zinc and copper vary depending on types of contamination. When the soil was contaminated only by lead, the removal efficiency was found to be 48%. However, the removal efficiency of lead decreased to 32% when the soil was contaminated by the combination of lead, zinc and copper. Similar results were observed for zinc and copper. The corresponding rem . . .oval efficiency values for zinc and copper were 92% and 37%, and 34% and 31%, respectively. Effects of electrode geometry on the removal efficiency of metals were investigated by constructing a multiple anode arrangement. In this arrangement, the electrokinetic unit consists of three cylinders, which lie one inside the other, and the soil was placed in the middle cylinder. The central cylinder was the cathode well and the outer cylinder was the anode well, where eight identical anode electrodes were placed in octagonal with respect to the cathode electrode. By using this electrode arrangement in removal of metals from the soil contaminated with the combination of three metals (Pb + Zn + Cu), the removal efficiencies of lead, zinc and copper were found to be 29%, 18% and 18%, respectively. As it can be seen, these numerical values are much lower than the values that were obtained when the traditional two-plate electrode arrangement used in the electroremediation experiments (32%, 37% and 31%). (c) 2004 Elsevier B.V. All rights reserved Daha fazlası Daha az

Genç, Ayten | Bakırcı, Büşra

Article | 2015 | Water Science and Technology71 ( 8 ) , pp.1196 - 1202

The effect of pulsed voltage application on energy consumption during electrocoagulation was investigated. Three voltage profiles having the same arithmetic average with respect to time were applied to the electrodes. The specific energy consumption for these profiles were evaluated and analyzed together with oil removal efficiencies. The effects of applied voltages, electrode materials, electrode configurations, and pH on oil removal efficiency were determined. Electrocoagulation experiments were performed by using synthetic and real wastewater samples. The pulsed voltages saved energy during the electrocoagulation process. In cont . . .inuous operation, energy saving was as high as 48%. Aluminum electrodes used for the treatment of emulsified oils resulted in higher oil removal efficiencies in comparison with stainless steel and iron electrodes. When the electrodes gap was less than 1 cm, higher oil removal efficiencies were obtained. The highest oil removal efficiencies were 95% and 35% for the batch and continuous operating modes, respectively. © IWA Publishing 2015 Daha fazlası Daha az

Kajama, Mohammed Nasir | Yıldırım, Yılmaz | Taura, Usman Habu | Grema, Alhaji Shehu | Abdulrahman, Shehu

Article | 2018 | NANO HYBRIDS AND COMPOSITES21 , pp.43 - 52

A dip-coating technique was applied to prepare a selective membrane on a commercial ceramic mesoporous support. Single gas components used for permeance and selectivity were CH4, CO2, H-2, He, N-2, and O-2 (BOC UK) with at least 99.999 (% v/v) purity. The permeances and selectivities were obtained at room temperature and transmembrane pressure differences between 0.05 up to 5.0 barg. Gas permeation experiments showed the permeance of CO2 to be strongly influenced by surface diffusion mechanism. Single gas experiment showed linear flow dependence on the inverse square root of molecular weight at room temperature and 1.0 barg. The sin . . .gle gas selectivities were found to be higher than the ideal Knudsen separation mechanism. The highest CO2/CH4 selectivity value of 24.07 was obtained at 0.7 barg and room temperature Daha fazlası Daha az

Çakmakçı, Mehmet | Kınacı, Cumali | Bayramoğlu, Mahmut | Yıldırım, Yılmaz

Article | 2010 | Expert Systems with Applications37 ( 2 ) , pp.1369 - 1373

Effluent iron concentration is an important water quality criterion used for the assessment of the performance of rapid sand filters, in addition to other criteria. This study deals with the prediction of effluent iron concentrations by adaptive neuro-fuzzy (ANFIS) model with input parameters including filter hydraulic loading rate, influent iron concentration, bed porosity and operation time. With trying various types of membership functions, two rule base generation methods, namely subtractive clustering and grid partition were used for a first order Sugeno type inference system. Models were evaluated using root mean squared error . . . (RMSE), index of agreement (IA) and R2 as statistical performance parameters. The fit between experimental results and model outputs showed good agreement for tap water and deionized water; testing RMSE values were 36.33 and 7.66 µg/L, the IA values were 0.996 and 0.971, and R2 values were 0.99 and 0.89, respectively. It was concluded that neuro-fuzzy modeling may be successfully used to predict effluent iron concentration in sand filtration. © 2009 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Yıldırım, Yılmaz | Demircioğlu, Nuhi | Kobya, Mehmet | Bayramoğlu, Mahmut

Article | 2002 | Environmental Pollution118 ( 3 ) , pp.411 - 417

A non-linear simple air-quality model was developed by applying the continuity equation for the air control volume over Erzurum city center and tested using daily average values of SO2 and meteorological data obtained during the winter seasons in Erzurum, Turkey from 1994 to 1998. Model parameters are estimated by non-linear regression analysis. Agreement between model predictions and measured data was found very satisfactory with standard deviations less than 20 µg/m3. © 2002 Elsevier Science Ltd. All rights reserved.

Yıldırım, Yılmaz | Hughes, Ronald

Article | 2003 | Process Safety and Environmental Protection: Transactions of the Institution of Chemical Engineers, Part B81 ( 4 ) , pp.257 - 261

In this investigation, the preparation and gas selectivity characteristics of an 'ultrafine' composite ceramic membrane are reported. A dip-coating technique was used to prepare a thin selective membrane on a commercially available ceramic macroporous filter (SCT, France). The permeabilities of H2, N2 and CO2 were measured at temperatures of 25-470°C and average pressures of 1-2 bar. The separation of CO2/N2 binary mixtures was also performed. The separation factors for CO2 were found to be higher than that of the Knudsen separation mechanism at room and high temperature. The potential applications of these membranes to CO2 separati . . .on at these temperatures are discussed on the basis of measured selectivity values Daha fazlası Daha az

Yıldırım, Yılmaz | Hughes, Ronald

Article | 2002 | PROCESS SAFETY AND ENVIRONMENTAL PROTECTION80 ( B3 ) , pp.159 - 164

Catalytic inorganic membrane preparation and the catalytic oxidation of o-xylene contained in air streams on catalytic membrane tubes are presented in this study. Boehmite prepared sols were deposited onto porous alumina tubes from the outside using a filtration coating technique. The coatings were characterized by nitrogen gas permeations at the same temperatures used for the o-xylene experiments. Single gas permeabilities indicated a best separation factor for the modified membrane for H-2/N-2 of 3.6, which is very close to the Knudsen value. Pt loading was estimated as 1.6%w/w based on membrane material weight by using both weigh . . .ing and atomic absorption spectrophotometry (AAS) methods. O-ylene catalytic oxidation of o-xylene contained in air streams with concentrations between 0.146-0.220% (v/v) was carried out in a catalytic membrane reactor at temperatures between 150-290degreesC and 97% conversion was achieved for 0.146% o-xylene in air at a temperature of 285degreesC Daha fazlası Daha az