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Öğe Direct co-deposition of binder-free Cu-biochar-based nonenzymatic disposable sensing element for electrochemical glucose detection(Elsevier, 2023) Larasati, Lucyana D.; Ates, Ayten; Oskay, Kursad OguzThis work is the first attempt to incorporate biochar on a pencil graphite electrode via one-step electrodeposition as a rational route for refining a copper-based biosensor for a high-performance nonenzymatic electrochemical glucose sensor. Biochar undecorated electrode counterpart was also fabricated for comparison. The cyclic voltammetry graph showed that co-deposition with biochar enhanced the electrocatalytic activity toward glucose oxidation in an alkaline medium. The surface morphology of the copper-biochar hybrid coating demonstrated an attractive three-dimensional structure that had not been reported in the literature. The results indicated that the supplied extending surface area due to biochar modification was the controlling factor for the improved electrochemical reactivity for glucose sensing. The amperometric analysis at an optimum potential of +0.70 V showed linear detection ranges from 0.8 & mu;M to 1 mM and from 1 mM to 5 mM, and good characteristics, such as high sensitivity (6214.4 & mu;A mM-1 cm-2), low limit of detection (0.8 & mu;M), a fast response time (less than 2 s), and excellent anti-interference capability toward the oxidation of glucose. The cost-effective and facile fabrication suggests that the prepared glucose-sensing element can be potentially adapted for construction as a disposable.Öğe Effect of Process Parameters on the Electrodeposition of Zinc on 1010 Steel: Central Composite Design Optimization(Esg, 2020) Kul, Mehmet; Oskay, Kursad Oguz; Erden, Fuat; Akca, Erdem; Katirci, Ramazan; Koksal, Erkan; Akinci, EvindarIn the present work, we studied the effect of critical electrogalvanizing parameters on the quality of electrodeposited Zn films. The current density, electrodeposition time, and ZnCl2 concentration of electrolyte were optimized to maximize current efficiency and brightness, and also, to minimize the surface roughness. Importantly, regression models of the response variables were developed. These models could help industrial applications by providing definitive process conditions to obtain Zn coatings at a desired thickness, roughness and brightness with a high current efficiency. First, preliminary studies were conducted to determine the initial levels of the designated factors. Then, the optimization was conducted through the Central Composite Design by Design -Expert (trial version). Upon completion of the optimization, analysis of variance was also performed. The optimum values of current density, coating duration and ZnCl2 concentration were determined as 3.7 A/dm(2), 4.4 minutes, and 50 g/L, respectively, at a thickness of 6 mu m. Finally, a set of Zn films were deposited at this optimum conditions. The characterization of these films showed that the experimental results were in good accordance with model predictions, providing a bright (L*=83.69) and smooth (Ra=0.75 mu m) coating with excellent adhesion to steel substrate (pull-off strength > 29.41 MPa) at a current efficiency of 98.7%.Öğe Electrochemical Energy Storage Capacity of Surface Engineered Renewable Carbon Derived from Industrial Tea Waste by HNO3 and K2CO3(Pleiades Publishing Inc, 2023) Akgul, Gokcen; Oskay, Kursad Oguz; Buldu-Akturk, Merve; Karamustafa, Aysenur; Sozer, Sozer; Maden, Tugba Bolat; Erdem, EmreDirect electrical energy storage by supercapacitors is the leading energy storage technology. The performance of supercapacitors depends mainly upon the electrode material constituents. Carbon is the preferred energy storage material for its some main properties such as a large surface area, electrical conductivity, porosity, thermal stability, etc. Sustainable, green, renewable, low-cost and environmentally friendly carbon energy storage materials can be obtained from biomass. A larger surface area and tunable micro-porosity, which are the most important advantages, could be achieved by chemical activation of K2CO3 and HNO3. In this work, the effect of K2CO3 and HNO3 on the porosity and the electrochemical energy storage capacity of carbon derived from biomass made from the industrial tea waste were evaluated. A carbon material with a high performance of energy storage exhibiting 460 F g(-1), with a surface area of 1261 m(2) g(-1), could be developed by activation of K2CO3 in the 1 : 1 optimum ratio (w/w). The HNO3 treatment also increased the capacitance but to a very low degree.Öğe Evaluation of iron containing biochar composites prepared by different preparation methods for H2O2 sensing(Elsevier, 2023) Ates, Ayten; Oskay, Kursad OguzBackground: The procedures employed to prepare the ferrous biochar samples, the iron salts utilized, and their quantities have an effect on the surface characteristics of the material and the types of iron that will develop on the surface.Methods: Iron containing biochar (Fe-BC) samples were prepared using three different preparation methods: Precipitation, Impregnation (IP) and Solid-state (SS). The iron content of the biochar (BC) was varied in a range from 6.5 to 21.0 wt. % by using a SS method that mechanically mixed FeCl3 and hazelnut shell (HS) in solid form.Significant Findings: The XRD, XPS and FT-IR results showed that the magnetite particles (Fe3O4) were mainly formed on the surface of all samples, but their content was strongly dependent on the preparation method and the amount of iron. Additionally, the formation of Fe2O3, Fe2C, FeCO3, and FeOOH species on the surface was determined. The highest surface area and microporosity were obtained for the Fe-BC sample prepared by IP (FeBC-IP):850 m2/g and 0.28 cm3/g, respectively. A novel and fast electrochemical sensing platform for the detection of H2O2 with a broad linear range (0.5-10 mM) and high sensitivity (621 mu A mM-1 cm-2) was fabricated. The findings demonstrate that the non-enzymatic BC-IP sensor is a useful alternative for measuring H2O2.Öğe Improving the Electrochemical Energy Storage Capacity of the Renewable Carbon Derived from Industrial Tea Waste (vol 58, pg 844, 2022)(Pleiades Publishing Inc, 2024) Karamustafa, Aysenur; Sozer, Sozer; Oskay, Kursad Oguz; Buldu-Akturk, Merve; Erdem, Emre; Akgul, GokcenAn Erratum to this paper has been published: https://doi.org/10.1134/S1023193524020113Öğe Optimization of selective leaching of Zn from electric arc furnace steelmaking dust using response surface methodology(ELSEVIER SCIENCE BV, 2015) Kul, Mehmet; Oskay, Kursad Oguz; Simsir, Mehmet; Subutay, Halit; Kirgezen, HabipThe aim of this work is to investigate and optimize the effects of the leaching parameters on the selective leaching of zinc from electric arc furnace steelmaking dust (EAFD). The response surface method was applied on the basis of a three-level Box-Behnken experimental design method for optimization of selective leaching parameters of zinc from EAFD. The leaching recoveries of zinc (Y-Zn) and iron (Y-Fe) were taken as the response variables, where the concentration of sulphuric acid (X-1, mol/L), leaching temperature (X-2, degrees C), leaching time (X-3, min), and liquid/solid ratio (X-4, mL/g) were considered as the independent variables (factors). The mathematical model was proposed. Statistical ANOVA analysis and confirmation tests were applied. A maximum of 79.09% of zinc was recovered while the minimum iron recovery was 4.08% under the optimum conditions of leaching time 56.42 min, H2SO4 concentration 2.35 mol/L, leaching temperature 25 degrees C and liquid/solid ratios. By using ANOVA, the most influential factors on leaching of zinc and iron were determined as H2SO4 concentration and leaching temperature, respectively. The proposed model equations using response surface methodology show good agreement with the experimental data, with correlation coefficients (R-2) of 0.98 for zinc recovery and 0.97 for iron recovery.Öğe OPTIMIZING THE COMPOSITION OF ELECTROPLATED NiCrAl COMPOSITE COATING(YILDIZ TECHNICAL UNIV, 2018) Oskay, Kursad Oguz; Demirel, BilalNiCrAl composite coatings were obtained by electro-deposition under direct current (DC) conditions from a Watt's bath containing suspended Cr, Al particles. Mathematical models were developed to simulate the electroplated composite coating. The models allow composition of the coatings to be predicted. The predicted values obtained were close to the experimental values, indicating the suitability of the models. The prediction made using Response Surface Method (RSM) was also supported by SEM photos. Three-dimensional surface plots were helpful for predicting results by performing only limited set of experiments.Öğe Optimizing the recovery of copper from electroplating rinse bath solution by hollow fiber membrane(IWA PUBLISHING, 2015) Oskay, Kursad Oguz; Kul, MehmetThis study aimed to recover and remove copper from industrial model wastewater solution by non-dispersive solvent extraction (NDSX). Two mathematical models were developed to simulate the performance of an integrated extraction-stripping process, based on the use of hollow fiber contactors using the response surface method. The models allow one to predict the time dependent efficiencies of the two phases involved in individual extraction or stripping processes. The optimal recovery efficiency parameters were determined as 227 g/L of H2SO4 concentration, 1.22 feed/strip ratio, 450 mL/min flow rate (115.9 cm/min. flow velocity) and 15 volume % LIX 84-I concentration in 270 min by central composite design (CCD). At these optimum conditions, the experimental value of recovery efficiency was 95.88%, which was in close agreement with the 97.75% efficiency value predicted by the model. At the end of the process, almost all the copper in the model waste water solution was removed and recovered as CuSO4 center dot 5H(2)O salt, which can be reused in the copper electroplating industry.Öğe Separation and recovery of valuable metals from real mix electroplating wastewater by solvent extraction(ELSEVIER SCIENCE BV, 2015) Kul, Mehmet; Oskay, Kursad OguzRecycling of electroplating wastewater is very important because of the large amounts of wastewater generated, the enormous economic value and large environmental concerns when conventional neutralization precipitation processes are used to dispose of the wastewater. This work describes the recovery of valuable metals from industrial wastewater collected at a galvanizing industrial site using a solvent extraction process. Several extractants such as DEHPA, TBP, LIX 984N-C, Cyanex 272 and Aliquat 336 were tried for the separation and recovery of valuable metals from the wastewater. Optimum extraction parameters for zinc, copper, iron, nickel and chromium were determined as 10% Aliquat 336, 5% LIX 984N-C, 10% DEHPA, 15% LIX 984N-C and 10% Cyanex 272 in kerosene at equilibrium pH 1.45, 1.20, 1.00, 5.25 and 6.00 with 99.6%, 100%, 100%, 99.9% and 100% extraction efficiencies at almost 100% selectivity, respectively. These extraction efficiencies were attained at two extraction stages for zinc, copper and chromium and at one extraction stage for iron and nickel. Copper-loaded LIX 984N-C, iron-loaded DEHPA, nickel-loaded LIX 984N-C and chromium-loaded Cyanex 272 were stripped with 450 g/L, 2 M, 150 g/L and 1 M H2SO4 respective strip solutions with relative 100% stripping efficiencies. A two-stage process stripped the zinc-loaded Aliquat 336 with a 2 M NaOH solution with 100% efficiency. Based on the data, a flow sheet for the separation of the five metal ions is provided. (C) 2015 Elsevier B.V. All rights reserved.
