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    Degradation of Calmagite by H2O2/UV/US, H2O2/US, H2O2, and US process
    (Elsevier, 2022) Menek, Necati; Ugurlar, Ceren; Ucarh, Okan; Karaman, Yeliz; Omanovic, Sasha; Ghasemian, Saloumeh
    1-(1-Hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulfonic acid is known as Calmagite. In this study, the degradation of Calmagite in H2O2/UV/US, H2O2/US, H2O2, and US processes were investigated separately and each was compared among themselves. The concentration of H2O2, initial dye concentration, pH, UV light, and also ultrasonic sound significantly influenced the degradation of Calmagite and these parameters were optimized. For the azo dye tested, more than 98% of degradation in H2O2/UV/US, H2O2/US, and H2O2 processes was reached in 20, 40, and 60 min, respectively in Britton Robinson buffer media at pH = 11.0. The proposed degradation pathways of Calmagite were established from the (OH)-O-center dot mediated degradation of this azo dye. The first-order rate kinetics best fit the degradation of Calmagite. (C) 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University.
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    Electrochemical Behaviour of 5-Methyl-4-(2-Thiazolylazo)-Resorcinol in Micellar Media
    (2021) Karaçelik, Ahmet; Karaman, Yeliz; Topçu, Saim
    In this study, surfactant effects on the spectroscopic and electrochemical behavior of 5-Methyl-4-(2- thiazolylazo)-resorcinol were studied in an aqueous solution at neutral pH. Dodecylpyridinium chloride (DDPC), cetylpyridinium chloride (CPC) (cationic), Triton X100, Tween 20 (nonionic), and sodium dodecyl sulfate (SDS) (anionic), were used in investigation. A large bathochromic shift of absorption maxima of the dye was observed upon the addition of surfactant. Electrochemical reduction of the dye was investigated by cyclic voltammetry (CV). The adsorption-controlled reduction reaction of the dye changed to a semireversible diffusion-controlled reduction peak at -0.43 V by the addition of CPC. Depending on the CPC concentration in the dye solution, the peak potential of the electrode reaction shifted about 120 mV in the cathodic direction and the peak current decreased up to ten times. These changes were interpreted depending on the type and concentration of surfactant present in the solution.
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    Investigation of Catalytic Effect Nitrite on Electrochemical Reduction of Cobalt Dimethylglyoxime Complex by Polarographic and Voltammetric Techniques
    (International Journal of Electrochemical Science, 2014) Menek, Necati; Uçarlı, Okan; Topçu, Saim; Zeyrekli, Serpil; Karaman, Yeliz
    The voltammetric and polarographic behaviour of Cobalt Dimethylglyoxime (Co-DMG) complex on a hanging mercury drop electrode (HMDE) and static mercury drop electrode (SMDE) has been studied by several techniques including Square wave voltammetry (SWV), Differential pulse polarography (DPP) and stripping techniques. Polarographic and voltammetric curves recorded at HMDE and SMDE provide information about electrode reaction mechanism. Catalytic effect of nitrite on the electrochemical reduction mechanism of the complex have been explained.
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    Investigation of Electrochemical Behavior of 2-(5-Bromo-2-Pyridylazo)-5-[N-Propyl-N-(3-Sulfopropyl)Amino] Phenol Disodium Salt Dihydrate
    (Electrochemical Soc Inc, 2012) Karaman, Yeliz; Menek, Necati
    The voltammetric and polarographic behavior of 2-(5-bromo-2-pyridylazo)-5-[N-propyl-N-(3-sulfopropyl)amino] phenol disodium salt dihydrate (5-Br-PAPS) at a hanging mercury drop electrode (HMDE) and static mercury drop electrode (SMDE) has been studied by several techniques including square-wave voltammetry (SWV), differential pulse polarography (DPP), direct current polarography (DCP) and cyclic voltammetry (CV). Current-potential curves recorded at a HMDE and SMDE provide information about the electrode reaction mechanism. The electrochemical reduction mechanism of the azo compound is suggested using SWV, DPP, DCP and CV techniques in different electrolyte media. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.031210jes] All rights reserved.
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    Investigation of Electrochemical Behavior of 4-(2-Pyridylazo)resorcinol and its Cu2+ Complex by Using Polarographic and Voltammetric Techniques
    (Elsevier, 2021) Karaman, Yeliz; Menek, Necati
    In this work, the electrochemical behavior of 4-(2-pyridylazo)resorcinol (PAR) azo dye was studied in Britton-Robinson (BR) buffer (pH 2.0-12.0) media by employing square wave voltammetry (SWV), differential pulse polarography (DPP), direct current polarography (DCP) and cyclic voltammetry (CV) techniques. From the polarographic and voltammetric results, the electrochemical reaction mechanism of the azo dye has been proposed. At the same time, the electrochemical behavior of the copper(II) complex with PAR was investigated by using SWV in 0.1 M KNO3 supporting electrolyte. SWV behavior of Cu(II)-PAR complex at different metal and ligand concentrations have been determined in KNO3 supporting electrolyte media. The metal:ligand molar ratio and stability constant of the Cu(II)-PAR complex were determined to be 1:2 and 5.42x10(10), respectively.
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    Investigation of electrochemical behavior of Calmagite at a glassy carbon electrode
    (Elsevier Sci Ltd, 2014) Karaman, Yeliz
    The voltammetric behavior of 1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulfonic acid (Calmagite) has been studied by square-wave voltammetry (SWV), differential pulse voltammetry (DPV), cyclic voltammetry (CV) and direct current voltammetry (DCV) in different electrolyte media. The voltammograms recorded at a glassy carbon electrode (GCE) exhibit one cathodic peak, corresponding to the two-step four-electron reduction process of azo compound. The observed shift of the compound reduction peaks to more negative potentials with increasing pH indicates that hydrogen ions are involved in the electrode reaction. The effect of scan rate and pH on the reduction peaks has been studied. From the voltammetric data, the electrochemical reaction mechanism of the azo compound has been suggested. (C) 2014 Elsevier Ltd. All rights reserved.
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    Investigation of Electrochemical Behavior of Mordant Dye (CI 17135)
    (Elsevier, 2021) Zeyrekli, Serpil; Karaman, Yeliz; Menek, Necati
    In this study, the electrochemical behavior of Mordant dye (C.I. 17135) was investigated in BrittonRobinson (BR) buffer (pH 2.0-12.0) media by using different techniques, which are square wave voltammetry (SWV), cyclic voltammetry (CV), differential pulse polarography (DPP), direct current polarography (DCP) techniques. The polarograms and voltammograms of the dye on a static mercury drop electrode (SMDE) and hanging mercury drop electrode (HMDE) show one reduction peak corresponding to the two-step four electron electrode reaction mechanism. In SW voltammograms and DP polarograms of the dye, a broad shoulder peak was seen in the pH range of 2.0 to 12.0, due to the adsorption of the azo dye on the electrode surface. The shift of the peak potentials to more negative values indicate that the protons are involved in the electrode reaction. The effect of scan rate on the reduction peak has been studied at different pH values.
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    Investigation of Electrochemical Behaviour of 3-Allyl-4-Hydroxy-3'-4'- Dimethylazobenzene
    (International Journal of Electrochemical Science, 2013) Menek, Necati; Başaran, Serpil; Karaman, Yeliz; Topçu, Saim
    The reductive voltammetric and polarographic behaviour of the 3-allyl-4-hydroxy-3'-4' dimethylazobenzene at a hanging mercury drop electrode (HMDE) and static mercury drop electrode (SMDE) has been studied in Britton-Robinson (B-R) buffers in the pH range of 2.0-12.0. The 3-allyl-4-hydroxy-3'-4' dimethylazobenzene gave one voltammetric and polarographic peak, corresponding to the reduction of the azo group to hydrazo and amine. The reduction process was found to be dependent on the pH of the supporting electrolyte. The reduction of the azo group to amino group in acidic media and hydrazo step in neutral and basic media was observed. From the observation an electrode reaction mechanism has been suggested for the compound.
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    Investigation of Electrochemical Behaviour of 3-Allyl-4-Hydroxy-3′-4′-Dimethylazobenzene
    (Esg, 2013) Menek, Necati; Basaran, Serpil; Karaman, Yeliz; Topcu, Saim
    The reductive voltammetric and polarographic behaviour of the 3-allyl-4-hydroxy-3'-4'-dimethylazobenzene at a hanging mercury drop electrode (HMDE) and static mercury drop electrode (SMDE) has been studied in Britton-Robinson (B-R) buffers in the pH range of 2.0-12.0. The 3-allyl-4-hydroxy-3'-4'-dimethylazobenzene gave one voltammetric and polarographic peak, corresponding to the reduction of the azo group to hydrazo and amine. The reduction process was found to be dependent on the pH of the supporting electrolyte. The reduction of the azo group to amino group in acidic media and hydrazo step in neutral and basic media was observed. From the observation an electrode reaction mechanism has been suggested for the compound.
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    Investigation of Nickel Ion Release from Stainless Steel Crowns by Square Wave Voltammetry
    (International Journal of Electrochemical Science, 2012) Menek, Necati; Başaran, Serpil; Karaman, Yeliz; Ceylan, Gözlem; Şen Tunç, Emine
    No effort has been made to define nickel magnitude from stainless steel crowns in oral environment. Nickel ions released in sufficient quantities from nickel-containing alloys may induce nickel sensitization or elicit allergic contact dermatitis. In this work nickel ion release from stainless steel crowns in artificial saliva at different days and pH’s has been investigated which is used in pediatric dentistry. Totally 120 stainless steel crowns for primary teeth were immersed to artificial saliva in this study. Nickel in aqueous solutions was determined by square wave voltammetry, using dimethylglyoxime as a complexion agent on mercury electrode. The study revealed that nickel ion release was decreased with increasing pH. Furthermore nickel releasing ratio was decreased in all time periods. Results showed that metal ions released in this experimental condition were well below the critical value to induce allergy and below daily dietary intake level.
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    Voltammetric investigations of 2,2'-azobispyridine zinc(II) and nickel(II) complexes
    (Electrochemical Science Group, 2015) Karaman, Yeliz; Menek, Necati; Bicer, Figen Arslan; Olmez, Halis
    The electrochemical behaviour of 2,2'-Azobispyridine (abpy) has been studied by using voltammetric techniques. From obtained data, electrochemical reaction mechanism of the azo compound has been suggested. At the same time, zinc(II) and nickel(II) complexes of the azo compound have been investigated in different solution media. 50% ethanol-50% KNO3 (0.1M) medium has been chosen as optimum solution medium. The composition of the zinc(II) and nickel(II) abpy complexes has been determined to be 1:2. The optimum conditions favoring the formation of complexes were studied and their stability constants were determined by using square-wave voltammetric technique. © 2015 The Authors.
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    Voltammetric Investigations of 2,2′-Azobispyridine Zinc(II) and Nickel(II) Complexes
    (Elsevier, 2015) Karaman, Yeliz; Menek, Necati; Bicer, Figen Arslan; Olmez, Halis
    The electrochemical behaviour of 2,2'-Azobispyridine (abpy) has been studied by using voltammetric techniques. From obtained data, electrochemical reaction mechanism of the azo compound has been suggested. At the same time, zinc(II) and nickel(II) complexes of the azo compound have been investigated in different solution media. 50% ethanol-50% KNO3 (0.1M) medium has been chosen as optimum solution medium. The composition of the zinc(II) and nickel(II) abpy complexes has been determined to be 1:2. The optimum conditions favoring the formation of complexes were studied and their stability constants were determined by using square-wave voltammetric technique.