1,721,294 research outputs found
Selective and Sensitive Voltammetric Determination of Dopamine in Blood by Electrochemically Treated Pencil Graphite Electrodes
No full textWOS: 000272115100011Preparation of electrochemically treated pencil graphite (ETPG) electrode and its application for the determination of DA in the presence of ascorbic (AA) and uric (UA) acids were investigated. Several important parameters were worked to control the performance of the ETPG electrode which showed a high selectivity and sensitivity toward DA. A linear relationship was obtained for dopamine (DA) over the concentration range of 0.01 and 5.0 mu M with a detection limit of 0.31 nM in the presence of AA and UA. The fabrication reproducibility of the ETPG electrodes (n = 10) showed an acceptable reproducibility with a RSD of 2.0% for 5.0 mu M DA. The determination of DA in blood serum without any pretreatment and dilution has been reported for the first time in this work.Anadolu University Research Projects Commission [031064]; Tubitak Directorate of Human Resources Development (TUBITAK-BAYG)Financial support of Anadolu University Research Projects Commission (Project No: 031064) is gratefully acknowledged. Ali Ozcan expresses his gratitude to Tubitak Directorate of Human Resources Development (TUBITAK-BAYG) for the fellowship
Electrochemical investigation of the effects of V(V) and sulfuric acid concentrations on positive electrolyte for vanadium redox flow battery
No full text1st International Symposium on Materials for Energy Storage and Conversion (ESC-IS) -- SEP 07-09, 2015 -- Middle E Tech Univ, Ankara, TURKEYWOS: 0003783594000210 In this study, the concentration effects of sulfuric acid solution and V(V) on positive electrolyte component of vanadium redox batteries were investigated by cyclic voltammetry and electrochemical impedance spectroscopy with pencil graphite working electrode for the first time. The current and redox capacity values of the oxidation and reduction peaks were determined by cyclic voltammetry. The optimum scanning rate and sulfuric acid concentration were at 20 mV s(-1) and 5.0 M, respectively. The current and capacity values of the anodic and cathodic peaks were found to increase but the charge transfer resistance decreased with increasing sulfuric acid concentration. When the concentration of V(V) was increased from 0.04 M to 2.0 M, the current and capacity values of the anodic and cathodic peaks increased. The charge transfer resistance also decreased with increasing the concentration of V(V), as expected
Complete removal of the insecticide azinphos-methyl from water by the electro-Fenton method - A kinetic and mechanistic study
No full textWOS: 000315426700046PubMed ID: 23276423The removal of organophosphorous insecticide azinphos-methyl (AZPM) from water has been investigated by the electro-Fenton method which produces hydroxyl radicals electrocatalytically. The reaction between these radicals and AZPM has led to the oxidation of AZPM up to carbon dioxide and inorganic ions indicating its complete removal from water. The oxidation kinetics was fitted to pseudo-first order reaction and absolute rate constant of the second order reaction kinetic was determined as (6.82 +/- 0.18) x 10(9) M-1 s(-1) by using competitive kinetics method. The oxidation of AZPM by hydroxyl radicals leads to the formation of different intermediates species; such as aromatic derivatives, short-chain carboxylic acids and inorganic ions as end products. The identification and quantification of these intermediates were deeply investigated by HPLC, GC-MS and ion chromatography analyses. Based on the identified intermediates, a general oxidation mechanism was proposed. Mineralization ability of the process was also tested by using aqueous AZPM solutions and its commercial formulation, Gusathion M WP 25 (GMWP25). Mineralization efficiency was followed by the chemical oxygen demand (COD) analysis of treated solutions. The overall mineralization of synthetic AZPM solution and that of commercial formulation at the end of treatment highlights the outstanding mineralization power of the electro-Fenton proces
Anti-corrosive properties of polyaniline, poly(2-toluidine), and poly(aniline-co-2-toluidine) coatings on stainless steel
No full textWOS: 000248465700001This study examines the use of polyaniline (PANi), poly(2-toluidine) (PT), and poly(aniline-co-2-toluidine) (co-PT) for corrosion protection of 304-stainless steel (SS) in 0.5 M HCl solution. The PANi, PT, and co-PT coatings were synthesized on SS substrates under cyclic voltammetric (CV) conditions from acetonitrile solution using tetrabuthylammonium perchlorate (TBAP) as supporting electrolyte and perchloric acid (HClO4) as acid. These coatings were characterized by CV, FTIR, and UV-vis spectroscopy. The ability of PANi, PT, and co-PT to serve as corrosion protective coatings for SS was examined by open circuit potential-time (E-ocp-time), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. The results of this study reveal that PANi, PT, and co-PT acts as corrosion protective coatings on SS and every coating gives protection efficiency of greater than 80% after 48 h of immersion in corrosive test solutio
Corrosion inhibition of stainless steel by polyaniline, poly(2-chloroaniline), and poly (aniline-co-2-chloroaniline) in HCl
No full textWOS: 000241204000008Polyaniline (PANT), poly(2-chloroaniline) (PCIANi), and poly(aniline-co-2-chloroaniline) (co-PCIANi) films were synthesized by electrochemical deposition on 304-stainless steel (SS) from an acetonitrile solution. The structural properties of these polymer films were characterized by spectroscopic (FTIR and UV-vis) and electrochemical (cyclic voltammetry) methods. Open circuit potential-time (E-ocp - time) curves, potentiodynamic polarization, and electrochemical impedance (EIS) measurements showed that these films have significant protective performance against corrosion of SS in 0.5 M HCl solution. It was found that co-PCIANi film has acted as a passivator as well as barrier for cathodic reduction reaction in a similar manner as PANT film. However, PCIANi film has behaved only as barrier for corrosion protection of SS in 0.5 M HC
Non-enzymatic glucose biosensor based on overoxidized polypyrrole nanofiber electrode modified with cobalt(II) phthalocyanine tetrasulfonate
No full textWOS: 000261262000002PubMed ID: 18599285An enzymeless biosensor, based on electrode position of overoxidized polypyrrole nanofiber onto pencil graphite electrode and modified with cobalt(II) phthalocyanine tetrasulfonate (CoPcTS), was investigated in this study. CoPcTS showed electrocatalytic activity for the oxidation of glucose in alkaline solution. The electrochemical performance of the modified electrodes was investigated by differential pulse voltammetric (DPV) method. The resulting biosensor exhibited excellent performance for glucose determination with a wide linear range (0.25-20 mM), a highly reproducible response (R.S.D. of 2.7%), low percentage of the interferences and long-term stability. The calculated detection limit was 0.1 mM at 3 sigma. in order to verify the reliability of the biosensor, it was applied to the determination of glucose in serum samples. The results were satisfactory and agreed closely with those measured in a hospitalAnadolu University Research Found [031064, 051060]Financial support of Anadolu University Research Found (Project Nos.: 031064 and 051060) is gratefully acknowledged. YS would like to thank Prof. Dr. Servet Turan and Res. Asst. Hilmi Yurdakul for taking the SEM pictures of the polymer films
Preparation of selective and sensitive electrochemically treated pencil graphite electrodes for the determination of uric acid in urine and blood serum
No full textWOS: 000279095200018PubMed ID: 20452760In this study, the preparation of electrochemically treated pencil graphite (ETPG) electrodes in the mixture of lithium perchlorate and sodium carbonate solutions was investigated for the first time in the literature. The prepared ETPG electrodes showed high selectivity and sensitivity for uric acid (UA) oxidation over ascorbic acid and dopamine. Differential pulse voltammetry (DPV) was used as electrochemical method. The parameters affecting the UA oxidation were investigated. The optimal pH for UA oxidation was determined as 2. The adsorption of UA on ETPG surface reached saturation in 180 s. The oxidation peak current values versus UA concentration at the ETPG electrode showed linearity in the range from 0.05 mu M to 10.0 mu M (R-2 = 0.9962) with a detection limit of 1.5 nM (S/N=3). The oxidation peak of UA on the EITG electrode did not show any significant change in the presence of certain interferents except bovine serum albumin. The prepared electrodes showed good fabrication reproducibility. The analytical applications of the prepared electrodes were tested by using human urine and blood serum samples. The recovery results of different amounts of UA in urine were varied between 98.6% and 106.4% implying no matrix effect. It was observed that the standard addition method was more satisfactory in the case of blood serum samplesAnadolu University Research Projects Commission [031064]; Tubitak Directorate of Human Resources Development (TUBITAK-BAYG)Financial support of Anadolu University Research Projects Commission (Project No: 031064) is gratefully acknowledged. Ali Ozcan expresses his gratitude to Tubitak Directorate of Human Resources Development (TUBITAK-BAYG) for the fellowship
Determination of paracetamol based on electropolymerized-molecularly imprinted polypyrrole modified pencil graphite electrode
No full textWOS: 000251228600009Preparation of a molecularly imprinted polymer (MIP) film and its recognition property for paracetamol are investigated. The polypyrrole (PPy) film was prepared by the cyclic voltammetric deposition of pyrrole (Py) in the presence of a supporting electrolyte (LiClO4) with and without a template molecule (paracetamol) through on a pencil graphite electrode (PGE). The performance of the imprinted and non-imprinted (NIP) films was evaluated by differential pulse voltammetry (DPV). Several important parameters controlling the performance of the PPy was investigated and optimized. The molecularly imprinted film exhibited a high selectivity and sensitivity toward paracetamol. The calibration curve for the DPV peak current observed for paracetamol oxidation versus paracetamol concentration at MIP electrode shows two linear regions. The first region demonstrates linearity over a concentration range of 5 mu M to 0.50 mM with a correlation coefficient of 0.996. The slope of the second linear region was smaller than the first region's slope with a wide concentration range of 1.25-4.5 mM (R-2 = 0.990). The detection limit (3 sigma) of paracetamol is 7.9 x 10(-7) M (S/N = 3). Molecularly imprinted polypyrrole modified pencil graphite electrode showed a stable and reproducible response without any influence of interferents commonly existing in pharmaceutical sample
Corrosion performance of self-doped sulfonated polypyrrole
No full textWOS: 000241306000005Electrodeposition of sulfonated polypyrrole (SPPy) on 304-stainless steel (SS) was achived in fluorosulfonic acid (FSO3H)/acetonitrile medium using potentiostatic techniques. Adherent and homogeneous SPPy films were obtained. The corrosion behavior of stainless steel with sulfonated PPy coatings in 0.5 M hydrochloric acid solutions, were investigated by potentiodynamic polarization technique, open circuit potential-time curves and electrochemical impedance spectroscopy technique (EIS). It was found that the sulfonated PPy prepared in the presence of 10 mM FSo(3)H (SPPy)1 could provide much better protection than sulfonated PPy prepared in the presence of 50 mM FSo(3)H (SPPy)2. Polarization results showed that (SPPy)1 inhibits the pitting corrosion of SS while EIS measurement shows that both coating gives protection efficiency of greater than 90% after 48 h of immersion time in corrosive test solutio
One-step potentiostatic codeposition and electrochemical studies of poly(1-pyrenyl)-2,5-di(2-thienyl)pyrrole-co-pyrrole) film for electrochemical supercapacitors
Full text linkWOS: 000440654100002In this paper, we report a simple, low-cost, and environmentally friendly electrochemical method to obtain a novel copolymer consisting of l-pyrenyl-2,5-di(2-thienyl)pyrrole and pyrrole on a pencil graphite electrode (PGE). Poly(1-pyrenyl)-2,5-di(2-thienyl)pyrrole-co-pyrrole) that is P(PyrPy-co-Py) film was prepared by one-step potentiostatic codeposition in an ethanol solution containing PyrPy and Py monomers for supercapacitor applications. The electrodeposition of homopolymer and copolymer modified electrodes was carried out on the surface of the PGE via chronocoulometry. For comparison, P(Py)/PGE and P(PyrPy)/PGE were also electrochemically synthesized under the same reaction conditions. The surface morphologies of all the electrode materials were analyzed by field emission scanning electron microscopy. The capacitive properties of the modified PGEs were investigated in 1 M H2SO4 electrolyte solution by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge methods. Compared with P(Py)/PGE and P(PyrPy)/PGE, the P(PyrPy-co-Py)/PGE composite exhibited the best electrochemical behavior and had the highest specific capacitance value of 397. 18 F g(-1) in 1 M H-2 SO4 at a scan rate of 2 mV s(-1). These results indicated that this modified electrode can be used as an electrode material for electrochemical supercapacitors.Anadolu University Research Projects Commission [1401F016]Financial support from the Anadolu University Research Projects Commission (Project No.: 1401F016) is gratefully acknowledged
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