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Öğe Corrosion behavior of mild steel in the presence of scale inhibitor in sulfuric acid solution(MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011) Surme, Yavuz; Gurten, A. Ali; Bayol, EmelSurfactants such as non-ionic polyethylene glycol tert-octylphenyl ether (Triton X-114) have been studied as efficient corrosion inhibitors in acid medium. In this study inhibition performance of Triton X-114 has been evaluated as corrosion inhibitor for mild steel in 0.5 mol l(-1) H(2)SO(4). The electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and linear polarization (LPR) techniques has been applied to determine the electrochemical behaviour of Triton X-114. The maximum efficiency of Triton X-114 was found as 96% at the concentration 5.0 x 10(-5) mol l(-1). The adsorption isotherm of inhibitor on the mild steel surface was found to be in a good agreement with the Langmuir and the standard free energy value (Delta G (ads) (A degrees) ) was calculated as -50.1 kJ mol(-1), which shows that adsorption of Triton X-114 on the mild steel surface improves the inhibition characteristics in 0.5 M H(2)SO(4).Öğe Effect of hyamine on electrochemical behaviour of brass alloy in HNO3 solution(SPRINGER INTERNATIONAL PUBLISHING AG, 2013) Ozkir, Demet; Bayol, Emel; Gurten, A. Ali; Surme, Yavuz; Kandemirli, FatmaThe electrochemical behaviours of a brass alloy in 0.1 M nitric acid, including the hyamine inhibitor with concentrations between 2.5 x 10(-4) M and 1.0 x 10(-5) M, were studied. For this purpose, potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR) techniques, and flame atomic absorption spectroscopy (FAAS) were utilised. The inhibitor molecules adsorbed on the brass surface were calculated to be in good agreement with the Langmuir adsorption isotherm and the standard free enthalpy of adsorption (Delta G (ads) (a similar to) ). Hyamine effectively improved the corrosion inhibition of brass and acted as a mixed-type inhibitor on alloy surfaces. The surface morphology of the alloy was also clarified by optical microscopic and SEM techniques. A theoretical study of the corrosion inhibition efficiency of hyamine molecule was carried out using density functional theory (DFT) at the B3LYP/6-311G(d,p) basis set level. (C) 2012 Institute of Chemistry, Slovak Academy of SciencesÖğe Effect of the temperature and mobile phase composition on the retention behavior of nitroanilines on ligand-exchange stationary phase(ELSEVIER SCIENCE BV, 2006) Gurten, A. Ali; Ucan, Mustafa; Abdullah, Meysun I.; Ayar, AhmetThis paper deals with the separation of isomers of nitroaniline by liquid chromatography using the ligand-exchange technique. The chromatographic separations were performed on the ligand-exchanger sporopollenin. The sporopollenin used as support of stationary phase was modified with carboxylated-ethylenediamine matrix and was loaded with cobalt(II) ions. Using the column packed with cobalt(II) loaded carboxylated diaminoethyl sporopollenin [Co(II)-CDA-E-S], the retention behavior of 3- and 4-nitroanilines was investigated. The mobile phase used, was a mixture of 0.05 M NH4OH in ethanol-water. The resolution was strongly affected by the presence of ammonium hydroxide in the mobile phase and a concentration of 0.05 M was shown to be necessary for the separation of analytes. To study the effects of temperature on the resolution. column runs were also performed at various temperatures (15-60 degrees C). With increasing temperature. a decreased interaction between the solutes and the ligand-exchanger was observed. Consequently. the best results were obtained using a mixture of 0.05M NH4OH in ethanol-water (10:90. v/v) as the mobile phase at a column temperature of 35 degrees C. Ligand-exchange chromatography on the Co(II)-CDAE-S could be a useful alternative method for the separation of nitroaniline. (c) 2005 Elsevier B.V. All rights reserved.Öğe Electrodeposition, characterization and long term stability of NiW and NiWZn coatings on copper substrate in alkaline solution(KOREAN INST METALS MATERIALS, 2013) Surme, Yavuz; Gurten, A. Ali; Kayakirilmaz, KadriyeThis paper describes the electrodeposition of Ni, NiW and NiWZn coatings onto copper surfaces from electrolyte solutions containing Na3C6H5O7, Na2WO4, NiSO4 and ZnSO4. The electrocatalytic effects of electrodeposited coatings were investigated for hydrogen evolution reactions in 1 M NaOH solution. Surface characterization studies were carried out by energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy and cross-section analysis. The effect of operating conditions on the chemical composition, microstructure and electrocatalytic properties of Ni-W coatings was studied. The Zn ions were used to improve the active surface area and catalytic activity of the electrodeposited surface. The electrocatalytic activity of NiW and NiWZn coated electrodes for the hydrogen evolution reaction in alkaline solution was compared with that of an electrodeposited Ni electrode and copper substrate by using cathodic polarization curves and electrochemical impedance spectroscopy techniques over 96 h of electrolysis. The results proved that the NiWZn coated electrode showed better electrocatalytic activity and durability than bare Cu, Ni and NiW coatings.Öğe Influence of polyvinylpyrrolidone on rebar corrosion in sulphate solution(TECHNO-PRESS, 2009) Gurten, A. Ali; Bayol, Emel; Kayakirilmaz, Kadriye; Erbil, MehmetThis paper reports the results of an experimental investigation of the polyvinylpyrrolidone (PVP) influence on the steel reinforcement corrosion and compressive strength of concretes in sulphate medium. The effect of admixture of PVP in concrete on the corrosion resistance of steel reinforced concrete was assessed by measuring electrochemical test during 60 days immersion in two different external solutions. AC impedance spectrum indicated that the resistance of PVP mixed electrodes were higher than those without PVP. The compressive strength of concrete specimens containing PVP was measured and an increase of 190%similar to 24% was observed.Öğe Interactions of some Schiff base compounds with mild steel surface in hydrochloric acid solution(ELSEVIER SCIENCE SA, 2008) Bayol, Emel; Gurten, Tijen; Gurten, A. Ali; Erbil, MehmetThe inhibition effect of the Schiff bases N,N'-bis(salicylidene)-1,2-etliylenedianiine (Salen), N,N'-bis(5-methoxysalicylidene)-1,2-ethylenediamine (MeO-Salen) and N,N'-bis(5-nitrosalicylidene)-1,2ethylenediamine (NO(2)-Salen) on the corrosion of the mild steel in 1.0M HCl has been studied by electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR) and Tafel polarisation measurements. Maximum inhibition for MeO-Salen was obtained. Results showed that the inhibition efficiency have increased when the concentration of the Schiff bases have increased. Polarisation curves revealed that the Schiff bases acted as anodic inhibitors. The surface adsorption of the Schiff bases has lead to a decrease in the double layer capacitance and to an increase in polarisation resistance. The inhibitor performance depended strongly on the type of functional groups on benzene ring. The adsorption process is spontaneous one and follows Langmuir adsorption isotherm model. Scanning electron microscopy (SEM) has been applied to identify the surface morphology of the mild steel both in the absence and presence of the Schiff base molecules. (C) 2008 Elsevier B.V. All rights reserved.Öğe On the removal of some phenolic compounds from aqueous solutions by using a sporopollenin-based ligand-exchange fixed bed - Isotherm analysis(ELSEVIER SCIENCE BV, 2008) Ayar, Ahmet; Gursal, Selpic; Gurten, A. Ali; Gezici, OrhanSingle component adsorption of phenol and 2-, 3- and 4-nitrophenol from water was studied under dynamic column conditions by using a carboxymethyl diaminoethane sporopollenin in a cobalt ion-loaded form, Co(II)-CDAE-S, as solid phase. Adsorption isotherm data were acquired by frontal analysis for five plateau concentrations ranged from 1.25 x 10(-5) to 2.00x 10(-4) mol l(-1). The studied ligand-exchange sporopollenin resin showed a selective adsorptive nature within the group of studied nitrophenols, and the nature of phenols' adsorption on the Co(II)-CDAE-S was analyzed in terms of specific bindings by using Scatchard plot analysis. In light of the Scatchard plot analysis, the adsorption of examined compounds was mainly attributed to the specific bindings based on the ligand-exchange matrix of the studied adsorbent. The nitro-substituted phenols were found to be less strongly adsorbed than the phenol, and both binding strength and theoretical saturation capacity had an obvious relationship with the position of nitro substituent: The theoretical saturation capacities calculated from applied isotherm models exhibited an increase in the order of phenol < 4-nitrophenol < 3-nitrophenol < 2-nitrophenol, whereas a reverse order was showed for binding strengths.Öğe Role of polyethylene glycol tert-octylphenyl ether on corrosion behaviour of mild steel in acidic solution(TAYLOR & FRANCIS LTD, 2009) Surme, Y.; Gurten, A. AliIn recent years, polymeric surfactants have been investigated as efficient corrosion inhibitors for iron in acidic media. In this study, the inhibition performance of polyethylene glycol tert-octylphenyl ether (Triton X-114) for the corrosion of iron in 1M HCl solution has been evaluated. Potentiodynamic polarisation, electrochemical impedance spectroscopy, linear polarisation resistance techniques and long term experiments were used to achieve electrochemical studies. The effect of polyethylene glycol tert-octylphenyl ether on cathodic hydrogen evolution reaction was also investigated. The inhibition efficiency has increased with increasing inhibitor concentration. The standard free energy of adsorption (Delta G degrees(ads)) was calculated. The inhibitor adsorbed on the iron surface was found to be in a good agreement with the Langmuir adsorption isotherm. Polyethylene glycol tert-octylphenyl ether has improved the passivation characteristics of mild steel and inhibited the corrosion effectively in short time tests. The corrosion behaviour of mild steel was also supported by micrographing of the iron surfaces in 1M HCl solution with or without inhibitor.Öğe Systematic corrosion investigation of various Cu-Sn alloys electrodeposited on mild steel in acidic solution: Dependence of alloy composition(ELSEVIER SCIENCE SA, 2009) Surme, Yavuz; Gurten, A. Ali; Bayol, Emel; Ersoy, ErsayCopper-tin alloy films were galvanostatically electrodeposited on the mild steel (MS) by combining the different amount of Cu and Sri electrolytes at a constant temperature (55 degrees C) and pH (3.5). Alloy films were characterized by using the energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and micrographing techniques. Corrosion behaviours were evaluated with electrochemical impedance spectrometry (EIS) and electrochemical polarization measurements Time gradient of electrolysis process was adjusted to obtain same thickness of investigated alloys on MS. The systematic corrosion investigation of various Cu(x)-Sn(100-x) (x = 0-100) alloy depositions on MS substrate were carried out in 0.1 M sulphuric acid medium. Results indicate that the corrosion resistance of the alloy coatings depended on the alloy composition, and the corrosion resistance increased at Cu-Sn alloy deposits in proportion to Sri ratio. (C) 2009 Elsevier B.V All rights reserved.Öğe The effect of temperature and concentration on the inhibition of acid corrosion of carbon steel by newly synthesized Schiff base(ELSEVIER SCIENCE INC, 2015) Gurten, A. Ali; Keles, Hulya; Bayol, Emel; Kandemirli, FatmaInhibition effect of Schiff base namely 1-(2-hydroxybenzylidene)-3-(2,5-dioxoimidazolidin-4-yl) urea (ALS) was studied on carbon steel corrosion in 1.0 M HCl by using the electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and linear polarization (LPR) and quantum chemical study. The values of activation energy (E-a), equilibrium constant (K-ads), adsorption free energy Delta G(ads)(o), adsorption enthalpy Delta H-ads(o) and adsorption entropy Delta S-ads(o) were discussed. The adsorption of inhibitor on metal followed Langmuir's adsorption isotherm. The thermodynamic parameters of adsorption reveal that there is a strong interaction between inhibitor and carbon steel. The highest inhibition efficiency was observed 5.0 x 10(-4) M ALS concentration at 318 K. SEM and EDX observations confirmed the existence of protective inhibitor film on metal surface. Quantum chemical study supports the comparative inhibition effect of ALS. (C) 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.Öğe The effect of thiosemicarbazide on corrosion resistance of steel reinforcement in concrete(ELSEVIER SCI LTD, 2007) Gurten, A. Ali; Kayakirilmaz, Kadriye; Erbil, MehmetThis study describes a laboratory investigation of the influence of thiosemicarbazide (TSC) on the corrosion of reinforcing steel and the compressive strength of concrete. The effect of TSC on the corrosion resistance of steel reinforced concrete was evaluated by carrying out electrochemical tests in NaCl and NaCl + TSC solutions for 60 days. Polarisation resistance (R(P)) values of TSC added reinforced concrete were much higher than those without TSC. Similarly, AC impedance spectra revealed that the resistance of TSC mixed electrodes were also quite higher than those without. The compressive strength of concrete specimens containing TSC was measured and an increase of 20-25% was observed. (c) 2005 Elsevier Ltd. All rights reserved.Öğe The inhibition effect of Azure A on mild steel in 1 M HCl. A complete study: Adsorption, temperature, duration and quantum chemical aspects(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Ozkir, Demet; Kayakirilmaz, Kadriye; Bayol, Emel; Gurten, A. Ali; Kandemirli, FatmaIn this study, inhibition effect of Azure A on mild steel in 1.0 M HCl were evaluated by using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and potentiodynamic polarization and scanning electron microscope (SEM) methods. These studies were carried out at different concentrations, temperatures and durations. The inhibitor molecules were chemisorbed on electrode surface according to the Langmuir adsorption isotherm. The quantum chemical calculations were employed to give further insight into the inhibition mechanism of Azure A. (C) 2011 Elsevier Ltd. All rights reserved.Öğe THERMODYNAMIC STUDY AND ELECTROCHEMICAL INVESTIGATION OF CALCEIN AS CORROSION INHIBITOR FOR MILD STEEL IN HYDROCHLORIC ACID SOLUTION(SOC CHILENA QUIMICA, 2013) Ozkir, Demet; Bayol, Emel; Gurten, A. Ali; Surme, YavuzThe corrosion behaviour of mild steel in 1.0 M HCl solution containing different concentrations of Calcein at different temperatures was investigated using the impedance, potentiodynamic polarization and linear polarization techniques. Long term tests were accomplished by hydrogen gas evolution and impedance measurements. The results showed that inhibition efficiency has increased with the inhibitor concentration and temperature increment. The adsorption of the inhibitor on the mild steel surface obeyed the Langmuir isotherm. Activation energy values at concentrations of Calcein were lower than that of uninhibited system. The thermodynamic parameters of adsorption deduced reveal a strong interaction of Calcein on the mild steel surface.
