Yavuz Sürme

Synthesis and characterization of oligosalicylaldehyde-based epoxy resins

The synthesis of a new epoxy resin of oligosalicylaldehyde by the reaction with epichlorohydrin is reported. New resin’s epoxy value and chlorine content were determined and found to be 25% and 1%, respectively. The characterization of the new resin was instrumented by FTIR, 1H NMR, scanning electron microscopy, and thermal gravimetric analyses. TGA results showed that the cured epoxy resin has a good resistance to thermal decomposition. The mass losses of cured epoxy resin were found to be 5%, 10%, 50% at 175°C, 240°C, and 400°C, respectively. On the curing procedure the resin was cured with polyethylenepolyamine at 25 °C for 8 h and 100°C for 1.5 h. The FTIR spectrum of new epoxy resin gave the peak of oxirane ring at ṽ = 918 cm−1.

Role of polyethylene glycol tert-octylphenyl ether on corrosion behaviour of mild steel in acidic solution

Abstract In 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 (ΔG°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.

Corrosion behavior of mild steel in the presence of scale inhibitor in sulfuric acid solution

Surfactants 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 H2SO4. 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 × 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 (ΔGads°) 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 H2SO4.

Determination of direct violet 51 dye in water based on its decolorisation by electrochemical treatment

The decolorisation process of a synthetic textile dye, direct violet 51, was investigated in an aqueous solution using an electrochemical method in a batch electrochemical cell. Graphite electrodes were used as the anode and cathode for the decolorisation process. The parameters such as applied current, initial pH, solution conductivity, interfering ions, and effect of electrodes were optimised. It was found that the dye with an initial concentration of 20 mg L−1 could be removed after 50 min using a current of 100 mA with colour removal of up to 94 %. The UV-VIS spectra of the dye were analysed prior to and after treatment and these confirmed that the conjugated systems were decomposed at a current of 100 mA. The optimised method was successfully applied to real wastewater samples.

Electrodeposition, characterization and long term stability of NiW and NiWZn coatings on copper substrate in alkaline solution

This 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.

Effect of hyamine on electrochemical behaviour of brass alloy in HNO3 solution

The electrochemical behaviours of a brass alloy in 0.1 M nitric acid, including the hyamine inhibitor with concentrations between 2.5 × 10−4 M and 1.0 × 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 (ΔGads∘). 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.

Removal of textile dye Lanaset Red G from waters by electrochemical degradation and spectrophotometric determination

AbstractThe removal of Lanaset Red G, a kind of azo dye, has been studied with graphite electrodes in aqueous solution by electrochemical method. Graphite electrodes were used as anode and cathode in the decolourization process. Concentration of dye molecules in aqueous solution was determined by the ultraviolet-visible spectrophotometric technique. The operational parameters including initial pH, effect on the conductivity and time of electrolysis were optimized. The surface morphology of electrodes was also investigated and found that the surface of anode was affected by electrolysis. The results indicated that for a solution of 50 mg L−1 dye, almost 94% of dye was removed under optimum conditions. The optimized conditions were successfully applied to remove dye molecules present in real textile effluent and lake waters.

Heavy-metal extraction capability of chalcogenoic aminophosphines derived from 1-amino-4-methylpiperazine

Aminophosphine of the type (Ph2PNHR) derived from 1-amino-4-methylpiperazine and its chalcogen derivatives (Ph2P(X)NHR X = S, Se) were used as ligands in solvent extraction of metal picrates such as Cu2+, Ni2+, and Pb2+ from the aqueous to the organic phase. Influence of parameters such as pH of the aqueous phase, ligand concentration in the organic phase, and concentration of the extractant extracted from the aqueous to the organic phase was investigated to determine the ligands’ ability to extract metal ions. Metal picrate extraction was investigated at 25°C using UV-VIS spectrophotometry in dichloromethane in the absence and in the presence of Ph2PNHR and chalcogenides. The extraction results revealed that the extraction percentage of Cu2+, Ni2+, and Pb2+ metals was much higher at lower pH values, indicating an acidity dependent complexation equilibrium.

SIMULTANEOUS PRECONCENTRATION AND DETERMINATION OF Cu2+, Ni2+ AND Cd2+ BY MICELLE MEDIATED EXTRACTION IN FOOD AND WATER SAMPLES

An effective extraction procedure based on the complexation of Cu 2+ , Cd 2+ , and Ni 2+ with dithizone and extraction of these complexes by Tergitol NP-7 surfactant was developed. Micelle mediated extraction parameters such as pH, ligand and surfactant concentration, incubation time and temperature were investigated and optimized. Effects of external and internal interfering ions, linear dynamic range, detection and quantitation limits were examined and determined under optimal conditions. Detection limits were found as 0.5, 1.8 and 2.0 mg L -1 for Cu 2+ , Ni 2+ and Cd 2+ , respectively. Linear dynamic range values were between 0.125-2, 0.125-2.5 and 0.05-1.4 μg mL -1 for Cu 2+ , Ni 2+ and Cd 2+ ions, respectively. Applicability, accuracy and precision of the method were checked with standard reference materials and real sample analyses by analyte addition technique. Finally, optimized method was applied to determine Cu 2+ , Ni 2+ and Cd 2+ contents of standard reference materials, mushrooms and water samples. Quantitative and accurate results were obtained from the analysis of standard reference materials and real samples.

THERMODYNAMIC STUDY AND ELECTROCHEMICAL INVESTIGATION OF CALCEIN AS CORROSION INHIBITOR FOR MILD STEEL IN HYDROCHLORIC ACID SOLUTION

The 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.