Portugaliae Electrochimica Acta 25 (2007) 221-235 PORTUGALIAE ELECTROCHIMICA ACTA Corrosion Inhibition of Mild Steel in Sulphuric Acid Solution (original) (raw)
Related papers
The corrosion inhibition of mild steel in one normal sulphuric acid solution by brij-30 has been studied in relation to the concentration of the inhibitor as well as the temperature using electrochemical polarization (galvanostatic and potentiostatic) techniques. The results were supplemented with scanning electron microscopy and infra-red spectroscopy. All the methods employed are in reasonable agreement. There is no particular relationship of inhibition with concentration and temperatures. The thermodynamic functions of dissolution and adsorption processes were calculated from experimental polarization data and the interpretation of the results is given. Adsorption of Brij-30 was found to follow the Langmuir's adsorption isotherm. Brij-30 is a mixed type of inhibitor.
Use of inhibitor is proven as an efficient and widely accepted corrosion prevention method. Corrosion control of steel is an important activity in technical, economic, environmental and safety terms. This article enumerates several types of inhibitors used to combat corrosion in acidic medium. In this paper, literature on corrosion inhibitors has been reviewed and discussions are made on properties and efficiency of inhibitors. (The prominent features of our work on the mechanism of corrosion inhibitors have been highlighted and in a few cases have tried to predict its mechanism).
The corrosion inhibition of mild steel in one normal sulphuric acid solution by CPB has been studied in relation to the concentration of the inhibitor as well as the temperature using electrochemical polarization (galvanostatic and potentiostatic) techniques. The results were supplemented with scanning electron microscopy and infra-red spectroscopy. All the methods employed are in reasonable agreement. There is no particular relationship of inhibition with concentration and temperatures. The thermodynamic functions of dissolution and adsorption processes were calculated from experimental polarization data and the interpretation of the results are given. Adsorption of CPB was found to follow the Langmuir's adsorption isotherm. Brij-30 is a mixed type of inhibitor.
Portugaliae Electrochimica Acta, 2009
The effect of phenylthiourea as a corrosion inhibitor for low carbon steel at different hydrochloric acid concentrations, different temperatures and fixed speed of electrode rotation, were addressed in this work. Polarization technique was used to evaluate the corrosion rates parameters. The corrosion rate of low carbon steel increases with temperature and follows Arrhenius equation in all acid concentrations in presence and absence of the inhibitor. Detailed thermodynamic parameters of activation (∆H act and ∆S act) for the corrosion reaction were obtained using nonlinear estimation method, while adsorption parameters (∆G ads , ∆H ads and ∆S ads) were obtained using graphical method. Maximum inhibitor efficiency was (96.44%) obtained at 1 M HCl at 333 K and 1 g/L inhibitor concentration.
Journal of Chemical Engineering and Materials Science, 2012
The corrosion inhibition of mild steel in one normal sulphuric acid solution by tetra methyl ammonium bromide (TMAB) has been studied in relation to the concentration of the inhibitor as well as the temperature using electrochemical polarization (galvanostatic and potentiostatic polarizations) techniques. The results were supplemented with scanning electron microcopy and infra-red spectroscopy. All the methods employed are in reasonable agreement. There is no particular relationship of inhibition with concentration and temperatures. The thermodynamic functions of dissolution and adsorption processes were calculated from experimental polarization data and the interpretation of the results are given. Adsorption of TMAB was found to follow the Langmuir's adsorption isotherm. TMAB is a mixed type of inhibitor.
The corrosion inhibition of mild steel in one normal sulphuric acid solution by tetra methyl ammonium bromide (TMAB) has been studied in relation to the concentration of the inhibitor as well as the temperature using electrochemical polarization (galvanostatic and potentiostatic polarizations) techniques. The results were supplemented with scanning electron microcopy and infra-red spectroscopy. All the methods employed are in reasonable agreement. There is no particular relationship of inhibition with concentration and temperatures. The thermodynamic functions of dissolution and adsorption processes were calculated from experimental polarization data and the interpretation of the results are given. Adsorption of TMAB was found to follow the Langmuir's adsorption isotherm. TMAB is a mixed type of inhibitor.
Portugaliae Electrochimica Acta
The present work highlights the results of the application of a green inhibitor for material conservation. The anticorrosive performance of the pectin bio-polymer was established for the corrosion control of mild steel in a 1 M phosphoric acid medium. Electrochemical measurements such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) studies were adopted for the corrosion inhibition studies. The studies were carried out by varying the concentrations of pectin in the temperature range from 303 K to 318 K. Conditions were optimized to get maximum inhibition efficiency. The surface morphology study was done by scanning electron microscope (SEM), and elemental mapping was done using energy dispersive X-ray (EDX) studies to confirm the adsorption and interaction of the inhibitor with the material. Studies showed an increase in the inhibition efficiency with an increase in the concentration of pectin and also in the temperature. Maximum inhibition efficiency of 70% was achieved by the addition of 800 ppm of inhibitor. Pectin acted as a mixed type inhibitor by bringing down both cathodic and anodic reactions. Kinetic and thermodynamic parameters revealed chemical adsorption of pectin onto the mild steel surface. A suitable mechanism was proposed for the adsorption of pectin which was reaffirmed by the surface morphology studies. Pectin emerged as a potential eco-friendly green inhibitor for the corrosion control of mild steel, with economic benefits.
Investigation of Inhibition Effect of Acrylic acid on C-Steel Corrosion in Sulfuric Acid Solutions
Journal of Advances in Chemistry, 2010
Acrylic acid was tested as a corrosion inhibitor for C-steel in 0.5 M H2SO4 using gasometry, weight loss, and galvanostatic polarization techniques. Polymeric film is built up by cyclic voltammetry technique. The potentiodynamic polarization is used to examine the inhibition effect with the coated polymeric film. The data obtained from the different techniques coincide in that acrylic acid is a good mixed-type inhibitor. The inhibition process is based on the adsorption of acrylic acid on the surface of C-steel according to Temkin’s adsorption isotherm. The inhibition efficiency increases with inhibitor concentration and decreases with temperature. The thermodynamic parameters ΔE, ΔH*, ΔS*, and ΔG*ads were calculated to elaborate the mechanism of corrosion inhibition.
Corrosion Science, 2008
The influence of the concentration of adenine (AD), as a safe inhibitor, on the corrosion of low carbon steel (LCS) in aerated 4.0 M H 2 SO 4 solutions was studied. The investigations involved weight loss, potentiodynamic polarization, impedance and electrochemical frequency modulation (EFM) methods. Variations of open-circuit potential (OCP) as a function of time till steady-state potentials were also studied. Measurements were conducted under the influence of various experimental conditions complemented with ex situ EDX examinations of the electrode surface. By using EFM measurements, corrosion current density was determined without prior knowledge of Tafel slopes. Results obtained revealed that together with iodide ion, AD is an effective corrosion inhibitor for LCS corrosion in H 2 SO 4 solutions. Synergism between iodide ion and AD was proposed. Potentiodynamic polarization studies showed that AD alone and the mixture of AD and iodide ions act as mixed-type inhibitors for the corrosion of LCS in 4.0 M H 2 SO 4 solution. The inhibition mechanism involves the electrostatic adsorption of protonated AD molecules on the LCS surface charged with a negative layer of chemisorbed I À ions. An adherent layer of inhibitor is postulated to account for the protective effect. EDX examinations of the electrode surface confirmed the existence of such adherent layer on the electrode surface. The inhibition efficiency increases with increase in the concentration of AD and immersion time. The potential of zero charge (PZC) of the LCS electrode was determined in 4.0 M H 2 SO 4 solutions in the absence and presence of 0.001 M KI, and the mechanism of adsorption was discussed. The results obtained from chemical and electrochemical measurements were in good agreement.
Investigation of some oleochemicals as green inhibitors on mild steel corrosion in sulfuric acid
Journal of Applied Electrochemistry, 2009
The inhibitive effect of four oleo chemicals (namely; 2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI)), regarded as green inhibitors, were studied for the corrosion protection of mild steel in 0.5 M H2SO4. The methods employed were weight loss, potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopy (SEM) was carried out on the inhibited and uninhibited metal samples to characterize the surface. The purity of synthesized inhibitors was checked by FT-IR and NMR studies. The inhibition efficiency increased with increase in inhibitor concentration, immersion time and decreased with increase in solution temperature. No significant change in IE values was observed with increase in acid concentration. The best performance was obtained for UDI possessing 96.2% inhibition efficiency at 500 ppm concentration. The adsorption of the compounds on the mild steel surface in the presence of sulfuric acid obeyed Langmuir’s adsorption isotherm. The values obtained for free energy of adsorption and heats of adsorption suggest physical adsorption. The addition of inhibitor decreased the entropy of activation suggesting that the inhibitors are more orderly arranged along the mild steel surface. The potentiodynamic polarization data indicate mixed control. The electrochemical impedance study further confirms the formation of a protective layer on the mild steel surface through the inhibitor adsorption.