PORTUGALIAE ELECTROCHIMICA ACTA Corrosion Inhibition of Mild Steel in 1 M H 2 SO 4 by Polyvinyl Pyrrolidone and Synergistic Iodide Additives (original) (raw)
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Portugaliae Electrochimica Acta, 2008
The corrosion inhibition of mild steel in 1M H 2 SO 4 by polyvinyl pyrrolidone (PVP) and the synergistic effect of iodide ions were investigated using weight loss and hydrogen evolution methods in the temperature range of 30 -60 o C. The corrosion rates of mild steel decreased with the increasing concentration of PVP, while the inhibition efficiency (%I) increased. The inhibition efficiency of PVP decreased with rise in temperature, suggesting a physical adsorption mechanism, which was found to follow Freundlich and Temkin adsorption isotherms. The inhibition mechanism was further collaborated by the values of kinetics/thermodynamic parameters obtained from the experimental data. The inhibiting action of PVP was considerably enhanced in the presence of iodide ions and values of the synergism parameter (S 1 ) obtained point to synergistic interactions between PVP and iodide ions.
Polyvinyl pyrrolidone as a Corrosion Inhibitor for Carbon Steel in HCl
2016
The inhibition effect of the green inhibitor Polyvinyl pyrrolidone (PVP) on the corrosion of carbon steel (C-steel) in 2 M HCl aerated unstirred solutions is investigated. Electrochemical methods (EIS and potentiodynamic polarization) and gravimetric methods are applied to study the corrosion of Csteel with PVP over a range of concentrations and temperatures. The polarization method indicates that PVP behaves as a mixed-type inhibitor. The impedance method reveals that the charge transfer process is dominant in controlling the corrosion of C-steel. The inhibition efficiencies ranged from 56–83%, as determined by weight loss, and from 60–90%, as determined by electrochemical methods. The different techniques used confirm the adsorption of PVP on the C-steel surface and consequently the inhibition of the corrosion process. The adsorption of PVP on the C-steel surface is found to obey the Langmuir adsorption isotherm. A mechanism is proposed to explain the inhibitory action of PVP. The...
Journal of Applied Electrochemistry, 1995
The synergistic action caused by iodide ions on the corrosion inhibition of mild steel in 0.5 M H2SO 4 in the presence of dicyclohexylamine (DCHA) has been investigated using potentiodynamic polarization, linear polarization and a.c. impedance techniques. DCHA inhibits the corrosion of mild steel in 0.5M H2SO 4 even at lower concentrations. The inhibition efficiency decreases with increase in the concentration of the amine. The addition of iodide ions enhances the inhibition efficiency to a considerable extent. The adsorption of this compound is also found to obey Langmuir's adsorption isotherm, thereby indicating that the main process of inhibition is by adsorption. The increase in surface coverage values in the presence of iodide ions indicates that DCHA forms an insoluble complex at lower amine concentrations by undergoing a joint adsorption. The synergism parameter (S) is defined and calculated both from inhibition efficiency and surface coverage values. This parameter in the case of DCHA is found to be more than unity, indicating that the enhanced inhibition efficiency caused by the addition of iodide ions is only due to synergism and there is a definite contribution from the inhibitor molecule. Thus, DCHA is then adsorbed by coulombic attraction on the metal surface where the I-is already chemisorbed and thus reduces the corrosion rate.
International journal of electrochemical science
The corrosion inhibition of carbon steel (CS) using the "green" inhibitor, polyvinyl pyrrolidone (PVP) was investigated. This study was conducted at pH 7 and pH 8 in an aerated medium containing 0.1 M NaCl. The effects caused by some additives (KI and untreated clay) were investigated. The study was done over a range of concentrations, temperatures and times. Gravimetric method and electrochemical methods (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation) were applied. The adsorption of PVP led to the formation of a protective film on the metal/solution interface and an increase in the thickness of the electronic double layer as revealed by EIS results. Tafel results indicated that PVP is a mixed-type inhibitor, affecting the iron dissolution and the cathodic reaction as well. The addition of KI to PVP and NaCl-containing solutions significantly increased the inhibition efficiency, while the addition of UC reduced the inhibition efficiency. The adsorption mechanism was fitted with a Langmuir isotherm. The kinetic and thermodynamic parameters (E * app , K, ΔGº ads , ΔHº and ΔSº) were evaluated. The thermodynamic parameters support the % IE results of WL, EIS, and Tafel indicating that PVP is a good corrosion inhibitor for CS in solutions containing NaCl at pH7 and pH8. The addition of KI additives improves the % IE of PVP especially at pH8.
The Open Corrosion Journal, 2009
The effect of iodide ions on the corrosion inhibition of aluminium in 2M HCl in the presence of polyvinylpyrollidone (PVP) was studied using gasometric (hydrogen evolution) technique at 30-60 o C. Results obtained showed that PVP effectively reduces the corrosion rates of aluminium in the acid medium. Inhibition efficiency (%I) increases with increase in concentration of PVP. Increase in temperature increases corrosion rate but decreases inhibition efficiency. The addition of iodide ions enhanced the inhibition efficiency of PVP considerably. Adsorption of PVP and PVP + KI followed Temkin adsorption isotherm. Phenomenon of physical adsorption is proposed from the obtained E a and G ads o values. The synergistic parameter (S 1 ) obtained was found to be greater than unity, which indicates that the enhanced inhibition efficiency caused by the addition of iodide is only due to synergistic effect.
Anti-Corrosion Methods and Materials, 2013
The corrosion inhibition of carbon steel (CS) using the "green" inhibitor, polyvinyl pyrrolidone (PVP) was investigated. This study was conducted at pH 7 and pH 8 in an aerated medium containing 0.1 M NaCl. The effects caused by some additives (KI and untreated clay) were investigated. The study was done over a range of concentrations, temperatures and times. Gravimetric method and electrochemical methods (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation) were applied. The adsorption of PVP led to the formation of a protective film on the metal/solution interface and an increase in the thickness of the electronic double layer as revealed by EIS results. Tafel results indicated that PVP is a mixed-type inhibitor, affecting the iron dissolution and the cathodic reaction as well. The addition of KI to PVP and NaCl-containing solutions significantly increased the inhibition efficiency, while the addition of UC reduced the inhibition efficiency. The adsorption mechanism was fitted with a Langmuir isotherm. The kinetic and thermodynamic parameters (E * app , K, ΔGº ads , ΔHº and ΔSº) were evaluated. The thermodynamic parameters support the % IE results of WL, EIS, and Tafel indicating that PVP is a good corrosion inhibitor for CS in solutions containing NaCl at pH7 and pH8. The addition of KI additives improves the % IE of PVP especially at pH8.
Synergistic Inhibition Between Polyvinylpyrollidone and Iodide Ions on Corrosion of Aluminium in HCl
The effect of iodide ions on the corrosion inhibition of aluminium in 2M HCl in the presence of polyvinylpyrollidone (PVP) was studied using gasometric (hydrogen evolution) technique at 30-60 o C. Results obtained showed that PVP effectively reduces the corrosion rates of aluminium in the acid medium. Inhibition efficiency (%I) increases with increase in concentration of PVP. Increase in temperature increases corrosion rate but decreases inhibition efficiency. The addition of iodide ions enhanced the inhibition efficiency of PVP considerably. Adsorption of PVP and PVP + KI followed Temkin adsorption isotherm. Phenomenon of physical adsorption is proposed from the obtained E a and G ads o values. The synergistic parameter (S 1 ) obtained was found to be greater than unity, which indicates that the enhanced inhibition efficiency caused by the addition of iodide is only due to synergistic effect.
Corrosion inhibition and adsorption behaviour for pure iron in 0.5 M H 2 SO 4 by polyacrylamide (PA) were investigated using electrochemical techniques. The effect of iodide ion additives was also studied. It was found that inhibition efficiency increased with PA concentration. Corrosion inhibition was afforded by adsorption of PA onto the metal following El-Awady kinetic-thermodynamic adsorption isotherm model via chemisorption mechanism. A mixed inhibition mechanism is proposed for the inhibitive effects of PA as revealed by potentiodynamic polarization technique. A synergistic effect was observed between PA and KI as evident from the values of synergism parameter found to be greater than unity.