Synergistic Inhibition Between Polyvinylpyrollidone and Iodide Ions on Corrosion of Aluminium in HCl (original) (raw)
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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.
The corrosion and inhibition behaviour of aluminium in hydrochloric acid (HCl) in the absence and presence of polyvinyl pyrrolidone (PVP), Polyacrylamide (PA) and their blends was studied in the temperature range of 30 -60 o C using weight loss, hydrogen evolution and thermometric techniques. The inhibition efficiency (%I) increased with increase in inhibitors concentration. Increased in temperature led to increase in corrosion rate but decreased the inhibition efficiency PVP was found to have the higher inhibition efficiency than PA which may suggest that the differences in their molecular structures play a significant role in the adsorption and hence inhibition process. Inhibition efficiency was enhanced on blending the two polymers; the optimum inhibition efficiency was obtained at 3:1 blending ratio for PVP: PA. The inhibitors (PVP and PA) obey Freundlich, Temkin and Flory-Huggins adsorption isotherms at all the temperatures. Results obtained from the kinetic and thermodynamic parameters indicate spontaneous adsorption of the inhibitors unto aluminium surface following physical adsorption mechanism.
Journal of Applied Polymer Science, 2006
The corrosion inhibition of aluminum in H2SO4 in the presence of polyvinyl alcohol (PVA) and polyethylene glycol (PEG) and the effect of addition of halides (KCl, KBr, KI) was studied using the hydrogen evolution technique at 30 and 40°C. Inhibition efficiency (%I) increases with concentration of PVA and PEG—-but with PEG having higher %I. The %I decrease with increase in temperature from 30 to 40°C in the absence and presence of inhibitor and halides. PVA and PEG were found to obey Freundlish adsorption isotherm. Phenomenon of physical adsorption is proposed from the obtained Ea, ΔGads, and Qads values obtained. The synergism parameters (SI) obtained were found to be greater than unity for both PVA and PEG, which indicates that the enhanced inhibition efficiency caused by the addition of halides is only due to synergism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2889–2894, 2006
The performance of PVAc as a safe inhibitor for corrosion of aluminium in 2 M H2SO4 and 0.5 M HCl solution at varying temperatures was investigated by weight loss, polarization measurement and computational technique. Weight loss measurements showed that PVAc exhibited excellent inhibitory character within the studied environment and efficiency of inhibition increased with increasing concentration of PVAc, but decreased with rise in temperature. Also, it is observed that aluminium displayed higher susceptibility to dissolution in the hydrochloric compared to sulphuric acid. Results of free energy of adsorption suggest physical adsorption. The adsorption of PVAc on the aluminium surface followed Langmuir adsorption isotherm, thus showing evidence of physisorption mechanism. Polarization results revealed that PVAc functions as a mixed-type inhibitor with absolute control of the anodic reaction. Results of computational technique showed the apparent correlation between corrosion inhibition efficiency and electronic molecular structure regarding frontier molecular orbital theory.
Polyethylene glycol and polyvinyl alcohol as corrosion inhibitors for aluminium in acidic medium
Journal of Applied Polymer Science, 2007
The corrosion inhibition of aluminum in H 2 SO 4 in the presence of polyethylene glycol (PEG) and polyvinyl alcohol (PVA) as inhibitors at 30-60 8C was studied using gravimetric, gasometric, and thermometric techniques. The inhibition efficiency (%I) increased with increase in concentration of the inhibitors. Increase in temperature increased the corrosion rate in the absence and presence of inhibitors but decreased the inhibition efficiency. Both PEG and PVA were found to obey Temkin adsorption isotherm at all concentrations and temperatures studied. Phenomenon of physical adsorption is proposed from the activation parameters obtained. Thermodynamic parameters reveal that the adsorption process is spontaneous. PEG was found to be a better inhibitor than PVA.
The corrosion inhibition of Al in 0.5 M H2SO4 solution by poly (methacrylic acid) (PMAA) alone and in combination with iodide ions was studied at 303–333 K using gravimetric, electrochemical impedance spectroscopy, potentiodynamic polarization, scanning electron microscopy and water contact angle measurements techniques. Results obtained show that PMAA moderately inhibited the dissolution of Al in the corrosive medium. Addition of Iodide ions synergistically upgrades the inhibition efficiency of PMAA to a maximum value of 82.6%. From polarization results, PMAA and PMAA + KI can be classified as mixed-type corrosion inhibitor. Thermodynamic parameters namely Gibbs free energy of adsorption, activation energy and enthalpy of activation revealed that the adsorption processes of PMAA and PMAA + KI are endothermic reactions mainly by a physisorption mechanism and followed El-Awady et al. thermodynamic–kinetic adsorption isotherm.
Purpose – The purpose of this paper is to investigate the effect of polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) and blended formulations on the corrosion inhibition of aluminium in HCl solutions at 30-60°C and to study the mechanism of action. Design/methodology/approach – The inhibitive effect of the homopolymers and polymer blend was assessed using weight loss and hydrogen evolution methods at 30 and 60°C. The morphology of the corroding aluminium surface without and with the additives was visualized using atomic force microscopy. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption. Findings – Results obtained show that inhibition efficiency (%) increases with increase in concentration of the polymers but decreases with increase in temperature. The inhibition efficiency of the homopolymers and their blends decreased with rise in temperature. Inhibition efficiency was found to be synergistically enhanced on blending the two homopolymers with highest inhibition efficiency obtained for (PEG:PVP) blending ratio of 1:3. The phenomenon of physical adsorption is proposed from the trend of inhibition efficiency with temperature. Research limitations/implications – The mechanistic aspect of the corrosion inhibition can be better understood using electrochemical studies such as potentiodynamic polarization and electrochemical impedance spectroscopy. Originality/value – Studies involving the use of polymer blends/mixtures as corrosion inhibitor for metals in corrosive environments are scarce. The results suggest that the mixture could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the use of polymer–polymer mixtures to control acid-induced corrosion of metal.
Journal of Applied Polymer Science, 2009
The corrosion inhibition of aluminium in alkaline medium was studied at 30 and 40°C in the presence of polyethylene glycol (PEG) using gravimetric (weight loss) and thermometric techniques. The effect of halides (KCl, KBr, and KI) on the inhibitory action of PEG was also studied. It was found that PEG acted as inhibitor for aluminium corrosion in the alkaline medium. Inhibition efficiency increased with increasing inhibitor concentration. An increase in temperature led to increase in both the corrosion rate and inhibition efficiency in the absence and presence of inhibitor and halides. Phenomenon of chemical adsorption mechanism is proposed from the values of Ea, Qads, and ΔG obtained. The adsorption of PEG on the surface of aluminium was found to obey Flory–Huggins and Temkin adsorption isotherms. The synergism parameter, S1 evaluated was found to be greater than unity indicating that the enhanced inhibition efficiency caused by the addition of halides is synergistic in nature. The inhibition efficiency, surface coverage and synergism parameter increased in the order; I−> Br−> Cl− showing that a joint adsorption of PEG and halide ions on aluminium plays a significant role in the adsorption process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Inhibition of Corrosion of Aluminium in Alkaline Medium by Poly(Vinyl Alcohol) (Pva)
2014
The inhibition efficiency of polyvinylalcohol (PVA) in controlling corrosion of aluminium in well water in the absence and presence of Zn 2+ has beenevaluated by weight loss method. The formulation consisting of 250 ppm of PVA and 25 ppm of Zn 2+ offers 85 % inhibition efficiency. It is found that the inhibition efficiency of PVA increases by addition of Zn 2+ ion. A synergistic effect exists between PVA and Zn 2+. The mechanistic aspects of corrosion inhibition have been studied using polarization study. Also FTIR spectra reveal that the protective film consists of PVA - Zn 2+ complex and Zn(OH) 2 . The scanning electron microscopy confirms the protection of aluminium surface by strong adsorption of PVA. A suitable mechanism for corrosion inhibition is proposed based on the results from the above studies.
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.