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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.

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.

Results obtained show that inhibition efficiency (η%) 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.

The mechanistic aspect of the corrosion inhibition can be better understood using electrochemical studies such as potentiodynamic polarization and electrochemical impedance spectroscopy.

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.

The purpose of this paper is to evaluate the performance of polypropylene glycol (PPG), as a corrosion inhibitor for aluminium corrosion in 0.5 M H₂SO₄ solution at 303-333 K and the effect of addition of iodide ions on the corrosion inhibition efficacy of PPG.

The corrosion inhibition performance of PPG alone and on addition of iodide ions in the acid medium was evaluated using weight loss and electrochemical [electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR) and potentiodynamic polarization (PDP)] methods as well as surface analysis approach at 303-333 K. The morphology of the corroding aluminium surface without and with the additives was visualised using scanning electron microscopy (SEM). The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption.

Results obtained showed that PPG moderately retarded the corrosion of Al in 0.5 M H₂SO₄ solution. Addition of KI to PPG is found to synergistically improve the inhibitive ability of PPG. From the variation of inhibition efficiency, K_ads, and E_a, with rise in temperature, physisorption mechanism is proposed for the adsorption of PPG and PPG + KI onto the Al surface in 0.5 M H₂SO₄ solution. Polarisation results showed that PPG and PPG + KI acted as mixed type inhibitor. The adsorption of PPG and PPG + KI, respectively, onto the metal surface followed El-Awady et al. adsorption isotherm model. SEM and water contact angle analysis confirmed the adsorption of PPG and PPG + KI on Al surface.

The research is limited to aqueous acid environment in aerated condition, and all tests were performed under static conditions.

The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal.

The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal.

The purpose of this paper is to investigate the effect of Raphia hookeri exudate gum and halide ions on the corrosion inhibition of aluminium in HCl solutions at 30‐60°C and to study the mechanism of action.

The corrosion rates were determined using the gravimetric (weight loss), gasometric (hydrogen evolution) and thermometric techniques. The results obtained in the absence and presence of Raphia hookeri, halides and Raphia hookeri – halides combination were used to calculate the inhibition efficiency (%I), degree of surface coverage and to propose the mechanism of inhibition and type of adsorption.

Results obtained showed that the Raphia hookeri exudates gum acted as an inhibitor for aluminium corrosion in acidic environment. Inhibition efficiency (%I) increased with increase in concentration of the Raphia hookeri exudates gum and synergistically increased to a considerable extent on the addition of halide ions. The increase in inhibition efficiency (%I) and surface coverage (θ) in the presence of the halides was found to be in the order I⁻ > Br⁻ > Cl⁻ which indicates that the radii as well as electronegativity of the halide ions play a significant role in the adsorption process. Raphia hookeri exudates gum obeys Freundlich, Langmuir and Temkin adsorption isotherms. Phenomenon of physical adsorption is proposed from the values of kinetic/thermodynamic parameters obtained. The values of synergism parameter (S_I) obtained for the halides are greater than unity suggesting that the enhanced inhibition efficiency of the Raphia hookeri caused by the addition of the halide ions is only due to synergistic effect.

Electrochemical studies such as polarization and AC impedance spectra will throw more light on the mechanistic aspects of the corrosion inhibition and more exudate gums need to be evaluated as corrosion inhibitors.

Raphia hookeri exudate gum can be used as corrosion inhibitor and the addition of halides to it improves the inhibition efficiency considerably.

This paper provides new information on the use of exudate gums as corrosion inhibitors and addition of halides in acidic medium. This environmentally friendly inhibitor could find possible applications in metal surface anodizing and surface coatings.

To investigate the adsorption behaviour and inhibitive effect of Vigna unguiculata (VU) extract (agricultural waste material) for aluminium corrosion in 0.5 M NaOH and H₂SO₄.

The inhibitive effect of the plant extract was assessed using weight loss method at 30 and 60^oC. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption.

VU extract effectively inhibited aluminium corrosion in both alkaline and acidic media. Inhibition efficiency (I %) of the extract increased with increase in concentration of the extract and temperature. Inhibitor adsorption characteristics were approximated by Freunlich and Temkin adsorption isotherms at all the concentrations and temperatures studied. The phenomenon of chemical adsorption is proposed from the activation parameters obtained.

The mechanistic aspect of the corrosion inhibition can be better understood using electrochemical studies such as polarization and AC impedance spectra.

The findings may be useful in metal surface anodizing and metal coating.

This paper provides new information on the possible application of VU extract as eco‐friendly inhibitor. It has not been reported elsewhere.

The aim of this paper is to appraise the inhibiting potential of hydroxypropyl methylcellulose (HPMC) on the corrosion of mild steel and aluminium in sulphuric and hydrochloric acid solutions.

The effects of two different corrodents on the dissolution of mild steel and aluminium were examined. Corrosion rates were determined using the weight loss technique. Inhibition efficiency was estimated by comparing the corrosion rates in absence and presence of the additive. The kinetics and mechanism of HPMC adsorption were investigated by impedance study while the anodic and cathodic partial reactions were studied by polarization measurements.

The results reveal that corrosion rate of mild steel and aluminium decreased with addition of HPMC. The corrosion rate and inhibition efficiency were found to depend on the concentration of the inhibitor. The polarization data indicated that the inhibitor was of mixed-type, with predominant effect on the cathodic partial reaction. electrochemical impedance spectroscopy confirms that corrosion inhibition was by adsorption on the metal surface following Freundlich adsorption isotherm via physisorption mechanism.

Hydroxypropyl methylcellulose has been studied for the first time as an inhibitor of mild steel and aluminium corrosion and the results suggest that the inhibitor could find practical applications in corrosion control in HCl and H₂SO₄ acid media. The findings are particularly useful, considering the fact that HPMC is a good film former and viscosity enhancer which could also be used in paint formulation.

This paper aims to investigate the influence of temperature (25-65°C) on the adsorption and the inhibition efficiency of gum arabic (GA) for the corrosion of API 5L X42 pipeline steel in 1M HCl.

Inhibition behaviour on steel in HCl has been studied in relation to the concentration of the inhibitor and the temperature using potentiodynamic polarization curves and electrochemical impedance spectroscopy. Thermodynamic parameters of adsorption were calculated from the viewpoint of adsorption theory.

The results show that at a temperature range from 25 to 65°C, GA was a good inhibitor for API 5L X42 pipeline steel, and its inhibition efficiency was significantly stable. The maximum inhibition efficiency (93 per cent) is obtained at 4 g L⁻¹. In absence and presence of GA, there is almost no change in the corrosion mechanism regardless of the temperature. The adsorption of GA on steel surface is an exothermic process. The adsorption of GA involves physical adsorption.

The use of GA as an eco-friendly corrosion inhibitor is practical for carbon steel in HCl.

The stability of inhibition efficiency of GA at a temperature range from 25 to 65°C could find possible applications in acid pickling, industrial acid cleaning and acid descaling.

Electrochemical measurements were used to characterize the inhibiting effectiveness of Curcuma and saffron, considered as green inhibitors in a corrosive environment 3% NaCl on A106 Gr B carbon steel.

This study/paper aims to polarization and potentiodynamic impedance spectroscopy techniques were performed on A106 Gr B carbon steel in the 3% NaCl environment only and containing various concentrations of Curcuma and Saffron (0.005, 0.01, 0.02, 0.04, g/L) after 30 min of immersion; these measures were taken at a temperature of (298 ± 1)K. A voltlab PGZ 301 assembled by A 106 Gr B carbon steel working electrode, a platinum counter electrode (CE) and a saturated calomel electrode as the reference electrode were used in the experiment. In this research, potentiodynamic polarization and electrochemical impedance spectroscopy were used.

The inhibition efficiencies increased with increase in the concentrations of the inhibitor but decreased with rise in temperature. The obtained results show an optimal efficiency with 0.04 g/L which are ordered of 78 and 96 per cent successively for the two inhibitors. Curcuma and saffron acts as a mixed type inhibitor. Adsorption of the inhibitor molecules corresponds to Langmuir adsorption isotherm. Mechanism of inhibition was also investigated by calculating the thermodynamic and activation parameters like (ΔG), (E_a), (ΔH_a) and (ΔS_a). The inhibitor molecules followed physical adsorption on the surface of carbon steel.

The present trend in research on environmental friendly corrosion inhibitors is concentrating on products of natural origin due principally to non-toxicity and eco-friendliness. Among these natural products are curcuma and saffron.

To investigate the effect of halide ions on the corrosion inhibition of mild steel using polyvinyl alcohol (PVA) in H₂SO₄ at 30‐60°C and to study the mechanism of action.

The corrosion rates were determined using the gravimetric (weight loss) and gasometric (hydrogen evolution) techniques. The results obtained in the absence and presence of PVA, halides, PVA – halides combination were used to calculate the inhibition efficiency (%I), degree of surface coverage and to propose the mechanism of inhibition and type of adsorption.

Results obtained showed that inhibition efficiency (%I) increased with the increase in concentration of PVA, on the addition of halides and with the increase in temperature. Phenomenon of chemical adsorption was proposed and PVA was found to obey Langmuir, Flory‐Huggins and Freundlich adsorption isotherms. The synergism parameter, S₁, evaluated was found to be greater than unity and the values of E_a, ΔH°, ΔS° and ΔG° obtained revealed that the adsorption process was spontaneous.

Electrochemical studies such as polarization and AC impedance spectra will enlighten more on the mechanistic aspects of the corrosion inhibition and more polymers need to be evaluated as corrosion inhibitors.

PVA can be used as corrosion inhibitor and the addition of halides to PVA improves the inhibition efficiency considerably.

This paper provides new information on the effects of halides on the corrosion inhibition using PVA as an inhibitor for mild steel in acidic medium. Such a study had not been reported elsewhere.

The purpose of this paper is to study the corrosion inhibition of carbon steel (CS) using a “green” inhibitor, polyvinyl pyrrolidone (PVP), in an aerated, alkaline medium containing 0.1M NaCl (blank) at pH 9 and pH 10. The effects of some additives, such as KI and untreated Saudi clay (UC) were investigated.

Weight loss method, surface studies, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation were applied.

The inhibition efficiencies of blank solutions with 1000 ppm PVP ranged from 66‐78% for weight loss results and from 23‐66% for the electrochemical tests. The EIS results indicated that the adsorption of PVP led to the formation of a protective film on the metal/solution interface. Tafel results indicated that PVP is a mixed‐type inhibitor. The addition of KI to PVP and the blank solution significantly increased inhibition efficiency, while the addition of UC reduced the inhibition efficiency. Adding KI resulted in a high surface‐area coverage ranging from about 91% after one hour to about 81% after 45 hours. The adsorption mechanism was fitted with a Langmuir isotherm.

This is a static study, whereas in oil drilling there is a dynamic system; however the findings may apply to both systems.

Carbon steel is used in alkaline and neutral media in the petroleum industry. The effect of KI additives was examined.

The paper shows how it may be possible to reduce the cost of repair of equipment and lower the environmental impact of corrosion.

There are few studies which investigate the combining effect of polymer and KI in alkaline medium containing NaCl.

The aim of this paper is to investigate peach juice as a cheap, raw, green and non‐toxic anti‐corrosion material for mild steel corrosion in hydrochloric acid at different temperatures.

The corrosion inhibition of mild steel in 1 M HCl solution in the presence of peach juice at temperature range of 30‐60°C and concentration range of 5‐50 cm³/l was studied using weight loss and polarization techniques. The inhibition effect, adsorption characteristics, mathematical and electrochemical modeling of peach juice were addressed.

Results show that inhibition efficiency rose with the increase of inhibitor concentration and temperature up to 50°C, while at temperatures above 50°C the values of efficiency decreased. The inhibitor adsorbed physically on metal surface and followed the Langmuir adsorption isotherm. Monolayer formed spontaneously on the metal surface. Maximum inhibition efficiency obtained was about 91 percent at 50°C in the 50 cm³/l inhibitor concentration.

This work is an attempt to find a new, safe to environment, non‐toxic corrosion inhibitor. Peach juice is a readily available material in Iraq and Middle East markets.