O.K. Abiola, N.C. Oforka, E.E. Ebenso and N.M. Nwinuka
To investigate the inhibitive effect of Delonix regia extracts to reduce the corrosion rate of aluminium in acidic media. The study was a trial to find a low cost and…
Abstract
Purpose
To investigate the inhibitive effect of Delonix regia extracts to reduce the corrosion rate of aluminium in acidic media. The study was a trial to find a low cost and environmentally safe inhibitor to reduce the corrosion rate of aluminium.
Design/methodology/approach
The inhibition efficiency was evaluated using the hydrogen evolution technique at 30°C. The mechanism of adsorption inhibition and type of adsorption isotherm was characterised from trends of inhibition efficiency and kinetic data.
Findings
Delonix regia extracts inhibited the corrosion of aluminium in hydrochloric acid solutions. The inhibition efficiency increased with increasing concentration of the inhibitor but decreased with increase in exposure time. The acid extracts (hydrochloric acid seeds extract (HSE) and hydrochloric acid leaf extract (HLE)) were found to be more effective than the ethanolic extracts (ethanol seeds extract (ASE) and ethanol leaves extract (ALE)) and the inhibition followed the order: HSE (93.6 per cent) > HLE (83.5 per cent) > ASE (63.9 per cent) > ALE (60.4 per cent). The low negative values of ΔGad: −20.14 kJ mol−1 for HSE, −18.08 kJ mol−1 for HLE, −15.96 kJ mol−1 for ASE and −15.12 kJ mol−1 for ALE, as calculated from the Langmuir isotherm, indicated that the inhibitor molecules adsorbed onto aluminium by a physiosorption‐based mechanism. A first‐order type of reaction mechanism was obtained from the kinetic treatment of the H2 gas evolution data.
Research limitations/implications
Further investigations involving electrochemical studies such as polarization method should shed further light on the mechanistic aspects of the corrosion inhibition.
Originality/value
This paper provides new information on the possible application of Delonix regia as an environmentally friendly corrosion inhibitor under the specified conditions. This environmentally friendly inhibitor could find possible applications in metal surface anodizing and surface coatings.
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Fatima Bensajjay, Saliha Alehyen, Mohammed El Achouri, Najat Hajjaji, Abdelkbir Bellaouchou, Lourdes Perez and Maria Rosa Infante
The purpose of this investigation is the evaluation of the inhibitive performance of a new “gemini” surfactant in the series of bis‐quat: N, N, N′, N″, N″‐pentamethyl…
Abstract
Purpose
The purpose of this investigation is the evaluation of the inhibitive performance of a new “gemini” surfactant in the series of bis‐quat: N, N, N′, N″, N″‐pentamethyl diethyleneamine‐N, N″‐di‐[tetradecylammonium bromide] on the corrosion of iron in 1 M HCl by gravimetric, potentiodynamic and electrochemical impedance measurements. The effect of the temperature on the corrosion behavior of iron in 1 M HCl without and with inhibitor is studied in the temperature range (298‐333 K). This work also attempts to correlate thermodynamic and kinetic parameters with the inhibition effect.
Design/methodology/approach
The inhibition efficiency of gemini synthesized is investigated by weight loss, potentiodynamic polarization and impedance spectroscopy methods.
Findings
The synthesized gemini bis‐quat acted as a good inhibitor in 1 M HCl, and inhibition efficiency increased with inhibitor concentration and temperature. Polarization curves showed that the surfactant was a mixed‐type inhibitor in hydrochloric acid. Impedance spectroscopy measurements showed that the inhibitor acted through the formation of a multilayer film at the iron surface. The adsorption of inhibitor on the iron surface obeyed the Langmuir adsorption isotherm equation. The inhibition effect was satisfactorily explained by both thermodynamic and kinetic parameters.
Originality/value
The adsorption of surfactants in the metal surface can markedly change the corrosion resisting property of the metal. So the study of the relation between the adsorption and corrosion inhibition is of a great importance. This was the first attempt to study the inhibition properties of gemini surfactants at the host laboratory.
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Sadaf Khan, M.Z.A. Rafiquee, Nidhi Saxena and M.A. Quraishi
The purpose of this paper is to investigate the inhibitive effect of azathiones, namely cyclopentyl‐tetrahydro‐azathione, cyclohexyl‐tetrahydro‐azathione and…
Abstract
Purpose
The purpose of this paper is to investigate the inhibitive effect of azathiones, namely cyclopentyl‐tetrahydro‐azathione, cyclohexyl‐tetrahydro‐azathione and isobutyl‐methyl‐tetrahydro‐azathione on the corrosion of carbon steel in formic and acetic acid solution. The effect of inhibitor concentration, immersion time, acid concentration, and solution temperature on the inhibition efficiencies of the selected azathiones were studied systematically.
Design/methodology/approach
The synthesis of inhibitor was confirmed by methods such as Fourier transform infrared and nuclear magnetic resonance studies. All inhibition experiments were conducted on carbon steel in 20 percent formic acid and 20 percent acetic acid solution. Weight loss experiments were carried out according to the American Society for Testing and Materials standard procedure. Polarization studies were carried out in a three electrode cell assembly connected to an EG&G Princeton Applied Research potentiostat/galvanostat (model 173). The electrochemical impedance technique was carried out using Zahner IM‐6 electrochemical workstation at a frequency range of 5‐100 Hz. The scanning electron microscopy (SEM) study was carried out using a VP LEO model no. 435 microscope for the surface characterization of inhibited and uninhibited metal surfaces.
Findings
Various thermodynamic parameters were calculated using weight loss data in order to elaborate the mechanism of corrosion inhibition. Polarization measurements revealed that the studied azathiones acted predominantly as mixed inhibitors. Electrochemical impedance measurements revealed that the compounds were adsorbed onto the carbon steel surface and the adsorption obeyed the Langmuir adsorption isotherm. The SEM study showed that the inhibited metal surfaces were smoother than were uninhibited metal surfaces.
Research limitations/implications
The presence of high efficiency and low cost inhibitors is essential for protection of carbon steel. In comparison with conventional carbon steel corrosion inhibitors, these findings would be considered as a step forward in development of new corrosion inhibitor.
Originality/value
This paper reveals that azathiones can be used successfully for the protection of carbon steel surfaces exposed in acid solution.
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The purpose of this paper was to test the extract of barley as an environmentally friendly inhibitor for the acid corrosion of steel due to its wide availability as a popular…
Abstract
Purpose
The purpose of this paper was to test the extract of barley as an environmentally friendly inhibitor for the acid corrosion of steel due to its wide availability as a popular major crop and its richness with different chemical constituents reported in literature (40) like alanine, glycine, serine, aspartic acid, leucine, valine, tyrosine and isoleucine with various number of functional groups that are able to chelate metal cations and to discuss the effect of temperature on its inhibition efficiency.
Design/methodology/approach
Electrochemical impedance spectroscopy (EIS) and polarization measurements were carried out using frequency response analyzer Gill AC instrument. The frequency range for EIS measurements was 0.1 ≤ f ≤ 1 × 103 with an applied potential signal amplitude of 10 mV around the rest potential. Polarization measurements were carried out at a scan rate of 30 mV/min, utilizing a three-electrode cell. A platinum sheet and saturated calomel electrode were used as counter and reference electrodes, respectively. The working electrode was constructed with steel specimens that have the following composition (weight per cent): C, 0.21; S, 0.04; Mn, 2.5; P, 0.04; Si, 0.35; and balance Fe.
Findings
Barley extract could act as an effective corrosion inhibitor for the acid corrosion of steel. The inhibiting action of the barley extract was attributed to its adsorption over the metal surface that blocks the available cathodic and anodic sites. Adsorption isotherms indicated that the adsorbed extract molecules cover one active center over the metal surface.
Originality/value
The research included the first use of an important world crop as an effective corrosion inhibitor that can reduce the corrosion of steel to an extent of 94 per cent.
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Alexander I. Ikeuba and Peter C. Okafor
This paper aims to appraise the inhibitory effect of saponins extracted from Gongronema latifolium (SEGL) on mild steel in acid media. This is in a bid to conserve our environment…
Abstract
Purpose
This paper aims to appraise the inhibitory effect of saponins extracted from Gongronema latifolium (SEGL) on mild steel in acid media. This is in a bid to conserve our environment and maintain the integrity of engineering structures and materials.
Design/methodology/approach
The corrosion inhibition of SEGL and ethanolic extracts of the leaves of G. latifolium (EEGL) on mild steel was studied by hydrogen evolution technique within a temperature range of 30-60°C in tetraoxosulphate (VI) acid solutions.
Findings
The extracts inhibit the corrosion of mild steel, and the inhibition efficiency depends on the concentration of the plant extract, temperature and the period of immersion. SEGL was comparatively more efficient than EEGL. Optimum values of the inhibition efficiency for both the EEGL and SEGL (93.7 and 96.5 per cent, respectively) were obtained at extract concentration of 10 g/L, whereas the least values were obtained at extract concentration of 0.5 g/L.
Originality/value
This paper provides new information on the possible application of isolated SEGL as an environmentally friendly corrosion inhibitor. The possible mechanism of the inhibitive action is also given.
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Z. Faska, L. Majidi, R. Fihi, A. Bouyanzer and B. Hammouti
This paper seeks to evaluate the effect of natural menthols and their synthesised epoxy‐allylmenthols as a non‐toxic inhibitor on the corrosion of steel in HCl media at various…
Abstract
Purpose
This paper seeks to evaluate the effect of natural menthols and their synthesised epoxy‐allylmenthols as a non‐toxic inhibitor on the corrosion of steel in HCl media at various temperatures.
Design/methodology/approach
Epoxy‐allylmenthols were synthesised and characterised. Gravimetric technique was used to measure the efficiency of corrosion inhibition.
Findings
Modified allylmenthol (to epoxy‐allylmenthol) exhibited a good inhibition. But its efficiency decreases with temperature.
Research limitations/implications
The inhibition efficiency increases with the concentration of inhibitor to attain 74 percent at 0.8 g/l.
Practical implications
The efficiency of menthol derivatives increases with the concentration but decreases with rise of temperature in the 303‐328 K range. Natural inhibitor can be used in chemical cleaning and pickling processes.
Originality/value
The originality of this work is to find a safe and cheap eco‐friendly inhibitor from natural plants.
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P.C. Okafor, V.I. Osabor and E.E. Ebenso
This paper aims to investigate the inhibitive effect of ethanol extracts of Garcinia kola (EXG) for the corrosion of mild steel in H2SO4 solutions. The study is another trial to…
Abstract
Purpose
This paper aims to investigate the inhibitive effect of ethanol extracts of Garcinia kola (EXG) for the corrosion of mild steel in H2SO4 solutions. The study is another trial to find a cheap and environmentally safe inhibitor for mild steel corrosion.
Design/methodology/approach
The inhibition efficiency has been evaluated using the hydrogen evolution technique at 30‐60°C. The mechanism of adsorption inhibition and type of adsorption isotherm were proposed based on the trend of inhibition efficiency and kinetic data.
Findings
The results obtained indicate that EXG inhibits the corrosion of mild steel in acidic medium and that the inhibition efficiency increases with an increase in the concentration of ethanol extracts and decreasing temperature. The inhibition efficiency increased on addition of potassium iodide to EXG, indicating synergism. The experimental data obeyed the Langmuir adsorption isotherm as well as the El‐Awady et al. thermodynamic‐kinetic model. The activation energy of inhibition of 6.8508 KJ/mol calculated for the corrosion process suggests that the EXG molecules are physically adsorbed on the metal surface.
Research limitations/implications
Further investigations involving electrochemical studies such as polarization method will provide further enlightenment on the mechanistic aspect of the corrosion inhibition.
Originality/value
This paper provides new information on the possible application of EXG as an environmentally friendly corrosion inhibitor under the specified conditions. This environmentally friendly inhibitor could find possible applications in metal surface anodizing and surface coatings.
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The purpose of this paper is to make people aware of organic corrosion inhibitors.
Abstract
Purpose
The purpose of this paper is to make people aware of organic corrosion inhibitors.
Design/methodology/approach
As it is a literature review paper, no specific method is used.
Findings
It has been found that plant extracts and oils show inhibition efficiency up to 98 percent, so it is certain that plant extracts and oils are effective corrosion inhibitors and can be successfully used at the industrial level.
Research limitations/implications
Plant extracts and oils are also found to be non‐toxic, highly efficient, renewable and cheap. But less effort has been given towards the identification of which compound is active in the extract.
Originality/value
The paper shows detailed account of the inhibitors obtained from plants, which are used as natural corrosion inhibitors.
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Sang Xiong, Hao Wu and Zhiyuan Liu
N-containing heterocyclic benzotriazole derivatives as new corrosion inhibitor for mild steel contained in emulsion were synthesized, and their inhibition behaviors for mild steel…
Abstract
Purpose
N-containing heterocyclic benzotriazole derivatives as new corrosion inhibitor for mild steel contained in emulsion were synthesized, and their inhibition behaviors for mild steel (MS) contained in emulsion were investigated by experiments and theoretical calculations, and this study aims to prove that two new inhibitors have excellent inhibition efficiency for steel corrosion.
Design/methodology/approach
2-(1H-benzo[d][1,2,3]triazol-1-yl)-N,N-dioctylacetamide (BTN) and O-(3-(1H-benzo[d] [1,2,3]triazol-1-yl)propyl) S-(2-(dioctylamino)-2-oxoethyl) carbonodithioate (BTSC) as a new corrosion inhibitor were synthesized, and their inhibition behaviors for MS contained in emulsion were investigated by gravimetric experiment, electrochemical tests and theoretical calculations.
Findings
Results of gravimetric experiment, electrochemical tests show that BTSC exhibit excellent inhibition performance, and it has a higher inhibition efficiency of 96.6% than that BTN. The resultant adsorption films from BTN/BTSC adsorbed on MS, effectively inhibiting the corrosion of MS is mainly through chemisorption and follow to Langmuir’s adsorption isotherm.
Originality/value
Experimental and theoretical calculations display that two new synthesized inhibitors are excellent corrosion inhibitor for MS contained in emulsion. Electrons of inhibitors mainly focus on the C, N, S and O atoms, which demonstrate these atoms are the centers of negative charge, and they supply electrons to Fe atoms through coordination bonds.
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M. Bendahou, M. Benabdellah and B. Hammouti
To evaluate the effect of natural rosemary oil as non toxic inhibitor on the corrosion of steel in H3PO4 media at various temperatures.
Abstract
Purpose
To evaluate the effect of natural rosemary oil as non toxic inhibitor on the corrosion of steel in H3PO4 media at various temperatures.
Design/methodology/approach
The oil was hydro‐distilled. The oil was used as inhibitor in various corrosion tests. Gravimetric and electrochemical techniques were used to characterise the corrosion mechanism.
Findings
Chromatographic analysis by GC showed that the oil was rich in 1,8‐cineole. The oil was a good inhibitor. But, its efficiency decreased with temperature.
Research limitations/implications
The inhibition efficiency increased with the concentration of the natural oil to attain 73 per cent at 10 g/l. Good agreement between the various methods explored was observed. Polarisation measurements showed that rosemary oil acted essentially as a cathodic inhibitor.
Practical implications
The efficiency of the oil increased with the concentration but decreased with the rise of temperature in the 298‐348 K range. The natural oil could thus be used in chemical cleaning and pickling processes.
Originality/value
The originality of this work is the finding of a safe and cheap inhibitor from natural plants.