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1 – 10 of 90Emeka Oguzie, Chris Akalezi and Conrad Enenebeaku
The purpose of this paper is to study methyl green dye (MG) as a corrosion inhibitor for low carbon steel (LCS) in hydrochloric acid (1 M) and sulphuric acid (0.5 M) and to assess…
Abstract
Purpose
The purpose of this paper is to study methyl green dye (MG) as a corrosion inhibitor for low carbon steel (LCS) in hydrochloric acid (1 M) and sulphuric acid (0.5 M) and to assess the effect of temperature variation and halide additives on the inhibition efficiency.
Design/methodology/approach
Corrosion rates are monitored using the gravimetric technique. Inhibition efficiency is determined by comparing the corrosion rates in the absence and presence of additives. Attempts are also made to elucidate the inhibition mechanism from the trend of inhibition efficiency with change in temperature and type of acid anion.
Findings
MG reduces the corrosion rate of the LCS specimens in both acid media within the investigated temperature range by adsorption at the metal/solution interface. Inhibition efficiency increases with MG concentration but decreases with rise in temperature. Maximum values of 67 and 73 per cent are obtained in 1 M HCl and 0.5 M H2SO4, respectively, at [MG]=0.001 mol dm−3. Halide additives increase the inhibition efficiency mainly in the sulphuric acid medium.
Research limitations/implications
The inhibiting effect of MG is studied within a fixed concentration range, which can be expanded for further studies. The same applies to the effect of halide additives. Also, the dye structure can be modified by introducing different functional groups, and the effect on inhibition efficiency is investigated.
Practical implications
The research findings can find practical application for corrosion control in aqueous acidic environments.
Originality/value
This paper provides new information on the application of MG for corrosion inhibiting purposes. The experimental results form part of an extensive database on the corrosion inhibiting characteristics of organic dyes.
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Chinyere Elizabeth Agiriga, Emeka Oguzie, Arinzechukwu Chidiebere, Nnaemeka John Okorocha and Reginald Ndubuisi Chikwe
This paper aims to investigate the corrosion inhibition efficiency of Landolphia heudelotii (LH) on mild steel in 1 M HCl and 0.5 M H2SO4 using weight loss and potentiodynamic…
Abstract
Purpose
This paper aims to investigate the corrosion inhibition efficiency of Landolphia heudelotii (LH) on mild steel in 1 M HCl and 0.5 M H2SO4 using weight loss and potentiodynamic polarization techniques.
Design/methodology/approach
Water extract of LH was used as corrosion inhibitor on mild steel in acidic media at room temperature and elevated temperatures (30-60°C). Various concentrations of the plant extract were prepared from the stock solution obtained after solvent extraction. The inhibition efficiency of LH extract was evaluated and mechanism of adsorption was deduced.
Findings
LH extract showed significant corrosion inhibition on mild steel in both acidic media, with inhibition efficiency increasing with extract concentration. Potentiodynamic polarization measurements revealed mixed inhibition mechanism. Optimum inhibition efficiency was recorded at 2500 mg/L after 288 h. Mechanism of adsorption was mainly of physisorption. The inhibitor exhibited good inhibition efficiency even at elevated temperature.
Research limitations/implications
This study provides new data on the anticorrosion characteristics of LH extract under the specified conditions. Further studies could expand the experimental variables and use advanced surface probe techniques.
Practical implications
The developed inhibitor provides an alternative method of inhibiting corrosion on mild steel using eco-friendly materials from natural products which are less toxic, safer, cost-effective and readily available.
Originality/value
The method used was effective and the inhibitor developed can be incorporated in surface coatings where mild steel is used as construction materials, as tube sheets, rods and bars.
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To investigate the efficacy of Congo red dye (CR) as an inhibitor of the acid corrosion of mild steel and aluminium alloy (AA 1060) and to assess the influence of halide ions on…
Abstract
Purpose
To investigate the efficacy of Congo red dye (CR) as an inhibitor of the acid corrosion of mild steel and aluminium alloy (AA 1060) and to assess the influence of halide ions on the inhibition efficiency.
Design/methodology/approach
Corrosion rates were estimated by monitoring the weight losses of the metal specimen as a function of time at different temperatures. Inhibition efficiency was determined by comparing the corrosion rates in the acid medium in the absence and presence of the additive.
Findings
CR dye reduced the corrosion rates of mild steel and aluminium in the acidic environment. Better inhibition was observed with the mild steel specimen. Protection efficiency was sensitive to inhibitor concentration as well as temperature and generally increased with an increase in CR dye concentration. The halide additives improved the inhibition efficiency in the order KCl < KBr < KI.
Research limitations/implications
The inhibiting effect of CR dye was studied within a fixed concentration range, which could be expanded for further studies. The same applies to the CR+halide systems. Also, the dye structure could be modified by introducing different functional groups, and the effect on inhibition efficiency investigated.
Practical implications
The research findings could find practical application in corrosion control in aqueous acidic environments.
Originality/value
This paper provides new information on the inhibiting characteristics of CR dye under the specified conditions, as a guide to possible applications in metal surface anodizing and surface coatings.
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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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Originality/value
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.
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E.E. Oguzie, G.N. Onuoha and E.N. Ejike
This paper aims to appraise the effectiveness of Gongronema latifolium extract as an environmentally friendly corrosion inhibitor for aluminium in strong acid (2 M HCl) and…
Abstract
Purpose
This paper aims to appraise the effectiveness of Gongronema latifolium extract as an environmentally friendly corrosion inhibitor for aluminium in strong acid (2 M HCl) and alkaline (2 M KOH) environments.
Design/methodology/approach
Corrosion rates were determined using the gas‐volumetric technique. The efficiency of inhibition was estimated by comparing corrosion rates in absence and presence of the additive, while the mechanism of inhibition was assessed by considering temperature effects on corrosion and inhibition processes.
Findings
The results show that the extract was well adsorbed on the metal surface and significantly repressed aluminium corrosion in both environments. Inhibition efficiency generally increased with concentration up to maximum values of 97.54 and 90.82 per cent in 2 M HCl and 2 M KOH, respectively. Temperature dependence studies revealed that the extract was chemically adsorbed on the aluminium surface at all concentrations in 2 M HCl and physically adsorbed in 2 M KOH, with likely tendency to become chemisorbed at higher concentration.
Originality/value
Gongronema latifolium has been studied for the first time as an inhibitor of aluminium corrosion and the results suggest that the extract could find practical application in corrosion control in aqueous acidic and alkaline environments. The findings are particularly useful, considering the scarcity of reports on the effective inhibition of aluminium corrosion in strong alkaline solutions.
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Innocent Okechi Arukalam, Innocent Chimezie Madufor, Okoro Ogbobe and Emeka E. Oguzie
– The paper aims to investigate the effectiveness of hydroxypropyl methylcellulose (HPMC) as corrosion inhibitor for aluminium in 0.5 M H2SO4 solution.
Abstract
Purpose
The paper aims to investigate the effectiveness of hydroxypropyl methylcellulose (HPMC) as corrosion inhibitor for aluminium in 0.5 M H2SO4 solution.
Design/methodology/approach
This study was carried out using weight loss and electrochemical techniques. Inhibition efficiency was determined by comparing the corrosion rates in the absence and presence of inhibitor system. Quantum chemical computations were performed using density functional theory to assess the parameters responsible for the inhibition process and also to analyse the local reactivity of the molecule.
Findings
HPMC inhibited aluminium corrosion in the acidic environment. The inhibition efficiency was found to depend on concentration of the inhibitor. Impedance results reveal that HPMC is adsorbed on the corroding metal surface. Polarization results show that the dissolution reaction is due to destabilization of the passive oxide film on the Al surface. Adsorption of the inhibitor is approximated by Freundlich adsorption isotherm and the calculated standard free energy of adsorption indicates weak physical interaction between the inhibitor molecules and aluminium surface. This can be attributed to preferential interaction of the active sites with the passive oxide layer. The calculated quantum chemical parameters show good correlation with the inhibition efficiency.
Practical implications
HPMC could find possible application as a polymeric thickener and additive to improve corrosion resistance and barrier properties of anticorrosion paints.
Originality/value
This paper provides novel information on the inhibitive characteristics of HPMC under the stated conditions. The inhibitor systems provide an effective means for suppressing aluminium corrosion even in highly aggressive acidic environments.
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To assess the protective effect and adsorption behaviour of Azadirachta indica extract in controlling mild steel corrosion in 1 M H2SO4 and 2 M HCl.
Abstract
Purpose
To assess the protective effect and adsorption behaviour of Azadirachta indica extract in controlling mild steel corrosion in 1 M H2SO4 and 2 M HCl.
Design/methodology/approach
The inhibitive effect of the plant extract was monitored using the gas‐volumetric technique. The inhibition mechanism was inferred by curve fitting of the experimental data to known adsorption isotherms and the trend of inhibition efficiency with temperature.
Findings
Azadirachta indica extract effectively inhibited steel corrosion in the acid media studied by virtue of adsorption. The inhibitor adsorption characteristics were approximated by Langmuir isotherm. The extract functioned as a mixed inhibitor, depending on its concentration. The prime effect at lower concentration was mitigation of the cathodic reaction by physical adsorption of protonated species in the extract and at higher concentration the anodic reaction was inhibited by chemisorption of molecular species.
Originality/value
This paper provides novel information on the effectiveness of Azadirachta indica extract as a green corrosion inhibitor for steel in highly acidic environments as well as possible mechanisms of the inhibitive action.
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To investigate the efficacy of Telfaria occidentalis extract as a corrosion inhibitor for mild steel in 2 M HCl and 1 M H2SO4 solutions, respectively, and to assess the effect of…
Abstract
Purpose
To investigate the efficacy of Telfaria occidentalis extract as a corrosion inhibitor for mild steel in 2 M HCl and 1 M H2SO4 solutions, respectively, and to assess the effect of temperature and halide additives on the inhibition efficiency.
Design/methodology/approach
Corrosion rate was monitored by careful volumetric measurement of the evolved hydrogen gas at fixed time intervals. Inhibition efficiency was determined by comparing the corrosion rates in the absence and presence of additive. Attempts were made to elucidate the inhibition mechanism from the trend of inhibition efficiency with temperature. The adsorption mode of inhibiting species in the extract was assessed by considering the influence of both acid and halide ions on inhibition efficiency.
Findings
Telfaria occidentalis extract inhibited mild steel corrosion in 2 M HCl and 1 M H2SO4 solutions. Inhibition efficiency increased with extract concentration but decreased with rise in temperature. Synergistic effects increased the efficiency of the extract in the presence of halide additives in the order KCl<KBr<KI. Protonated species in the extract composition played a vital role in the inhibiting action.
Originality/value
This paper provides new information on the inhibiting characteristics of Telfaria occidentalis extract under the specified conditions. This environmentally friendly inhibitor could find possible applications in metal surface anodising and surface coatings.
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E.E. Oguzie, A.I. Onuchukwu, P.C. Okafor and E.E. Ebenso
To appraise the inhibiting effect of Ocimum basilicum extract on aluminium corrosion in 2 M HCl and 2 M KOH solutions, respectively, at 30 and 60°C.
Abstract
Purpose
To appraise the inhibiting effect of Ocimum basilicum extract on aluminium corrosion in 2 M HCl and 2 M KOH solutions, respectively, at 30 and 60°C.
Design/methodology/approach
Corrosion rates were determined using the gas‐volumetric technique and the values obtained in absence and presence of extract was used in calculation of the inhibition efficiency. The mechanism of inhibition was estimated from the trend of inhibition efficiency with temperature.
Findings
Ocimum basilicum extract was found to inhibit aluminium corrosion in the acidic and alkaline environments. Inhibition efficiency increased with extract concentration but decreased with rise in temperature, suggesting physical adsorption of the organic matter on the metal surface. These results were corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from the experimental data at the temperatures studied. Halide additives synergistically improved the inhibition efficiency of the extract.
Originality/value
This paper provides new information on the possible application of Ocimum basilicum extract as an environmentally friendly corrosion inhibitor. The mixed extract – iodide formulation provides an effective means for retarding aluminium corrosion even in highly aggressive alkaline environments.
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E.E. Oguzie, G.N. Onuoha and A.I. Onuchukwu
To investigate the inhibitive effect of Congo red dye (CR) for aluminium corrosion in strong alkaline solutions and evaluate the synergistic effect of halide ions on the…
Abstract
Purpose
To investigate the inhibitive effect of Congo red dye (CR) for aluminium corrosion in strong alkaline solutions and evaluate the synergistic effect of halide ions on the inhibition efficiency.
Design/methodology/approach
Corrosion rates of aluminium test coupons were determined by gravimetric technique at 30 and 60°C. Inhibition efficiencies of the additives (0.01‐5.0 mM CR and 5.0 mM CR+0.5 mM halides) were evaluated by comparing corrosion rates of the test coupons in 2 M KOH solution in the absence and presence of the additives.
Findings
CR inhibited aluminium corrosion in 2 M KOH by physical adsorption of the dye molecules on the corroding metal surface. Maximum efficiency at 30 and 60°C was 31.72 and 19.32 per cent, respectively. Dye adsorption was enhanced in the presence of halides in the order KCl < KBr < KI, with KI increasing efficiency up to 48.63 and 41.70 per cent at 30 and 60°C, respectively.
Research limitations/implications
Further studies to involve variation of dye and halide concentrations for CR+halide systems to determine the best combination for optimum inhibition synergism.
Originality/value
This paper forms part of an extensive database on the inhibition characteristics of organic dyes for corrosion of different metals in various aggressive environments. This is to serve as a guide to possible applications in metal‐surface anodizing and as additives in surface coatings for service in different environments.
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