Trend Of Inhibition Efficiency Research Articles

Inhibition of mild steel corrosion in H2SO4 solution by coconut coir dust extract obtained from different solvent systems and synergistic effect of iodide ions: Ethanol and acetone extracts

Weight loss and electrochemical (open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy) techniques were used to assess the effectiveness of ethanol and acetone extracts of coconut coir dust as corrosion inhibitor for mild steel in 0.5 M H2SO4 solution at 30–60 °C. It was found that both ethanol and acetone extracts of coconut coir dust retard the dissolution of mild steel in 0.5 M H2SO4 solution, but a pronounced effect was noted with ethanol extract. The inhibition efficiency increased with increase in extract concentration but decreased with rise in temperature, which is suggestive of physical adsorption mechanism. Addition of KI was found to synergistically enhance the protective ability of coconut coir dust extracts obtained from both solvent systems investigated. The synergistic effect was confirmed from the synergism parameter (S0) which was found to be greater than unity. Potentiodynamic polarization result suggests that coconut coir extracts functioned as mixed-type inhibitor. The adsorption of coconut coir dust extracts onto the mild steel surface followed Freundlich adsorption isotherm model. The mechanism of physisorption of the extracts onto the steel surface is proposed from the trend of inhibition efficiency with temperature which is corroborated by the values of activation parameters obtained from the experimental data.

Thermodynamic, chemical and electrochemical investigation of pandanus tectorius extract as corrosion inhibitor for steel in sulfuric acid solutions

The corrosion inhibition characteristics of pandanus tectorius extract on corrosion of steel in 1 M H 2 SO 4 were investigated using chemical and electrochemical measurements at various temperatures (30, 40, 50 and 60 °C). The effect of acid concentration on the corrosion rate of steel increases with acid concentration (0.25-2.00 M) showing first order corrosion reaction without changing the reaction mechanism. The results showed that when the concentration of pandanus tectorius extract increased from 5% to 15% (v:v), the rate of steel corrosion is decreased, which indicated that pandanus tectorius extract are good inhibitor for steel corrosion in 1 M H 2 SO 4 at 30 °C and attains 88.02% at 15% ( v : v ) from weight loss method. Electrochemical results showed that the investigated extract was acted as mixed type inhibitor. The free energy of adsorption Δ G ads for pandanus tectorius , indicates that the process was spontaneous and physically adsorbed (physisorption) onto the steel surface. Also, scanning electron microscopy (SEM) is used to support the obtained result. The trend of inhibition efficiency with temperature suggests physical adsorption of this extract on the corroding steel surface. Thermodynamic functions ∆ E app , ∆ H * and ∆ S * has been calculated and are discussed.

Inhibitive effect of ceftazidime on corrosion of mild steel in hydrochloric acid solution

The corrosion inhibition properties of ceftadizime (CZD) for mild steel corrosion in HCl solution were analysed by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and gravimetric methods. These results were supplemented by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Mixed mode of adsorption (physisorption and chemisorption) is proposed for the inhibition and the process followed the Langmuir adsorption isotherm and kinetic/thermodynamic model of El-Awady et al. The mechanism of adsorption inhibition and type of adsorption isotherm were proposed from the trend of inhibition efficiency with temperature, E a and Δ G ads ° . Potentiodynamic polarization study clearly revealed that CZD acted as mixed type inhibitor. The experimental data showed a frequency distribution and therefore a modelling element with frequency dispersion behaviour and a constant phase element (CPE) have been used.

Spondias mombin L. as a green corrosion inhibitor for aluminium in sulphuric acid: Correlation between inhibitive effect and electronic properties of extracts major constituents using density functional theory

The inhibition of aluminium in 0.5M H2SO4 by extracts of Spondias mombin L. was investigated using the standard gravimetric technique at 30–60°C. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition. It was found that the S. mombin L. extract acts as an inhibitor for acid-induced corrosion of aluminium. Inhibition efficiency (%I) of the extract increased with an increase in concentration of the S. mombin L. extract but decreased with temperature. Furthermore, inhibition efficiency (%I) synergistically increased on addition of potassium iodide. Inhibitor adsorption characteristics were approximated by Langmuir adsorption isotherm at all the concentrations and temperatures studied. The mechanism of physical adsorption is proposed from the trend of inhibition efficiency with temperature and from the calculated values of Gibbs free energy, activation energy and heat of adsorption. Quantum chemical calculations were performed using the density functional theory at B3LYP/6-31G (d) level of theory to find out whether a clear link exists between the inhibitive effect of the extract and the electronic properties of its main constituents.

Synergistic inhibition effect of polyethylene glycol–polyvinyl pyrrolidone blends for mild steel corrosion in sulphuric acid medium

AbstractThe corrosion inhibition of mild steel in sulphuric acid solution in the presence of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP), and their blends was investigated using weight loss and hydrogen evolution techniques at temperature range of 30–60°C. It was found that inhibition efficiency (η%) increases with increase in concentration of the homopolymers and decreases with increase in temperature. Inhibition efficiency was found to be synergistically enhanced on blending the two polymers with highest inhibition efficiency obtained for (PEG : PVP) blending ratio of 1 : 3. The experimental data obtained fitted well into Temkin adsorption isotherm model. Physical adsorption mechanism is proposed from the trend of inhibition efficiency with temperature. The proposed mechanism is also corroborated by kinetic and thermodynamic parameters obtained. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

INHIBITION OF MILD STEEL CORROSION IN H2SO4 USING EXUDATE GUM FROM PACHYLOBUS EDULIS AND SYNERGISTIC POTASSIUM HALIDE ADDITIVES

The corrosion inhibitive effects of Pachylobus edulis exudate gum for mild steel in 2 M H2SO4 and influence of potassium halide additives on the inhibition efficiency were investigated using hydrogen evolution and thermometric methods at 30°–60°C. Inhibition efficiency was determined by comparing the corrosion rates in the absence and presence of additives. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition. It was found that the exudate gum acts as an inhibitor for acid-induced corrosion of mild steel. Inhibition efficiency (%I) of the exudate gum increased with an increase in concentration of the exudate gum and synergistically increased on addition of potassium halides but decreased with increase in temperature. Inhibitor adsorption characteristics were approximated by Temkin adsorption isotherm at all the concentrations and temperatures studied. The phenomenon of physical adsorption is proposed from the activation parameters obtained.

Inhibition of mild steel corrosion in HCl using pineapple leaves (Ananas comosus L.) extract

The corrosion inhibition of mild steel in HCl by pineapple leaves extract was studied using weight loss and hydrogen evolution methods at 30–60 °C. It was found that the pineapple leaves extract inhibited the acid induced corrosion of mild steel. The inhibition efficiency increases with increase in the extract concentration and with rise in temperature. Adsorption of the extract was found to obey Langmuir adsorption isotherm at all the concentrations and temperatures studied. The mechanism of chemical adsorption is proposed from the trend of inhibition efficiency with temperature. The proposed mechanism was also corroborated by kinetic and thermodynamic parameters obtained.

Inhibitive effect of methyl green dye on the corrosion of low carbon steel in acidic media

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 ad...

Synergistic effect of methyl red dye and potassium iodide on inhibition of corrosion of carbon steel in 0.5 M H2SO4

PurposeThis paper aims to show the effectiveness of methyl red (MR) alone and in combination with KI as corrosion inhibitor for carbon steel in 0.5 M H2SO4.Design/methodology/approachCorrosion rates charge transfer resistance values were determined using gravimetric and electrochemical techniques. The efficiency of inhibition was calculated by comparing corrosion rates and charge transfer resistance values in absence and presence of the inhibitor, while the mechanism of inhibition was proposed by considering temperature influence on corrosion and inhibition processes.FindingsThe inhibition efficiency of MR increased with concentration and synergistically increased in the presence of the KI. Polarisation curves reveal that MR is a mixed type inhibitor. Changes in impedance parameters were indicative of adsorption of MR on the metal surface. The trend of inhibition efficiency with temperature suggests that inhibitor molecules are physically adsorbed on the corroding metal surface in the absence of KI and chemically adsorbed in its presence. MR was found to obey Langmuir adsorption isotherm both with and without KI.Originality/valueElectrochemical techniques have been used for the first time to study synergistic effect of MR dye and potassium iodide on inhibition of corrosion of carbon steel in H2SO4.The results suggest that the mixture (MR + KI) could find practical application in corrosion control in aqueous acidic environment.

Inhibition of mild steel corrosion in acidic medium using synthetic and naturally occurring polymers and synergistic halide additives

The corrosion inhibition of mild steel in H 2SO 4 in the presence of gum arabic (GA) (naturally occurring polymer) and polyethylene glycol (PEG) (synthetic polymer) was studied using weight loss, hydrogen evolution and thermometric methods at 30–60 °C. PEG was found to be a better inhibitor for mild steel corrosion in acidic medium than GA. The effect of addition of halides (KCl, KBr and KI) was also studied. Results obtained showed that inhibition efficiency ( I%) increased with increase in GA and PEG concentration, addition of halides and with increase in temperature. Increase in inhibition efficiency ( I%) and degree of surface coverage ( θ) was found to follow the trend Cl − < Br − < I − which indicates that the radii and electronegativity of the halide ions play a significant role in the adsorption process. GA and PEG alone and in combination with halides were found to obey Temkin adsorption isotherm. Phenomenon of chemical adsorption is proposed from the trend of inhibition efficiency with temperature and values Δ G ads 0 obtained. The synergism parameter, S I evaluated is found to be greater than unity indicating that the enhanced inhibition efficiency caused by the addition of halides is only due to synergism.

Adsorption and corrosive inhibitive properties ofVigna unguiculatain alkaline and acidic media

PurposeTo investigate the adsorption behaviour and inhibitive effect ofVigna unguiculata(VU) extract (agricultural waste material) for aluminium corrosion in 0.5 M NaOH and H2SO4.Design/methodology/approachThe inhibitive effect of the plant extract was assessed using weight loss method at 30 and 60oC. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption.FindingsVU 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.Research limitations/implicationsThe mechanistic aspect of the corrosion inhibition can be better understood using electrochemical studies such as polarization and AC impedance spectra.Practical implicationsThe findings may be useful in metal surface anodizing and metal coating.Originality/valueThis paper provides new information on the possible application of VU extract as eco‐friendly inhibitor. It has not been reported elsewhere.

Eco‐friendly corrosion inhibitors: inhibitive action of ethanol extracts of Garcinia kola for the corrosion of mild steel in H2SO4 solutions

PurposeThis 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/approachThe 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.FindingsThe 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/implicationsFurther investigations involving electrochemical studies such as polarization method will provide further enlightenment on the mechanistic aspect of the corrosion inhibition.Originality/valueThis 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.

Effect of ascorbic acid on mild steel dissolution in sulphuric acid solution investigated by electrochemical polarization and surface probe techniques

The effect of ascorbic acid (AA) on the corrosion of mild steel in sulphuric acid solution has been investigated by open circuit potential (OCP) and polarization measurements. AA was observed to shift the OCP to more positive potentials with increasing concentration. The polarization curves revealed that AA inhibited the anodic metal dissolution reaction, although this effect became negligible at high anodic overpotentials. The trend of inhibition efficiency with concentration showed that efficiency increased rapidly at low concentrations, remained almost steady at intermediate concentrations and increased again at high concentrations. The mechanism of inhibition was considered in terms of initial chemisorption of AA according to the Temkin isotherm, followed by formation of chelate compounds with Fe2+ ions at high concentrations. EDS and AFM analyses of the electrode surface support the proposed inhibition mechanisms.

Adsorption and corrosion inhibitive properties of Azadirachta indica in acid solutions

PurposeTo 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/approachThe 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.FindingsAzadirachta 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/valueThis 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.

Gum arabic as a potential corrosion inhibitor for aluminium in alkaline medium and its adsorption characteristics

PurposeTo investigate the inhibitive effect of gum arabic (GA) for the corrosion of aluminium in alkaline (NaOH) medium and determine its adsorption characteristics. The present work is another trial to find a cheap and environmentally safe inhibitor for aluminium corrosion.Design/methodology/approachThe inhibition efficiency (%I) has been evaluated using the hydrogen evolution (via the gasometric assembly) and the thermometric methods at 30 and 40°C. The concentrations of GA (inhibitor) used were 0.1‐0.5 g/l and the concentrations of NaOH (the corrodent) were 0.1‐2.5 M. The mechanism of adsorption inhibition and type of adsorption isotherms were proposed from the trend of inhibition efficiency with temperature, Ea, ΔGads and Qads values.FindingsGA inhibited the corrosion of aluminium in NaOH solutions. The inhibition efficiency increased with increase in GA concentration and with increase in temperature. Phenomenon of chemical adsorption is proposed for the inhibition and the process followed the Langmuir and Freundlich adsorption isotherms. The results obtained in this study for the %I were comparable for the two methods used and were corroborated by kinetic and thermodynamic parameters evaluated from the experimental data.Research limitations/implicationsFurther investigations involving electrochemical studies such as polarization method will enlighten more on the mechanistic aspect of the corrosion inhibition.Originality/valueThis paper provides new information on the possible application of GA as an environmentally friendly corrosion inhibitor even in highly aggressive alkaline environments. It has not been published elsewhere.

Corrosion inhibition and adsorption behaviour of Ocimum basilicum extract on aluminium

PurposeTo 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/approachCorrosion 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.FindingsOcimum 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/valueThis 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.

Inhibition of acid corrosion of mild steel by Telfaria occidentalis extract

PurposeTo 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/approachCorrosion 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.FindingsTelfaria 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&lt;KBr&lt;KI. Protonated species in the extract composition played a vital role in the inhibiting action.Originality/valueThis 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.

Inhibitory mechanism of mild steel corrosion in 2 M sulphuric acid solution by methylene blue dye

Methylene blue dye (MB) was investigated as a corrosion inhibitor for mild steel in 2 M sulphuric acid solution using gravimetric and thermometric techniques. The inhibition efficiency of MB increased with concentration and synergistically increased in the presence of the halide additives, namely KCl, KBr and KI. The trend of inhibition efficiency with temperature suggests that inhibitor molecules are physically adsorbed on the corroding metal surface at lower concentration (0.01–0.5 mM), and chemically adsorbed at higher concentration (1.0–5.0 mM). These results were further corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from experimental data at the temperatures studied. MB was found to obey Langmuir and Frumkin adsorption isotherms in the concentration range investigated.