The corrosion protection of mild steel in 1 M H3PO4 solution by apricot juice was studied
at different temperatures by weight loss technique. Adsorption, activation and statistical studies
were addressed in this work. Adsorption studies showed that inhibitor adsorbed on metal surface
according to Langmuir isotherm. Average value of heat of adsorption was 14.93 kJ/mol indicates
a spontaneous physical adsorption on metal surface. Activation parameters did not changed with
addition of inhibitor indicates that there is no change in reaction mechanism. Analysis of variance
(ANOVA) was also applied. This analysis showed that the corrosion rate influenced by temperature,
inhibitor concentration and combined interaction of them.
Ginger extract as corrosion inhibitor from natural resources was studied to prevent corrosion of mild steel in acid media. Ginger rhizome was extracted to produce green corrosion inhibitor (G-1) while ginger powder bought at supermarket was also extracted to form a green corrosion inhibitor (G-2). Effectiveness of inhibitor in preventing corrosion process of mild steel was studied in 1.0 M of hydrochloric acid
The effect of ethanol extract of leaves of Conyza Dicorides plant on the corrosion inhibition
of mild steel in 1M HCl solution was investigated by weight loss and electrochemical polarization
techniques at temperature range (25–65 ̊C). The Results obtained showed that the percentage
inhibition efficiency increases with the increasing of inhibitor concentration and decreases with the
increasing of temperature. At a concentration of 2 g/L, the percentage inhibition efficiency reached
about (94.87%) at 25 ̊C. The thermodynamic activation functions of dissolution process and
adsorption parameters were calculated and discussed. Adsorption of the additive was found to follow
the Langmuir adsorption isotherm.
Effect of plant extracts on corrosion rate of mild steel in acidic mediumPremier Publishers
2.5ml Ethanol is used on plant extracts of locus bean (parkiabiglobosa) and banana sap (musaparadisiaca) as corrosion inhibitors for mild steel in 1M dilute HCl was investigated using weight loss techniques. Corrosion tests were first carried out for 1 and 3 hrs of immersion time respectively at various concentrations of extracts (0.5ml, 1.0ml, 1.5ml, 2.0ml and 2.5ml) and 2.5ml were used as corrosion inhibitors and at different temperatures (38oC, 45oC and 55oC). Results showed that the minimum corrosion rate obtained for 1 hr at 38oC with extract of Pakiabiglobosa is 0.85×10-4g/cm3/min and efficiency of 18.75% for 1hr, while at 55oC the corrosion rate was 4.37×10-4 g/cm3/min and efficiency of 33%. With ethanol extract of banana sap, minimum corrosion rate and efficiency recorded at 38°C were (4.16×10-4 g/cm3/min and efficiency of (22.1%), while at 55oC they were (0.83×10-4 g/cm3/min) and (7.6%) respectively. From these results, it is concluded that extracts of locust bean and banana sap can be successfully used as corrosion inhibitors in specified acidic medium.
Corrosion Inhibition of Carbon Steel in Chloride and Sulfate SolutionsIJERA Editor
Corrosion is a major problem in industry and in infrastructure; a huge sum of expenditure every year is spent on
preventing, retarding, and repairing its damages. This work studies the engineering of an inhibitor for carbon
steel metal used in the cooling systems containing high concentration of chloride and sulfate ions. For this
purpose, the synergy between the dichromate, molybdate and nitrite inhibitors is examined and optimized to the
best results. Moreover, care was taken that the proposed inhibitor is compliant with the environmental laws and
regulations.
Red Dragon Fruit (Selenicereus costaricensis) Waste Peels as Corrosion Inhibi...Innspub Net
Metal corrosion is brought about by the oxidation of atoms on the surface, resulting in irreversible damage to structures at staggering costs. Hence, the search for efficient and cost-effective corrosion inhibitors is relevant. Waste agricultural by-products which have no food or economic value serve as good potential sources for these environmentally benign corrosion inhibitors. Ethanolic extracts of Red Dragon Fruit (RDF) have been previously reported to contain high amounts of flavonoids and polyphenols, which can manifest inhibitory activity against corrosion brought about by aggressive electrolytes. In this study, the ethanolic extract of Selenicereus costaricensis waste peels was tested for its anti-corrosion property using weight loss method. We have also probed its performance as a potential corrosion inhibitor at a range of different temperatures from 303 to 343 K. The calculated inhibition efficiency of 2% RDF was 97%. Thermodynamic studies reveal that increasing inhibitor concentration raises the activation parameters of mild steel in an acidic medium such as activation energy (Ea) and changes in enthalpy (DHo) and entropy (DSo). It was found that the corrosion inhibition process using RDF waste peel extract mainly occurs under diffusion control. Moreover, increased immersion time, inhibitor concentration, and temperature led to increased inhibition efficiency. The spontaneous process (DGoads = -23.47 kJ/mol) of adsorption of RDF on mild steel surfaces obeys the Langmuir isotherm model.
A Study of the Corrosion Inhibition of Mild Steel in 0.5M Tetraoxosulphate (V...IJAEMSJORNAL
A comparative study of the corrosion inhibition performance of Alstonia boonei leaves extract in 0.5M tetraoxosulphate (VI) acid at different temperatures (30ᵒC, 50ᵒC and 70ᵒC) was undertaken. The results showed that Alstonia boonei leaves extract was more efficient as a corrosion inhibitor at 30ᵒC compared to temperatures of 50ᵒC and 70ᵒC.The adsorption of Alstonia boonei leaves extract was found to obey Langmuir adsorption isotherm at all temperatures (30ᵒC, 50ᵒC and 70ᵒC), but did not obey Freundlich adsorption isotherm at all temperatures. A study of the effect of temperature on corrosion rate and inhibition efficiency showed that corrosion rate increased with increase in temperature, while the inhibition efficiency decreased with increase in temperature.
Ginger extract as corrosion inhibitor from natural resources was studied to prevent corrosion of mild steel in acid media. Ginger rhizome was extracted to produce green corrosion inhibitor (G-1) while ginger powder bought at supermarket was also extracted to form a green corrosion inhibitor (G-2). Effectiveness of inhibitor in preventing corrosion process of mild steel was studied in 1.0 M of hydrochloric acid
The effect of ethanol extract of leaves of Conyza Dicorides plant on the corrosion inhibition
of mild steel in 1M HCl solution was investigated by weight loss and electrochemical polarization
techniques at temperature range (25–65 ̊C). The Results obtained showed that the percentage
inhibition efficiency increases with the increasing of inhibitor concentration and decreases with the
increasing of temperature. At a concentration of 2 g/L, the percentage inhibition efficiency reached
about (94.87%) at 25 ̊C. The thermodynamic activation functions of dissolution process and
adsorption parameters were calculated and discussed. Adsorption of the additive was found to follow
the Langmuir adsorption isotherm.
Effect of plant extracts on corrosion rate of mild steel in acidic mediumPremier Publishers
2.5ml Ethanol is used on plant extracts of locus bean (parkiabiglobosa) and banana sap (musaparadisiaca) as corrosion inhibitors for mild steel in 1M dilute HCl was investigated using weight loss techniques. Corrosion tests were first carried out for 1 and 3 hrs of immersion time respectively at various concentrations of extracts (0.5ml, 1.0ml, 1.5ml, 2.0ml and 2.5ml) and 2.5ml were used as corrosion inhibitors and at different temperatures (38oC, 45oC and 55oC). Results showed that the minimum corrosion rate obtained for 1 hr at 38oC with extract of Pakiabiglobosa is 0.85×10-4g/cm3/min and efficiency of 18.75% for 1hr, while at 55oC the corrosion rate was 4.37×10-4 g/cm3/min and efficiency of 33%. With ethanol extract of banana sap, minimum corrosion rate and efficiency recorded at 38°C were (4.16×10-4 g/cm3/min and efficiency of (22.1%), while at 55oC they were (0.83×10-4 g/cm3/min) and (7.6%) respectively. From these results, it is concluded that extracts of locust bean and banana sap can be successfully used as corrosion inhibitors in specified acidic medium.
Corrosion Inhibition of Carbon Steel in Chloride and Sulfate SolutionsIJERA Editor
Corrosion is a major problem in industry and in infrastructure; a huge sum of expenditure every year is spent on
preventing, retarding, and repairing its damages. This work studies the engineering of an inhibitor for carbon
steel metal used in the cooling systems containing high concentration of chloride and sulfate ions. For this
purpose, the synergy between the dichromate, molybdate and nitrite inhibitors is examined and optimized to the
best results. Moreover, care was taken that the proposed inhibitor is compliant with the environmental laws and
regulations.
Red Dragon Fruit (Selenicereus costaricensis) Waste Peels as Corrosion Inhibi...Innspub Net
Metal corrosion is brought about by the oxidation of atoms on the surface, resulting in irreversible damage to structures at staggering costs. Hence, the search for efficient and cost-effective corrosion inhibitors is relevant. Waste agricultural by-products which have no food or economic value serve as good potential sources for these environmentally benign corrosion inhibitors. Ethanolic extracts of Red Dragon Fruit (RDF) have been previously reported to contain high amounts of flavonoids and polyphenols, which can manifest inhibitory activity against corrosion brought about by aggressive electrolytes. In this study, the ethanolic extract of Selenicereus costaricensis waste peels was tested for its anti-corrosion property using weight loss method. We have also probed its performance as a potential corrosion inhibitor at a range of different temperatures from 303 to 343 K. The calculated inhibition efficiency of 2% RDF was 97%. Thermodynamic studies reveal that increasing inhibitor concentration raises the activation parameters of mild steel in an acidic medium such as activation energy (Ea) and changes in enthalpy (DHo) and entropy (DSo). It was found that the corrosion inhibition process using RDF waste peel extract mainly occurs under diffusion control. Moreover, increased immersion time, inhibitor concentration, and temperature led to increased inhibition efficiency. The spontaneous process (DGoads = -23.47 kJ/mol) of adsorption of RDF on mild steel surfaces obeys the Langmuir isotherm model.
A Study of the Corrosion Inhibition of Mild Steel in 0.5M Tetraoxosulphate (V...IJAEMSJORNAL
A comparative study of the corrosion inhibition performance of Alstonia boonei leaves extract in 0.5M tetraoxosulphate (VI) acid at different temperatures (30ᵒC, 50ᵒC and 70ᵒC) was undertaken. The results showed that Alstonia boonei leaves extract was more efficient as a corrosion inhibitor at 30ᵒC compared to temperatures of 50ᵒC and 70ᵒC.The adsorption of Alstonia boonei leaves extract was found to obey Langmuir adsorption isotherm at all temperatures (30ᵒC, 50ᵒC and 70ᵒC), but did not obey Freundlich adsorption isotherm at all temperatures. A study of the effect of temperature on corrosion rate and inhibition efficiency showed that corrosion rate increased with increase in temperature, while the inhibition efficiency decreased with increase in temperature.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Investigative studies on the inhibitive effects of Newbouldialaevis extracts ...researchinventy
The inhibitive effects ofNewbouldiaLaevis (NL) leaf extract and magnetic field on copper corrosion in 0.5M H2SO4 aqueous solution were investigated experimentally by gravimetric technique and theoretically using Quantum Chemical calculations. The results show that both NL and the magnetic field caused reduction in corrosion rate. The inhibition efficiency increased with concentration. The magnetic field caused greater increase in the inhibition efficiency. Temperature increase caused a decrease in inhibition efficiency. The activation energy is low and oscillates, possibly due to error factor from non-linearity of the Arrhenius plot. Among the tested isotherms, Langmuir has the highest correlation coefficient of 0.9963 and 0.7935 with and without magnet field respectively. The magnetic field increased the change in free energy, caused the reaction to become spontaneous, one mole of the inhibitor to replace 4 moles of water mole while reducing the number of monolayer of the inhibitor on the metal. The quantum chemical calculations performed on newbouldiaquinone and lapacholconstituents of NL showed that lapachol contributed more to the inhibition efficiency due its low binding energy, high dipole moment, chemical softness and fractional electron transfer. The magnetic field and temperature played opposite roles.
Combination of urea-Sn+2 in SCP solution was examined as a corrosion inhibitor for concrete reinforced steel by potentiodynamicpolarization, surface synergist parameter and cyclic voltammetry methods comparing with urea–Zn+2 combination. A synergism parameter (SI) indicated a synergistic effect between urea and Sn+2was exist. Polarization study revealed that formulation consisting of 300 ppm urea+50 ppm Sn+2 in SCP solution provided inhibition efficiency (IF) of 85.93% while 300 ppm urea +50 ppm Zn+2 provided 82.3% IF, and this combination acts as anodic type inhibitor. Cyclic voltammetry curves showed that the steel samples immersed in this formulation has low tendency to pitting corrosion. From these results it can be concluded that urea – Sn+2 inhibitor formulation is a good corrosion n inhibitor for concrete reinforced steel, it can maintain stable passive film on steel surface even in the presence of aggressive chloride ions so it can be used instead of the high toxicityZn+2 inhibitor to improve the corrosion inhibition of urea fertilizer inhibitor.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Chemical and Electrochemical Study on the Effectively of Melilotus Officinali...paperpublications3
Abstract: Melilotus officinalis Extract (M.O.E.) was investigated as a green corrosion inhibitor for Aluminium alloy in 1 M HCl solution using weight loss, hydrogen evolution, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Surface morphology was tested using scanning electron microscope (SEM). The effect of temperature on corrosion behavior with addition of different concentrations was studied in the temperature range of 25-45 ºC by weight loss. Polarization curves reveal that the investigated extract is a mixed inhibitor. The inhibition efficiency was found to increase with increase the investigated extract concentration and increase with increasing solution temperature. The adsorption of the inhibitor on Aluminium alloy surface was found to obey the Tenkin’s adsorption isotherm. The activation and adsorption parameters were calculated and discussed. The results obtained from chemical and electrochemical techniques are in good agreement.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effect of Solution heat treatment on microstructure and "pitting corrosion "of the
austenitic stainless steel (316 L) is actualized.Agreeing to "ASTM (G71-31)" a figure
of samples for corrosion inspection were prepared with the dimensions of (15 * 15 *
3) mm then divided into sets and heated in electrical furnace at (1060C )for half
hour some of them were quenched in distilled water and the other quench by distil
water with (PVA)which added at different percentage(0.3,0.5,0.7,0.9%)gm/liter .
Microstructure of all specimens were examined also the corrosion conduct using
simulation body fluid. Results of microstructure examination show appearance of
many phases. The corrosion rate of all specimens which subjected to solution heat
treatment was higher comparing with the corrosion rate of base alloy. Solution heat
treatment in distil water and in distil water with high percentage of PVA (0.7, 0.9)
contributed in increases in corrosion rate but when decreases the percentage to (
0.3,0.5) the corrosion rate was decreased due to the increases in cooling rate .
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Chemical and electrochemical studies of ranitidine as a corrosion inhibitor f...Premier Publishers
The corrosion inhibition of ranitidine on mild steel in hydrochloric acid medium was studied employing chemical and electrochemical methods. The results showed that the studied compound possessed good interaction on the metal surface and control both anodic and cathodic reactions. Studies pertaining to the determination of corrosion rate, percentage inhibition efficiency and variation of inhibitor concentration and temperature for the corrosion control process. Both anodic and cathodic polarized potentials were measured under galvanostatic and linear polarization techniques. The corrosion current density, corrosion potentials, Tafel slops and percentage inhibition efficiency were calculated. Thermodynamic parameters for the adsorption process were calculated and interpreted. The percentage inhibition efficiency obtained from both the methods was good agreement with each other. The corrosion protection was explained on the basis of adsorption of inhibitors on the metal surface. Adsorption of a compound on the mild steel surface was confirmed by FTIR spectra.
Thymus Vulgarize extract (TVE) was reported to be good corrosion inhibitor for copper and
brass in acid media. This paper presents experimental study to investigate the efficiency of Thyme
leaves extract as corrosion inhibitor for concrete reinforcing steel samples exposed to alkaline
solution consisting of 2% KOH and 3% NaCl which is a simulation to the chloride contaminated
concrete pore solution (SCP) using open circuit potential and potentiodynamic polarization
technique. Various concentration (100 ml/L, 150 ml/L, 250 ml/L) of TVE were used in this
experiment. Open circuit potential (OCP) measurements indicated a shifting in potential toward
noble direction for steel samples immersed in SCP solution containing TVE compared with control
sample.
Done by: Sukari group
School name; Omar Bin Khattab secondary school for boys.
The project aimed to study how the investigated triazole derivative controls the corrosion of mild steel in sulfuric acid solutions. The corrosion rates in absence and presence of different concentrations of inhibitor will be measured using weight loss and potentiodynamic polarization techniques. Also, the effect of inhibitor on surface morphology of carbon steel will be investigated using scanning electron microscope.
Corrosion Behaviour of 6061 Al-SiC Composites in KOH MediumEditor IJCATR
The present research work deals with the corrosion behaviour of 6061 Al-15% (vol) SiC(P) composites. The addition of the
reinforcement like SiC to Aluminium has been reported to decrease the corrosion resistance of the matrix due to several reasons, one
of them being galvanic action between the reinforcement and the matrix. In the present work, the corrosion behaviour of 6061 Al-15%
(vol) SiC(P) composites in KOH at different concentration (0.5M, 1M, 1.5M) and different temperature (300C, 350C, 400C, 450C, 500C)
was determined by Tafel extrapolation technique. The inhibition action of 8-Hydroxyquinoline on corrosion behaviour of 6061 Al-
15% (vol) SiC(P) composites in KOH at different concentration of inhibitor (200ppm, 400ppm); different concentration of medium
(0.5M, 1M,1.5M) and different temperature (300C, 350C, 400C, 450C, 500C) was investigated. The results indicate that corrosion rate
of Al-SiC composite in KOH increases as the concentration of medium increases and also as temperature of medium increases. The
results indicate that the inhibitor is moderately effective in inhibiting the corrosion of 6061 Al-15% (vol) SiC(P) composites. As the
inhibitor concentration increases, the corrosion rate decreases. The surface morphology of the metal surface was investigated using
scanning electron microscope (SEM). Activation energy was evaluated using Arrhenius equation, and enthalpy of activation and
entropy of activation values were calculated using transition state equation
Experimental and theoretical investigations of some pyrazolo-pyrimidine deriv...Al Baha University
The anticorrosion performance of three pyrazolo-pyrimidine derivatives, namely, 4-amino pyrazolo-pyrimidine
(APP), 4-hydroxy pyrazolo-pyrimidine (HPP), and 4-mercapto pyrazolo-pyrimidine (MPP) on copper in 0.5M
H2SO4 solution have been investigated using electrochemical, surface analysis, as well as theoretical techniques.
The results indicate that these inhibitors have largely inhibited the corrosion of copper and the inhibition efficiency
increased with increasing concentration. Moreover, the inhibitors adsorb on copper surface following
Langmuir adsorption isotherm. XPS analysis were performed for describing the bonding characteristics between
inhibitors and copper substrate. Furthermore, DFT and molecular dynamics simulation calculations were applied
to further explain the anti-corrosion mechanism.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Investigative studies on the inhibitive effects of Newbouldialaevis extracts ...researchinventy
The inhibitive effects ofNewbouldiaLaevis (NL) leaf extract and magnetic field on copper corrosion in 0.5M H2SO4 aqueous solution were investigated experimentally by gravimetric technique and theoretically using Quantum Chemical calculations. The results show that both NL and the magnetic field caused reduction in corrosion rate. The inhibition efficiency increased with concentration. The magnetic field caused greater increase in the inhibition efficiency. Temperature increase caused a decrease in inhibition efficiency. The activation energy is low and oscillates, possibly due to error factor from non-linearity of the Arrhenius plot. Among the tested isotherms, Langmuir has the highest correlation coefficient of 0.9963 and 0.7935 with and without magnet field respectively. The magnetic field increased the change in free energy, caused the reaction to become spontaneous, one mole of the inhibitor to replace 4 moles of water mole while reducing the number of monolayer of the inhibitor on the metal. The quantum chemical calculations performed on newbouldiaquinone and lapacholconstituents of NL showed that lapachol contributed more to the inhibition efficiency due its low binding energy, high dipole moment, chemical softness and fractional electron transfer. The magnetic field and temperature played opposite roles.
Combination of urea-Sn+2 in SCP solution was examined as a corrosion inhibitor for concrete reinforced steel by potentiodynamicpolarization, surface synergist parameter and cyclic voltammetry methods comparing with urea–Zn+2 combination. A synergism parameter (SI) indicated a synergistic effect between urea and Sn+2was exist. Polarization study revealed that formulation consisting of 300 ppm urea+50 ppm Sn+2 in SCP solution provided inhibition efficiency (IF) of 85.93% while 300 ppm urea +50 ppm Zn+2 provided 82.3% IF, and this combination acts as anodic type inhibitor. Cyclic voltammetry curves showed that the steel samples immersed in this formulation has low tendency to pitting corrosion. From these results it can be concluded that urea – Sn+2 inhibitor formulation is a good corrosion n inhibitor for concrete reinforced steel, it can maintain stable passive film on steel surface even in the presence of aggressive chloride ions so it can be used instead of the high toxicityZn+2 inhibitor to improve the corrosion inhibition of urea fertilizer inhibitor.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Chemical and Electrochemical Study on the Effectively of Melilotus Officinali...paperpublications3
Abstract: Melilotus officinalis Extract (M.O.E.) was investigated as a green corrosion inhibitor for Aluminium alloy in 1 M HCl solution using weight loss, hydrogen evolution, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Surface morphology was tested using scanning electron microscope (SEM). The effect of temperature on corrosion behavior with addition of different concentrations was studied in the temperature range of 25-45 ºC by weight loss. Polarization curves reveal that the investigated extract is a mixed inhibitor. The inhibition efficiency was found to increase with increase the investigated extract concentration and increase with increasing solution temperature. The adsorption of the inhibitor on Aluminium alloy surface was found to obey the Tenkin’s adsorption isotherm. The activation and adsorption parameters were calculated and discussed. The results obtained from chemical and electrochemical techniques are in good agreement.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effect of Solution heat treatment on microstructure and "pitting corrosion "of the
austenitic stainless steel (316 L) is actualized.Agreeing to "ASTM (G71-31)" a figure
of samples for corrosion inspection were prepared with the dimensions of (15 * 15 *
3) mm then divided into sets and heated in electrical furnace at (1060C )for half
hour some of them were quenched in distilled water and the other quench by distil
water with (PVA)which added at different percentage(0.3,0.5,0.7,0.9%)gm/liter .
Microstructure of all specimens were examined also the corrosion conduct using
simulation body fluid. Results of microstructure examination show appearance of
many phases. The corrosion rate of all specimens which subjected to solution heat
treatment was higher comparing with the corrosion rate of base alloy. Solution heat
treatment in distil water and in distil water with high percentage of PVA (0.7, 0.9)
contributed in increases in corrosion rate but when decreases the percentage to (
0.3,0.5) the corrosion rate was decreased due to the increases in cooling rate .
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Chemical and electrochemical studies of ranitidine as a corrosion inhibitor f...Premier Publishers
The corrosion inhibition of ranitidine on mild steel in hydrochloric acid medium was studied employing chemical and electrochemical methods. The results showed that the studied compound possessed good interaction on the metal surface and control both anodic and cathodic reactions. Studies pertaining to the determination of corrosion rate, percentage inhibition efficiency and variation of inhibitor concentration and temperature for the corrosion control process. Both anodic and cathodic polarized potentials were measured under galvanostatic and linear polarization techniques. The corrosion current density, corrosion potentials, Tafel slops and percentage inhibition efficiency were calculated. Thermodynamic parameters for the adsorption process were calculated and interpreted. The percentage inhibition efficiency obtained from both the methods was good agreement with each other. The corrosion protection was explained on the basis of adsorption of inhibitors on the metal surface. Adsorption of a compound on the mild steel surface was confirmed by FTIR spectra.
Thymus Vulgarize extract (TVE) was reported to be good corrosion inhibitor for copper and
brass in acid media. This paper presents experimental study to investigate the efficiency of Thyme
leaves extract as corrosion inhibitor for concrete reinforcing steel samples exposed to alkaline
solution consisting of 2% KOH and 3% NaCl which is a simulation to the chloride contaminated
concrete pore solution (SCP) using open circuit potential and potentiodynamic polarization
technique. Various concentration (100 ml/L, 150 ml/L, 250 ml/L) of TVE were used in this
experiment. Open circuit potential (OCP) measurements indicated a shifting in potential toward
noble direction for steel samples immersed in SCP solution containing TVE compared with control
sample.
Done by: Sukari group
School name; Omar Bin Khattab secondary school for boys.
The project aimed to study how the investigated triazole derivative controls the corrosion of mild steel in sulfuric acid solutions. The corrosion rates in absence and presence of different concentrations of inhibitor will be measured using weight loss and potentiodynamic polarization techniques. Also, the effect of inhibitor on surface morphology of carbon steel will be investigated using scanning electron microscope.
Corrosion Behaviour of 6061 Al-SiC Composites in KOH MediumEditor IJCATR
The present research work deals with the corrosion behaviour of 6061 Al-15% (vol) SiC(P) composites. The addition of the
reinforcement like SiC to Aluminium has been reported to decrease the corrosion resistance of the matrix due to several reasons, one
of them being galvanic action between the reinforcement and the matrix. In the present work, the corrosion behaviour of 6061 Al-15%
(vol) SiC(P) composites in KOH at different concentration (0.5M, 1M, 1.5M) and different temperature (300C, 350C, 400C, 450C, 500C)
was determined by Tafel extrapolation technique. The inhibition action of 8-Hydroxyquinoline on corrosion behaviour of 6061 Al-
15% (vol) SiC(P) composites in KOH at different concentration of inhibitor (200ppm, 400ppm); different concentration of medium
(0.5M, 1M,1.5M) and different temperature (300C, 350C, 400C, 450C, 500C) was investigated. The results indicate that corrosion rate
of Al-SiC composite in KOH increases as the concentration of medium increases and also as temperature of medium increases. The
results indicate that the inhibitor is moderately effective in inhibiting the corrosion of 6061 Al-15% (vol) SiC(P) composites. As the
inhibitor concentration increases, the corrosion rate decreases. The surface morphology of the metal surface was investigated using
scanning electron microscope (SEM). Activation energy was evaluated using Arrhenius equation, and enthalpy of activation and
entropy of activation values were calculated using transition state equation
Experimental and theoretical investigations of some pyrazolo-pyrimidine deriv...Al Baha University
The anticorrosion performance of three pyrazolo-pyrimidine derivatives, namely, 4-amino pyrazolo-pyrimidine
(APP), 4-hydroxy pyrazolo-pyrimidine (HPP), and 4-mercapto pyrazolo-pyrimidine (MPP) on copper in 0.5M
H2SO4 solution have been investigated using electrochemical, surface analysis, as well as theoretical techniques.
The results indicate that these inhibitors have largely inhibited the corrosion of copper and the inhibition efficiency
increased with increasing concentration. Moreover, the inhibitors adsorb on copper surface following
Langmuir adsorption isotherm. XPS analysis were performed for describing the bonding characteristics between
inhibitors and copper substrate. Furthermore, DFT and molecular dynamics simulation calculations were applied
to further explain the anti-corrosion mechanism.
Corrosion Inhibition of Mild Steel in HCl Medium by a Condensation Productijtsrd
A condensation product CP was successfully synthesized from reaction of dimethyl amino benzaldehyde and aniline giving yields of 80 . The compound was characterized by Fourier Transform Infrared FTIR Spectroscopy. The corrosion inhibiting property of the CP on mild steel in HCl solution were investigated by the weight loss measurements, electrochemical impedance spectroscopy EIS and linear polarization resistance LPR . The concentrations of CP were varied from 1 x 10 3 M to 5 x 10 3 M. The inhibition efficiencies obtained from all the methods employed were in good agreement where the percentage of inhibition efficiencies increased with concentration of CP. Results showed that CP was the better inhibitor with inhibition efficiency of 90 at 5 x 10 3 M additive concentration. This is likely due to the effect of its large molecular size, higher number of electroactive heteroatoms and bigger p electron cloud of the conjugated double bond system. Ganesha Achary "Corrosion Inhibition of Mild Steel in HCl Medium by a Condensation Product" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-4 , June 2020, URL: https://www.ijtsrd.com/papers/ijtsrd30869.pdf Paper Url :https://www.ijtsrd.com/chemistry/physical-chemistry/30869/corrosion-inhibition-of-mild-steel-in-hcl-medium-by-a-condensation-product/ganesha-achary
Some factors affecting on the behavior ofsteel electrode in citric acid solut...IJERA Editor
Potential-time curves are constructed for the steel electrode in naturally aerated citric acid solutions devoid of
and containing some aggressive and inhibitive compounds. Cl- and SO4
2- ions cause the destruction of passivity
and initiation of pitting corrosion. The rate of oxide film growth by citric acid and oxide film destruction by Cl-
and SO4
2- ions follows a direct logarithmic law as evident from the linear relationships between the open-circuit
potential and the logarithm of immersion time. Urea, phenylhydrazine and 1,2-phenylenediamine compounds
inhibit the pitting corrosion of steel. The rate of oxide film healing and thickening increases with their
concentrations. In presence of constant inhibitor concentration, the efficiency of pitting inhibition increases in
the order: (weak) urea<phenylhydrazine><1,2-phenylenediamine(strong).
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The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Thermodynamic characterization of metal dissolution and inhibitor adsorption ...IJRES Journal
The inhibition effect of 1-hexyl-3-methylimidazolium chloride (HMIC) on the corrosion of mild
steel in 2M sulphuric acid solution has been investigated by weight loss. potentiodynamic polarization and
electrochemical impedance spectroscopy. The effect of temperature on the corrosion behavior of mild steel in
2M H2SO4 with addition of inhibitor was studied in weight loss method at the temperature range of 308-328 K.
Results obtained that the inhibition efficiency increases with increasing the concentration of the inhibitor and
decreases with increasing the temperature. Polarization and impedance measurements were in good agreement.
The adsorption of this inhibitor on the mild steel surface obeys the Langmuir adsorption isotherm. Fourier
transform spectroscopy (FTIR) and Scanning electron microscopy (SEM) was also carried out to establish the
corrosion inhibit property of this inhibitor in sulphuric acid medium. Quantum chemical calculations were
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the inhibitor and the electronic properties of its main constituents.
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Corrosion inhibition nature of a synthesized Schiff’s base was studied on the corrosion of mild steel in 1.0 M HCl using weight loss and electrochemical methods. The results indicated that the synthesized Schiff base is an effective inhibitor in reducing the corrosion of mild steel in 1.0 M HCl solution. The inhibitor efficiency of inhibitor increased with inhibitor concentration and showed maximum inhibition efficiency at 300 ppm concentration. The adsorption of inhibitor molecules on to the metal surface obeyed Langmuir Adsorption isotherm. The adsorption mechanism involved both physical and chemical adsorptions. The potentiodynamic polarization studies showed that the inhibitor is a mixed typed inhibitor with more cathodic nature. Potential of zero charge was also determined and the adsorption mechanism discussed. Quantum mechanical studies showed that the Schiff base molecules have the strong tendency to donate electron pairs to the metallic atoms on the surface
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organic Inhibitor (Methyl Orange), the organic inhibitor (Methyl Red), the green inhibitor (Terminalia Catappa Leaves)
and green inhibitor (Carica Papaya Leaves) produced their best inhibition efficiency of 71.94%, 634%, 68.94%, 68.32%,
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Corrosion inhibition of heat treated mild steel with neem leave extract in a ...eSAT Journals
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1. ORIGINAL ARTICLE
Apricot juice as green corrosion inhibitor of mild steel
in phosphoric acid
Aprael S. Yaro a
, Anees A. Khadom b,*, Rafal K. Wael a
a
Chemical Engineering Department, College of Engineering, University of Baghdad, Aljadrea, Baghdad, Iraq
b
Chemical Engineering Department, College of Engineering, University of Daiyla, Baquba, Iraq
Received 16 May 2011; revised 10 May 2012; accepted 7 November 2012
Available online 11 December 2012
KEYWORDS
Corrosion;
Mild steel;
Kinetic parameters;
Green corrosion inhibitor;
Statistical analysis
Abstract The corrosion protection of mild steel in 1 M H3PO4 solution by apricot juice was stud-
ied at different temperatures by weight loss technique. Adsorption, activation and statistical studies
were addressed in this work. Adsorption studies showed that inhibitor adsorbed on metal surface
according to Langmuir isotherm. Average value of heat of adsorption was À14.93 kJ/mol indicates
a spontaneous physical adsorption on metal surface. Activation parameters did not changed with
addition of inhibitor indicates that there is no change in reaction mechanism. Analysis of variance
(ANOVA) was also applied. This analysis showed that the corrosion rate influenced by tempera-
ture, inhibitor concentration and combined interaction of them.
ª 2013 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V.
All rights reserved.
1. Introduction
Many metals and alloys which used in different human activities
are susceptible to different mechanisms of corrosion due to their
exposure to different corrosive media. Among these, mild steel is
very important. One of the methods used to reduce the rate of
metallic corrosion is addition of inhibitors. Many studies have
been carried out to find suitable compounds to be used as corro-
sion inhibitors for this metal in different aqueous solutions.
These studies reported that there are a number of organic and
inorganic compounds which can inhibit corrosion of steel [1–
3]. Many researchers were conducted to examine some naturally
occurring substances as corrosion inhibitors for different metals
in various environments [4,5]. Naturally occurring molecules
exhibiting a strong affinity for metal surfaces are the focus of re-
search oriented toward the development of environmentally
friendly corrosion inhibitors; compounds showing good inhibi-
tion efficiency and low environmental risk. Among the so-called
‘‘green corrosion inhibitors’’ are organic compounds that act by
adsorption on the metal surface, such as ascorbic acid [6], succi-
nic acid [7], tryptamine [8], caffeine [9] and extracts of natural
substances [10–14]. The efficiency of these organic corrosion
inhibitors is related to the presence of polar functional groups
with S, O or N atoms in the molecule, heterocyclic compounds
and pi electrons. The polar function is usually regarded as the
reaction center for the establishment of the adsorption process
* Corresponding author. Mobile: +964 790 2305786.
E-mail address: aneesdr@gmail.com (A.A. Khadom).
Peer review under responsibility of Faculty of Engineering, Alexandria
University.
Production and hosting by Elsevier
Alexandria Engineering Journal (2013) 52, 129–135
Alexandria University
Alexandria Engineering Journal
www.elsevier.com/locate/aej
www.sciencedirect.com
1110-0168 ª 2013 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.aej.2012.11.001
2. [15]. One of these natural compounds is fruits. Fruit is a rich
source of chemicals such as vitamins, minerals, and phenolic
compounds. The apricot juice includes different level of pheno-
lic compounds. The hydroxycinnammic acids, such as caffiec, b-
coumaric and ferulic acids and their esters are the most common
compounds in apricot fruits [16]. Therefore, the aim of the pres-
ent work is to investigate the inhibition action of apricot juice for
the corrosion of mild steel in order to find a naturally occurring,
cheap and environmentally safe substance that could be used for
inhibition purposes.
2. Experimental work
Fully ripened apricots were purchased from a local market
(Baghdad – Iraq). The fruits were washed in cold tap water
and then mechanically compressed to obtain corresponding
juice. The juice was then filtered to obtain a homogenous solu-
tion. In this process, one liter of apricots juice was obtained
from 3 kg fresh fruit. The extracted juice was kept frozen
(>0 °C) in glass bottles until further experiment. The concen-
trations of inhibitor were closer as 10, 20, 30, and 40 g/l. Rect-
angular mild steel specimens with dimensions of 3 · 1 · 0.1 cm
were used as the working electrodes throughout the study. The
composition (wt.%) of the mild steel was: Fe, 98.9; C, 0.199;
Si, 0.124; Mn, 0.053; Al, 0.0514; Cr, 0.009; Cu, 0.0468; Ti,
0.0089; V, 0.0076; Ni, 0.00352; Co, 0.0091; Mo, 0.005; Pb,
0.05, it was analyzed at Specialized Institute of Engineering
Industries – Baghdad – Iraq. The cleaning procedure was as
follows: The specimens were first degreased with analar ben-
zene and acetone, and then annealed in a vacuum oven at
600 °C for 1 h and cooled to room temperature. Samples were
abraded in sequence under running tap water using emery pa-
per of grade numbers 220, 320, 400 and 600, washed with run-
ning tap water followed by distilled water, dried with clean
tissue, immersed in acetone and benzene, and kept in desicca-
tors over silica gel bed until time of use. The specimens were
fully immersed for 2 h in 250 cm3
corrosive solution at 1 M
H3PO4, 30, 40, 50, 60 °C, and 10, 20, 30, 40 g/l apricot juice
concentration. After each experiment the specimens were
washed with running tap water followed by distilled water,
dried with clean tissue, immersed in acetone and benzene,
and kept in desiccators over silica gel bed to dry, then weighed
by high accuracy electronic balance. To test reliability and
reproducibility of the measurements, duplicate experiments
were performed in each case of the same conditions.
3. Results and discussion
The corrosion of mild steel in 1 M H3PO4 solution containing
various concentrations of inhibitor at different temperatures
was studied by weight loss measurements. The corrosion rate
of mild steel was determined using the relation:
W ¼
Dm
S Â t
ð1Þ
where Dm is the mass loss (g), S the area (m2
) and t is the
immersion period (day). The percentage inhibition efficiency
(IE(%)) was calculated using the relationship [17]:
IE% ¼
Wuninibit À Winhibit
Wuninhibit
 100 ð2Þ
where Wuninhibit and Winhibit are the corrosion rates in absence
and presence of inhibitor respectively. Table 1 shows the
variation of corrosion rates and inhibitor efficiency with inhib-
itor concentration and temperature. It is clear that at certain
experimental temperature, corrosion rate of steel decreases
with an increase in concentration of inhibitor. In absence
and presence of a certain concentration of inhibitor, the corro-
sion rate of steel increases with rise in temperature, obeying the
Arrhenius type reactions which will be discussed later. It was
reported that the rate of iron corrosion in acid solutions is
approximately doubles for every 10 °C rise in temperature
[18]. Values of inhibitor efficiency increase with increasing
inhibitor concentration.
3.1. Adsorption studies and inhibition mechanism
The primary step in the action of inhibitors in acid solution is
generally agreed to be adsorption on the metal surface. This in-
volves the assumption that the corrosion reactions are pre-
vented from occurring over the area (or active sites) of the
metal surface covered by adsorbed inhibitor species, whereas
these corrosion reaction occurred normally on the inhibitor-
free area [19]. Accordingly, the fraction of surface covered with
inhibitor species ðh ¼ IE%
100
Þ can followed as a function of inhib-
itor concentration and solution temperature. The surface cov-
erage (h) data are very useful while discussing the adsorption
characteristics. When the fraction of surface covered is deter-
mined as a function of the concentration at constant tempera-
ture, adsorption isotherm could be evaluated at equilibrium
condition. The dependence of the fraction of the surface cov-
ered h on the concentration C of the inhibitor was tested
graphically by fitting it to Langmuir’s isotherm, which assume
that the solid surface contains a fixed number of adsorption
sites and each site holds one adsorbed species. Fig. 1 show
the linear plots for C/h versus C with R2
= 0.9979 correlation
coefficient, suggestion that the adsorption obeys the Lang-
muir’s isotherm:
Table 1 Corrosion rates data of mild steel in 1 M H3PO4 in
absence and presence of different concentrations of apricots
juice.
Run
number
Inhibitor
concentration
(g/l)
Temperature
(°C)
Corrosion
rates
(g mÀ2
dayÀ1
)
Inhibitor
efficiency
(%)
1 Nil 30 255.77
2 40 449.3
3 50 783.0
4 60 1324.8
5 10 30 96 63
6 40 210.45 53
7 50 266.24 66
8 60 508.29 62
9 20 30 83.22 68
10 40 168.96 62
11 50 243.86 69
12 60 450.1 66
13 30 30 76.73 70
14 40 155.1 66
15 50 229.48 71
16 60 410.69 69
17 40 30 64.1 75
18 40 150.63 67
19 50 211.83 73
20 60 378.14 72
130 A.S. Yaro et al.
3. C
h
¼
1
K
þ C ð3Þ
where C is the equilibrium inhibitor concentration, K
adsorptive equilibrium constant, representing the degree of
adsorption (i.e., the higher the value of K indicates that the
inhibitor is strongly adsorbed on the metal surface), the aver-
age value of K was 0.296 l/g which obtained from the recipro-
cal of intercept of Langmuir plot line, and the slop of this line
is near unity meaning that each inhibitor molecules occupies
one active site on the metal surface.
The standard adsorption free energy ðDGo
adsÞ was calculated
using the following equation [20]:
K ¼
1
999
exp À
DGo
ads
RT
ð4Þ
where 999 are the concentration of water in solution expressed
in g/l, R is gas constant, and T absolute temperature. The
average value of standard adsorption free energy (DGo
ads) was
À14.93 kJ/mol. The negative value of DGo
ads ensure the sponta-
neity of the adsorption process and stability of the adsorbed
layer on the metal surface. Generally, value of DGo
ads up to
À20 kJ molÀ1
is consistent with electrostatic interaction
between the charged molecules and the charged metal (physi-
sorption) while those around À40 kJ molÀ1
or higher are asso-
ciated with chemisorptions as a result of sharing or transfer of
electrons from the molecules to the metal surface to form a
coordinate type of bond [20]. While other researchers sug-
gested that the range of DGo
ads of chemical adsorption processes
for inhibitor in aqueous media lies between À21 and
À42 kJ molÀ1
[1]. Therefore, for present work the values of
DGo
ads has been considered within the range of physical adsorp-
tion. It was observed from Table 2, limited increase in the
absolute value of DGo
ads at 50 °C temperature, then, heat of
adsorption decreased again at 60 °C indicating that the
adsorption was somewhat favorable at this experimental tem-
perature and apricot juice adsorbed according to physical
mechanism, i.e. desorption of inhibitor molecules when tem-
perature increased. Moreover, the essential characteristic
Langmuir isotherm can be expressed in term of a dimension-
less separation factor, RL [1], which describe the type of iso-
therm and defined by:
RL ¼
1
1 þ KC
ð5Þ
The smaller RL value indicates a highly favorable adsorption.
If RL 1 unfavorable, RL = 1 linear, 0 RL 1 favorable,
and if RL = 0 irreversible. Table 3 gives the estimated values of
RL for apricot juice at different concentrations. It was found
that all RL values are less than unity conforming that the
adsorption processes is favorable.
Recent researches have looked into the action of an adsorp-
tive inhibitor from a purely mechanistic kinetic point of view
[1]. This relation can be expressed as follow:
h
1 À h
¼ K0
Cy
ð6Þ
5 10 15 20 25 30 35 40 45
C (g/l)
10
15
20
25
30
35
40
45
50
55
60
65
30 o
C
40
50
60
Figure 1 Langmuir adsorption isotherm for apricot juice on mild steel.
Table 2 Langmuir adsorption constants and change in free energy at different temperatures.
Temperature (°C) KLangmuir (l/g) Slop DGo
ads (kJ/mol) KKinetic (l/g) y
30 0.255 1.09 À13.96 0.389 0.38
40 0.195 1.20 À13.72 0.141 0.44
50 0.446 1.10 À16.38 1.613 0.23
60 0.286 1.08 À15.66 0.438 0.32
Average value 0.296 1.11 À14.93 0.645 0.343
Apricot juice as green corrosion inhibitor of mild steel in phosphoric acid 131
4. or this equation can be writing in linear form as;
ln
h
1 À h
¼ ln K0
þ y ln C ð7Þ
where K0
is a constant, and y is the number of inhibitor mole-
cules occupying one active site. A plot of lnð h
1Àh
Þ versus lnC
gives a straight line of slop y and intercept of lnK0
, as shown
in Fig. 2. Equilibrium constant corresponding to adsorption
isotherm is given by, K ¼ K01
y. Values of y 1 implies the
formation of multilayer of inhibitor on the surface of metal.
Values of y 1 mean a given inhibitor molecules will occupy
more than one active site. The behavior of equilibrium
constants obtained from Langmuir model was similar to the
values which obtained by kinetic–thermodynamic model. Also
the values of y were lower than unity indicating the formation
of monolayer on the metal surface which agree the assump-
tions of Langmuir adsorption isotherm.
3.2. Effect of inhibitor concentration on activation parameters
The mechanism of the inhibitor action can be deduced by
comparing the apparent activation energies, Ea, in the presence
and absence of the corrosion inhibitor. Activation parameters
such as Ea, the enthalpy of activation, DHa, and the entropy of
activation, DSa, for both corrosion and corrosion inhibition of
mild steel in 1 M H3PO4 in the absence and presence of various
concentrations of peach juice in the range of studied tempera-
tures (30–60 °C) were calculated from an Arrhenius-type plot
(Eq. (8)) and transition-state (Eq. (9)) [21], respectively:
W ¼ A exp À
Ea
RT
ð8Þ
where W is the corrosion rate, A is the Arrhenius constant, Ea
is the apparent activation energy, and R is the universal gas
constant.
W ¼
RT
Nh
exp
DSa
R
exp À
DHa
RT
ð9Þ
where N is Avogadro’s constant, h is Planck’s constant, DSa is
the change of entropy for activation, and DHa is the change of
enthalpy for activation. As shown in Figs. 3 and 4, plots of
ln(W) versus 1/T and ln(W/T) versus 1/T give straight lines
with slopes of DEa/R and DHa/R, respectively. The intercepts,
which can then be calculated, will be ln(A) and [ln(R/
Nh) + (DSa/R)] for the Arrhenius and transition-state equa-
tions, respectively. Table 4 collects the activation parameters
for mild steel corrosion reaction in H3PO4. The results showed
positive sign for both Ea and DHa, reflecting the endothermic
nature of corrosion process. The values of Ea and DHa varies
in the same way, it is obviously seen that the activation energy
increased slightly in the presence of inhibitor. This indicating
that the corrosion reaction of mild steel is inhibited by apricot
juice, hence supports the phenomenon of physical adsorption.
The increase in the activation energy in the presence of the
additives signifies physical adsorption. The negative values of
DSa pointed to a greater order produced during the process
of activation. This can be achieved by the formation of
activated complex represents association or fixation with con-
sequent loss in the degrees of freedom of the system during the
process [22].
3.3. Statistical and mathematical analysis
The experimental corrosion rate results in uninhibited and
inhibited 1 M H3PO4 acid as a function of temperature and
inhibitor concentration are given in Table 1. This table was
rearranged as shown in Table 5 in matrix array. Matrix array
may be helpful for statistical analysis. The statistical technique
known as analysis of variance (ANOVA) can be used. This
technique based on variance ratios to determine whether or
Table 3 The values of dimensionless separation factor
RL for apricot juice at various conditions.
Inhibitor concentration (g/l) RL
30 40 50 60 °C
10 0.281 0.339 0.183 0.259
20 0.164 0.204 0.101 0.149
30 0.116 0.146 0.069 0.104
40 0.089 0.114 0.053 0.081
2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8
ln C
0.0
0.2
0.4
0.6
0.8
1.0
1.2
30 0C
40
50
60
Figure 2 Kinetic–thermodynamic model for the adsorption of apricot juice on mild steel surface.
132 A.S. Yaro et al.
5. not significant differences exist among the means of several
groups of observation. Two-way ANOVA has been used in
order to determine the effect of temperature and inhibitor
concentration on corrosion rate. This will be done by deter-
mine whether variation in the column variable Xj (tempera-
ture) affects the column means and row variable Xi
(inhibitor concentration) affects the row means. Calculation
formulas were shown in Table 6. The hypothesis would be re-
jected if the computed F values (F), is too large. That is the
rejection region is of the form [23]:
F FK1;K2;ð1ÀaÞ ð10Þ
where K1 = j À 1, K2 = ji for column, K1 = i À 1, K2 = ij for
rows, and a is significant level (0.05). Numerical values of
Table 6 were shown in Table 7. Inspection of Table 7 shows that
we reject the hypothesis of no effect of column variable or the
row variable. The results clearly show that temperature and
inhibitor concentration at 95% confidence level respectively
0.00295 0.00300 0.00305 0.00310 0.00315 0.00320 0.00325 0.00330 0.00335
1/T (K-1)
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
lnW(g.m-2
.day-1
)
Nil
10 g/l
20
30
40
Figure 3 Arrhenius plot for the corrosion of mild steel in 1 M H3PO4.
0.00295 0.00300 0.00305 0.00310 0.00315 0.00320 0.00325 0.00330 0.00335
1/T (K-1)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
lnW/T(g.K-1
.m-2
.day-1
)
Nil
10 g/l
20
30
40
Figure 4 Transition state plot for the corrosion of mild steel in 1 M H3PO4.
Table 4 Activation parameters for mild steel corrosion
reaction in H3PO4.
C (g/l) Ea (kJ/mol) DHa (kJ/mol) DSa (kJ/mol K)
0 42.02 43.38 À0.053
10 43.95 41.33 À0.071
20 45.55 42.94 À0.067
30 45.45 42.90 À0.068
40 47.56 45.00 À0.062
Average value 45.706 43.11 À0.064
Apricot juice as green corrosion inhibitor of mild steel in phosphoric acid 133
6. have a significant effect on corrosion rate. It also clear that there
is an interaction between temperature and inhibitor concentra-
tion factors. According to these results, second order polyno-
mial model was used to represent these variables. This model
takes into account the effect of temperature, inhibitor concen-
tration, and the interaction of them on corrosion rate:
W ¼ Bo þ B1T þ B2T2
þ B3TC þ B4C þ B5C2
ð11Þ
Table 5 Matrix array of corrosion rate as a function of temperature and inhibitor concentration.
C (g/l) Temperature (°C)
30 40 50 60
0 255.77 449.3 783 1324.8 X1 = 2812.87
10 96 210.45 266.24 508.29 X2 = 1080.98
20 83.22 168.96 243.86 450.1 X3 = 946.140
30 76.73 155.1 229.48 410.69 X4 = 872.000
40 64.1 150.36 211.83 378.14 X5 = 804.430
X1 = 575.82 X2 = 1134.17 X3 = 1734.41 X4 = 3072.02 X = 6516.40
Table 6 Formulas of two-way ANOVA with interactions.
Source of variation Degrees of freedom (f) Sum of squares (SS) Mean squares (MS) Test statistic (F)
Between columns j À 1
SSC ¼
P
j
X2
ÅjÅ
ik À
X2
ÅÅÅ
ijk
MSC ¼ SSC
jÀ1 F ¼ MSC
MSE
Between rows i À 1
SSR ¼
P
i
X2
iÅÅ
jk À
X2
ÅÅÅ
ijk
MSR ¼ SSR
iÀ1 F ¼ MSR
MSE
Interaction columns-rows (j À 1) (i À 1)
SSCR ¼
P
i
P
j
X2
ijÅ
k À
P
i
X2
iÅÅ
jk À
P
j
X2
ÅjÅ
ik þ
X2
ÅÅÅ
ijk
MSCR ¼ SSCR
ðiÀ1ÞðjÀ1Þ F ¼ MSCR
MSE
Error ij (k À 1) SSE ¼ SST À SSC À SSR À SSCR MSE ¼ SSE
ðiÀ1ÞðjÀ1Þ –
Total ijk À 1 SST ¼
P
i
P
j
P
kX2
ijk À
X2
ÅÅÅ
ijk
– –
Table 7 Numerical values of two-way ANOVA with interactions.
Source of variation f SS MS F Ftable
Between columns 3 929,050 309,683 3.597 F3;20;0:95 ¼ 3:1
Between rows 4 1,076,280 269,070 3.041 F4;20;0:95 ¼ 2:87
Interaction columns-rows 12 3,006,936 250,578 2.832 F12;20;0:95 ¼ 2:29
Error 20 1,061,776 88,481 –
Total 39 6,720,095 – –
0 200 400 600 800 1000 1200 1400
experimental corrosion rate (g.m-2
.day-1
)
0
200
400
600
800
1000
1200
predictedcorrosionrate(g.m-2
.day-1
)
Y=35.8+0.9X
Figure 5 Predicted corrosion rate versus experimental corrosion rate.
134 A.S. Yaro et al.
7. Nonlinear least squares regression analysis based on Leven-
berg–Marquardt estimation method can be used for estimation
of coefficients Bo, B1,. . .,B5, producing the following equation
with 0.944 correlation coefficient:
W ¼ 194:0161 À 8:2947T þ 0:3895T2
À 0:5291TC
À 10:9657C þ 0:6053C2
ð12Þ
where W, T and C are corrosion rate (g mÀ2
dayÀ1
), tempera-
ture (°C), and inhibitor concentration (cm3
/l) respectively.
Fig. 5 shows predicted corrosion rate by Eq. (12) against
experimental one.
4. Conclusion
Apricot juice acts as a corrosion inhibitor of mild steel with
maximum inhibition efficiency of 75% at 30 °C and maximum
level of inhibitor concentration. Adsorption of inhibitor obeys
Langmuir adsorption isotherm by forming a monolayer on
metal surface, this result was confirmed by application of ther-
mo-dynamic adsorption model. Values of heat of adsorption
were low indicating a physical adsorption on metal surface. Sta-
tistical analysis shows that corrosion rate influenced by temper-
ature, inhibitor concentration and the combined effect of them.
Acknowledgment
This work was supported by Baghdad University, Chemical
Engineering Department, which is gratefully acknowledged.
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