Corrosion inhibition of mild steel in acidic medium using hydrazide derivatives

The corrosion inhibition characteristics of N′-[(1E)-(4-hydroxy phenyl) methylene] isonicotinohydrazide (HIH) & N′-[(1E)-(4-hydroxyl-3-methoxy phenyl) methylene] isonicotinohydrazide (HMIH) on mild steel corrosion in 1 M hydrochloric acid were investigated by weight loss, potentiodynamic polarization and impedance techniques. The inhibition efficiency increased with increase in inhibitor concentration but decreased with increase in temperature. The thermodynamic functions of dissolution and adsorption processes were evaluated. The polarization measurements indicated that the inhibitors are of mixed type. The adsorption of the compounds was found to obey Langmuir’s adsorption isotherm. Passive film characterization was done by Fourier transform infrared (FTIR) spectra and scanning electron microscopy (SEM).     

Investigation of some oleochemicals as green inhibitors on mild steel corrosion in sulfuric acid

The inhibitive effect of four oleo chemicals (namely; 2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI)), regarded as green inhibitors, were studied for the corrosion protection of mild steel in 0.5 M H₂SO₄. The methods employed were weight loss, potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopy (SEM) was carried out on the inhibited and uninhibited metal samples to characterize the surface. The purity of synthesized inhibitors was checked by FT-IR and NMR studies. The inhibition efficiency increased with increase in inhibitor concentration, immersion time and decreased with increase in solution temperature. No significant change in IE values was observed with increase in acid concentration. The best performance was obtained for UDI possessing 96.2% inhibition efficiency at 500 ppm concentration. The adsorption of the compounds on the mild steel surface in the presence of sulfuric acid obeyed Langmuir’s adsorption isotherm. The values obtained for free energy of adsorption and heats of adsorption suggest physical adsorption. The addition of inhibitor decreased the entropy of activation suggesting that the inhibitors are more orderly arranged along the mild steel surface. The potentiodynamic polarization data indicate mixed control. The electrochemical impedance study further confirms the formation of a protective layer on the mild steel surface through the inhibitor adsorption.     

Inhibition of mild steel corrosion in the presence of fatty acid triazoles

The influence of some fatty acid triazoles namely, 4-Phenyl-5-undecyl-4H- [1,2,4] triazole-3-thiol (PUTT), 5-Heptadec-8-enyl-4-phenyl-4H- [1,2,4] triazole-3-thiol (HPTT), and 5-Dec-9-enyl-4-phenyl-4H- [1,2,4] triazole-3-thiol (DPTT) on the corrosion of mild steel in 1 M hydrochloric acid (HCl) and 0.5 M sulfuric acid (H₂SO₄) was studied by weight loss and potentiodynamic polarization methods. The values of activation energy and free energy of adsorption of all the triazoles were calculated to investigate the mechanism of corrosion inhibition. The potentiodynamic polarization studies were carried out at room temperature, according to which all the compounds were mixed type inhibitors and inhibit the corrosion of mild steel by blocking the active sites of the metal. The adsorption of all the triazoles on mild steel surface in both the acid solutions was found to obey the Langmuir adsorption isotherm. All the compounds showed good inhibition efficiency in both acids. The inhibition efficiency of the compounds was found to vary with their nature and concentration, solution temperature and immersion time. Electrochemical impedance spectroscopy was also used to investigate the mechanism of the corrosion inhibition.     

THE EFFECT OF ENVIRONMENTALLY BENIGN FRUIT EXTRACT OF SHAHJAN (MORINGA OLEIFERA) ON THE CORROSION OF MILD STEEL IN HYDROCHLORIC ACID SOLUTION

The inhibition of the corrosion of mild steel in hydrochloric acid solution by the fruit extract of shahjan (Moringa oleifera) was studied using weight loss, electrochemical impedance spectroscopy (EIS), linear polarization, and potentiodynamic polarization techniques (Tafel). Inhibition was found to increase with increasing concentration of the extract. The effect of temperature, immersion time, and acid concentration on the corrosion behavior of mild steel in hydrochloric acid solutions with addition of extract was also studied. The inhibition occurred via adsorption of the inhibitor molecules on the mild steel surface obeying the Langmuir adsorption isotherm. Thermodynamic activation parameters such as activation energy, enthalpy (ΔH*), and entropy (ΔS*) of activation for corrosion process were calculated and discussed. The results obtained show that both chemical and physical adsorption of inhibitor molecules occur simultaneously and the fruit extract of shahjan (Moringa oleifera) could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid media.     

Synergistic inhibition between the gemini surfactant and bromide ion for steel corrosion in sulphuric acid

The inhibitive synergistic effect between a cationic gemini surfactant, 1,3-propane-bis(dimethyl dodecylammonium bromide) (12-3-12), and bromide ion for the corrosion inhibition of cold rolled steel in 0.5 mol L⁻¹ H₂SO₄ was investigated by weight loss, potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The inhibition system composed by 12-3-12 and bromide ion is efficient. The adsorption mechanism of the 12-3-12 and bromide ion on steel in acidic medium is discussed on the basis of experimental data and an adsorption model is proposed. Adsorption of inhibitor system on the mild steel surface in acidic medium obeys Langmuir’s adsorption isotherm. In addition, potentiodynamic polarization studies show that the system acts as a mixed-type inhibitor. Electrochemical impedance spectroscopy also suggests the formation of a protective layer on the steel surface by the adsorption of surfactant molecules and bromide ions.     

Influence of substituted benzothiazoles on corrosion in acid solution

Compounds such as 2-aminobenzothiazole (ABT), 2-amino-6-chlorobenzothiazole (ACLBT), 2-amino-6-methyl benzothiazole (AMEBT) and 2-amino-6-methoxy benzothiazole (AMEOBT) have been synthesized and their inhibitive action on the corrosion of mild steel in 1 m HCl has been evaluated using weight loss, potentiodynamic polarization studies and hydrogen permeation measurements. Determination of inhibition efficiency in the presence of these compounds at different temperatures clearly indicates that ACLBT shows the best performance, even at a temperature as high as 60°C. Potentiodynamic polarization studies reveal the fact that ABT and its derivatives act as cathodic inhibitors. All these compounds are found to reduce the permeation of hydrogen through mild steel in HCl solution. The adsorption of these compounds on mild steel from HCl solutions obeys Temkin's adsorption isotherm. The adsorption of 2-amino benzothiazole on the mild steel has been substantiated by Auger electron spectroscopy.     

Extraction and experimental studies of Citrus aurantifolia as an economical and green corrosion inhibitor for mild steel in acidic media

The Citrus aurantifolia leaves extract was tested for corrosion inhibition on the mild steel in a 0.5?M sulfuric acid solution using weight loss, Tafel and EIS. The state of mixed adsorption with the potentiodynamic polarization effect is shown. Citrus aurantifolia showed the strongest corrosion inhibition of 96.46% at a concentration of 250?mg/L. SEM and AFM are used to verify the formation of a protective layer on the surface of mild steel. The adsorption phenomenon was verified using UV-Vis. spectroscopic technique, whereas FT-IR confirmed the presence of several functional groups containing heteroatoms. Adsorption of the inhibitory molecules on the mild steel surface followed the Langmuir adsorption isotherm. All obtained results ensure that C. aurantifolia leaves extract can form an effective blocking layer and control the corrosion process.     

Fatty acid oxadiazoles as corrosion inhibitors for mild steel in formic acid

Selected oxadiazoles of fatty acids; namely 2-hepta decene-5-mercapto-1-oxa-3,4-diazole (HMOD); 2-undecane-5-mercapto-1-oxa-3,4-diazole (UMOD); and 2-decene-5-mercapto-1-oxa-3,4-diazole (DMOD), were synthesized. Their influence on the inhibition of corrosion of mild steel in 20% formic acid (HCOOH) was investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency of the compounds was found to vary with concentration, immersion time and temperature. All the compounds showed good inhibition efficiency (e _IE) in formic acid solution. Adsorption on mild steel obeyed the Langmuir adsorption isotherm. Potentiodynamic polarization revealed that all three inhibitors, HMOD, UMOD, and DMOD are mixed inhibitors. Electrochemical impedance spectroscopy was also used to investigate the inhibition mechanism.     

Corrosion inhibition by fatty acid triazoles for mild steel in formic acid

5-Heptadec-8-enyl-4-phenyl-4H–[1,2,4] triazole-3-thiol (HPTT), 4-phenyl-5-undecyl-4H–[1,2,4] triazole-3-thiol (PUTT), and 5-dec-9-enyl-4-phenyl-4H–[1,2,4] triazole-3-thiol (DPTT) were synthesized and their influence on the inhibition of corrosion of mild steel in 20% formic acid was investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency of these compounds was found to vary with their nature and concentration, temperature and immersion time. The values of activation energy and free energy of adsorption of the triazoles were calculated to investigate the mechanism of corrosion inhibition. Good inhibition efficiency (>90%) was found even at lower concentration (i.e., 25 ppm) in acid solution. The adsorption on mild steel surfaces was found to obey Temkin's adsorption isotherm. Potentiodynamic polarization results revealed that the compounds studied are mixed type inhibitors. Electrochemical impedance spectroscopy was also used to investigate the mechanism of the corrosion inhibition.     

Inhibition Effects of a Synthesized Novel 4-Aminoantipyrine Derivative on the Corrosion of Mild Steel in Hydrochloric Acid Solution together with Quantum Chemical Studies

1,5-Dimethyl-4-((2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-one (DMPO) was synthesized to be evaluated as a corrosion inhibitor. The corrosion inhibitory effects of DMPO on mild steel in 1.0 M HCl were investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, open circuit potential (OCP) and electrochemical frequency modulation (EFM). The results showed that DMPO inhibited mild steel corrosion in acid solution and indicated that the inhibition efficiency increased with increasing inhibitor concentration. Changes in the impedance parameters suggested an adsorption of DMPO onto the mild steel surface, leading to the formation of protective films. The novel synthesized corrosion inhibitor was characterized using UV-Vis, FT-IR and NMR spectral analyses. Electronic properties such as highest occupied molecular orbital energy, lowest unoccupied molecular orbital energy (EHOMO and ELUMO, respectively) and dipole moment (μ) were calculated and discussed. The results showed that the corrosion inhibition efficiency increased with an increase in the EHOMO values but with a decrease in the ELUMO value.     

Inhibition of mild steel corrosion in sulfuric acid solution by thiadiazoles

Four heterocyclic compounds namely 2-amino-1,3,4-thiadiazoles (AT), 5-Methyl-2-amino-1,3,4-thiadiazoles (MAT), 5-Ethyl-2-amino-1,3,4-thiadiazoles (EAT) and 5-Propyl-2-amino-1,3,4-thiadiazoles (PAT) were synthesized and their influence on the inhibition of corrosion of mild steel (MS) in 0.5 M H₂S0₄ was investigated by weight loss and potentiodynamic polarization techniques. The values of activation energy, free energy of adsorption, heat of adsorption, enthalpy of activation and entropy of activation were also calculated to investigate the mechanism of corrosion inhibition. Potentiodynamic polarization studies were carried out at room temperature, and showed that all the compounds studied are mixed type inhibitors causing blocking of active sites on the metal. The inhibition efficiency of the compounds was found to vary with concentration, temperature and immersion time. Good inhibition efficiency was evidenced in the sulfuric acid solution. The adsorption of the compounds on mild steel for sulfuric acid was found to obey Langmuir’s adsorption isotherm. FT–IR spectroscopic studies were also used to investigate the purity of compounds synthesized.     

Adsorption and corrosion inhibition behaviour of N-(phenylcarbamothioyl)benzamide on mild steel in acidic medium

Corrosion inhibition property of N-(phenylcarbamothioyl)benzamide (PCB) on mild steel in 1.0 M HCl solution has been investigated using chemical (weight loss method) and electrochemical techniques (potentiodynamic polarization and AC impedance spectroscopy). The inhibition efficiencies obtained from all the methods are in good agreement. The thiourea derivative is found to inhibit both anodic and cathodic corrosion as evaluated by electrochemical studies. The inhibitor is adsorbed on the mild steel surface according to Langmuir adsorption isotherm. The adsorption mechanism of inhibition was supported by spectroscopic (UV-visible, FT-IR, XPS), and surface analysis (SEM-EDS) and adsorption isotherms. The thermodynamic parameter values of free energy of adsorption (ΔG_ads) reveals that inhibitor was adsorbed on the mild steel surface via both physisorption and chemisorption mechanism.     

In depth analysis of anti corrosion behaviour of eco friendly gum exudate for mild steel in sulphuric acid medium

The current research work was keen to examine the corrosion inhibition efficiency of mild steel (MS) in presence of aqueous extract of Araucaria heterophylla Gum (AHG) in 1?M H₂SO₄ medium. The phytoconstituents of the AHG were interpreted by GC-MS and corrosion inhibition efficiency was deduced using other techniques like weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Adsorption of inhibitor molecules on the mild steel surface was supported by Density Functional Theory (DFT) studies, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). It is seen from the results that the inhibitor exhibits optimum efficiency of 78.57% at 0.05% v/v on mild steel specimen in 1?M H₂SO₄ medium at room temperature. Tafel polarizations clearly show that the aqueous extract of AHG acts as a mixed type inhibitor. The change in the EIS parameters in presence of inhibitor is investigative of the protective layer formation of the mild steel surface. The adsorption is found to obey Langmuir adsorption isotherm. Thermodynamic and activation parameters for the corrosion inhibition process supported the physical adsorption mechanism.     

Hector bases – a new class of heterocyclic corrosion inhibitors for mild steel in acid solutions

Three heterocyclic compounds namely 3-anilino-5-imino-4-phenyl-1, 2,4-thiadiazoline (AIPT), 3-anilino-5-imino-4-tolyl-1, 2,4-thiadiazoline (AITT), and 3-anilino-5-imino-4-chlorophenyl-1, 2,4-thiadiazoline (AICT) were synthesized and their influence on the inhibition of corrosion of mild steel in 1 M HCl and 0.5 M H₂SO₄ was investigated by weight loss and potentiodynamic polarization techniques. The values of activation energy and free energy of adsorption of these compounds were also calculated. Potentiodynamic polarization studies were carried out at room temperature, and showed that all the compounds were mixed type inhibitors causing blocking of active sites on the metal. The inhibition efficiency of the compounds was found to vary with concentration, temperature and immersion time. Good inhibition efficiency was evidenced in both acid solutions. The adsorption of the compounds on mild steel for both acids was found to obey the Langmuir adsorption isotherm. Electrochemical impedance spectroscopy was also used to investigate the mechanism of corrosion inhibition.     

Inhibition of mild steel corrosion in groundwater by pyrrole and thienylcarbonyl benzotriazoles

The inhibition efficiency of Zn²⁺, 3-phosphonopropionic acid (3-PPA), benzotriazole (BTA) and two synthesized benzotriazole derivatives namely 1-(2-pyrrole carbonyl) benzotriazole (PCBT) and 1-(2-thienylcarbonyl) benzotriazole (TCBT) were evaluated as inhibitors for the corrosion of mild steel in ground water. The inhibition efficiencies of PCBT and TCBT in combination with Zn²⁺ and 3-PPA were also investigated and the results were compared with BTA. In order to study the corrosion rate and inhibition efficiency we employed potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Further characterization using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) demonstrates the adsorption of inhibitor and the formation of corrosion products on the mild steel surface, respectively. Combination of PCBT along with Zn²⁺ and 3-PPA shows better corrosion inhibition efficiency than other inhibitor combinations and the individual inhibitors.     

Inhibition of mild steel corrosion in acidic medium using starch and surfactants additives

The corrosion inhibition of mild steel in 0.1M H₂SO₄ in presence of starch (polysaccharide) was studied using weight loss and potentiodynamic polarization measurements in the temperature range of 30–60°C. Starch inhibits the corrosion rates of mild steel to a considerable extent; the maximum inhibition efficiency (%IE) being 66.21% at 30^oC in presence of starch concentration of 200 ppm. The effect of the addition of very small concentration of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide on the corrosion inhibition behavior of starch was also studied. The IE of starch significantly improved in presence of both the surfactants. The effect of surfactants on the corrosion inhibition behavior of starch appears to be synergistic in nature. Starch alone and in combination with surfactants is found to obey Langmuir adsorption isotherm from the fit of the experimental data of all concentration and temperature studied. Phenomenon of physical adsorption is proposed from the trend of IE with temperature and also the values E_a, ΔG_ads, and Q_ads obtained. The results obtained by potentiodynamic polarization measurements are consistent with the results of the weight loss measurement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Experimental and Quantum Chemical Studies on Corrosion Inhibition Performance of Thiazolidinedione Derivatives for Mild Steel in Hydrochloric Acid Solution

In the present investigation, two thiazolidinedione derivatives, 5-[(2-(3,4,5-trimethoxyphenyl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazol-5-yl)methylidene]-1,3-thiazolidine-2,4-dione (Inh I) and 5-[2-(3,4,5-trimethoxyphenyl)-6-(4-methoxylphenyl)-imidazo[2,1-b][1,3,4]thiadiazol-5-yl)methylidene]-1,3-thiazolidine-2,4-dione (Inh II) were synthesized and investigated as inhibitors for mild steel corrosion in 15% HCl solution using the weight loss, electrochemical polarization, and electrochemical impedance spectroscopy (EIS) techniques. It was found that the inhibition efficiency of these inhibitors increased with increasing concentration. The effect of temperature on the corrosion rate was investigated, and some thermodynamic parameters were calculated. Polarization studies showed that both studied inhibitors were of mixed type in nature. The adsorption of inhibitors on the mild steel surface in acid solution was found to obey the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) was performed on inhibited and uninhibited mild steel samples to characterize the surface. The semi-empirical AM1 method was employed for theoretical calculation of highest (E _HOMO), and lowest unoccupied molecular orbital (E _LUMO) energy levels, energy gap (E _LUMO ? E _HOMO), dipole moment (μ), global hardness (γ), softness (σ), binding energy, molecular surface area, chemical potential (Pi), and the fraction of electrons transferred from the inhibitor molecule to the metal surface (ΔN). The results were found to be consistent with the experimental findings.     

Corrosion inhibition of aluminium in acid solutions by some imidazoline derivatives

2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI) were synthesized and characterized by FT-IR and NMR Studies. The corrosion inhibition properties of these compounds on aluminium in 1 M HCl and 0.5 M H₂SO₄ were investigated by weight loss, potentiodynamic polarization, electrochemical impedance and scanning electron microscopic techniques. The weight loss study showed that the inhibition efficiency increases with increase in the concentration of the inhibitor and was found to be inversely related to time and temperature while it shows no significant change with increase in acid concentration. The effectiveness of these inhibitors were in the order of UDI > NI > PDI > HDI .The values of activation energy, free energy of adsorption, heat of adsorption, enthalpy of activation and entropy of activation were also calculated to elaborate the mechanism of corrosion inhibition. The adsorption of these compounds on aluminium surface follows the Langmuir adsorption isotherm. The potentiodynamic polarization data show that the compounds studied are mixed type inhibitors. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The surface characteristics of inhibited and uninhibited metal samples were investigated by scanning electron microscopy (SEM).     

ANISALIDINE DERIVATIVES AS CORROSION INHIBITORS OF MILD STEEL IN ACIDIC MEDIA. 1

The corrosion inhibitory properties on mild steel in acidic media by nitrogen-containing ligands N-(4-nitro phenyl) p-anisalidine (SB1), N-(4-chloro phenyl) p-anisalidine (SB2), N-(4-phenyl) p-anisalidine (SB3), N-(4-methoxy phenyl) p-anisalidine (SB4), and N-(4-hydroxy phenyl) p-anisalidine (SB5) have been studied using mass loss, thermometric, and potentiostatic polarization techniques. Due to adsorption of the additive molecules on the metal surface the inhibition efficiency increases up to 98.85% with increasing additive concentration. A synergistic effect exists between the Schiff base additives and mild steel. The mechanistic effect of corrosion inhibition has been investigated by the potentiostatic polarization technique. The impact of temperature on the performance of these compounds clearly shows the effect of the decomposition and desorption of these compounds at higher temperatures.     

Synthesis of mono and bis-4-methylpiperidiniummethyl-urea as corrosion inhibitors for steel in acidic media

Mono and bis-4-methylpiperidiniummethyl urea were synthesized, characterized and used as new corrosion inhibitors of mild steel in the acidic media. Inhibitory effect of two compounds on mild steel surface in the 1 mol·L^-1 sulphuric acid has been studied by a series of techniques, such as potentiodynamic polarization, weight loss and quantum chemical calculation methods. Potentiodynamic polarization measurements showed that two inhibitors are mixed type. All measurements showed that inhibition efficiencies enhanced with increase of inhibitor concentration. This reveals that inhibitive actions of inhibitors were mainly due to adsorption on mild steel surface. Density functional (DFT) calculations have been carried out for the title compounds by performing HF and DFT levels of theory using the standard 6-31G* basis set.