Corrosion inhibition of mild steel in hydrochloric acid solution by Schiff base furoin thiosemicarbazone

A heterocyclic Schiff base furoin thiosemicarbazone was tested for its corrosion inhibition towards mild steel in 1 M HCl solution using weight loss, Tafel polarization and electrochemical impedance spectroscopy techniques. Furoin thiosemicarbazone revealed good corrosion inhibition efficiency even at low concentrations towards mild steel in HCl medium. Comparison of corrosion inhibition efficiency of Schiff base and its parent amine and effect of temperature on inhibition efficiency were also investigated. The adsorption of furoin thiosemicarbazone on mild steel surface obeys Langmuir isotherm.     

Corrosion control of mild steel using 3,5-bis(4-methoxyphenyl)-4-amino-1,2,4-triazole in normal hydrochloric acid medium

The inhibition performance of the 3,5-bis(4-methoxyphenyl)-4-amino-1,2,4-triazole (4-MAT) on mild steel in normal hydrochloric acid medium (1 M HCl) at 30 °C was tested by weight loss, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. This organic compound inhibits the acidic corrosion even at very low concentration, reaching a value of inhibition efficiency up to 98% at a concentration of 3 × 10⁻⁴ M. The results obtained from the different corrosion evaluation techniques are in good agreement. Polarisation curves indicate that 4-MAT is a mixed inhibitor, affecting both cathodic and anodic corrosion currents. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through appropriate equivalent circuit model, a constant phase element (CPE) has been used. The adsorption of 4-MAT on the steel surface, in 1 M HCl solution, obeys to Langmuir’s isotherm with a very high negative value of the free energy of adsorption ΔG°_ads (chemisorption). X-ray photoelectron spectroscopy (XPS) was carried out to establish the mechanism of corrosion inhibition of mild steel in 1 M HCl medium in the presence of 3,5-bis(4-methoxyphenyl)-4-amino-1,2,4-triazole (4-MAT).     

Corrosion inhibition efficiency and surface activity of benzothiazol-3-ium cationic Schiff base derivatives in hydrochloric acid

Two series of cationic Schiff base surfactants namely: 2-(benzylideneamino)-3-(2-oxo-2-alkoxyethyl)-1,3-benzothiazol-3-ium bromide and 2-[(4-methoxybenzylidene)amino]-3-(2-oxo-2-alkoxyethyl)-1,3-benzothiazol-3-ium bromide were prepared and confirmed using elemental analysis, FTIR, and ¹H NMR spectra. The surface activity of the synthesized Schiff bases showed their tendency towards adsorption at the interfaces. The prepared compounds were evaluated as corrosion inhibitors for carbon steel in 0.5 M HCl solution using gravimetric and polarization measurements. By fitting the gravimetric data, some thermodynamic and kinetic parameters were estimated. The adsorption of the inhibitors on the carbon steel surface obeyed Langmuir adsorption isotherm and had a physical mechanism. Polarization measurements showed that the synthesized inhibitors act as mixed inhibitors for carbon steel in the acidic media. The results of the corrosion inhibition using two different methods showed narrow differences in the obtained values between the two methods within 5%.     

Quinolin-5-ylmethylene-3-{[8-(trifluoromethyl)quinolin-4-yl]thio}propanohydrazide as an effective inhibitor of mild steel corrosion in HCl solution

Quinolin-5-ylmethylene-3-{[8-(trifluoromethyl)quinolin-4-yl]thio}propanohydrazide (QMQTPH) was synthesized, characterized and tested as a corrosion inhibitor for mild steel in 1 M and 2 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Polarization resistances calculated from the EIS measurements were in good agreement with those obtained from direct current (DC) polarization measurements. The mild steel samples were also analyzed by scanning electron microscopy (SEM). The results showed that QMQTPH is an excellent inhibitor for mild steel in acid medium. The inhibition was assumed to occur via adsorption of the inhibitor molecule on the metal surface. It acts as an anodic inhibitor. In the 30° to 60 °C temperature range, the QMQTPH adsorption follows Langmuir isotherm model. The protection efficiency increased with increasing inhibitor concentration in the range 10⁻⁵ − 10⁻³ M, but slightly decreased with increasing temperature.     

Application of some ferrocene derivatives in the field of corrosion inhibition

Three ferrocene derivatives, namely 1,1′-diacetylferrocene (Diacetyl Fc), 1,1′-diformylferrocene (Diformyl Fc) and 2-benzimidazolythioacetylferrocene (BIM Fc) were synthesized and their inhibitive effects against mild steel corrosion in aerated 0.5 M H₂SO₄ and 1 M HCl solutions were evaluated. Corrosion measurements based on polarization resistance (R_p), potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) indicate that Diacetyl Fc, in most cases, accelerates mild steel corrosion in HCl while Diformyl Fc and BIM Fc act as weak inhibitors. In H₂SO₄ solution, ferrocene derivatives show good inhibition performance. The efficiency of the inhibitors follows the order: BIM Fc > Diformyl Fc ? Diacetyl Fc. Adsorption of both Diacetyl Fc and Diformyl Fc obey Langmuir adsorption isotherm with very low value of free energy of adsorption ΔG^° for the Diformyl Fc (physisorption) while adsorption of BIM Fc follows that of Frumkin with high negative value of ΔG^° (chemisorption). Both Diformyl Fc and BIM Fc act as mixed-type inhibitors with predominant effect on the anodic dissolution of iron. Analysis of the polarization curves and impedance spectra indicates that charge transfer process mainly controls mild steel corrosion in H₂SO₄ solution without and with ferrocene compounds. The mechanism of corrosion inhibition or acceleration by ferrocene derivatives was discussed in the light of the molecular structure of the additives.     

Inhibition effect of nonionic surfactant on the corrosion of cold rolled steel in hydrochloric acid

The inhibition effect of Tween-20 as a nonionic surfactant on the corrosion of cold rolled steel (CRS) in 1.0-8.0 M HCl has been studied at different temperatures (20-50 °C) by weight loss and potentiodynamic polarization methods. Atomic force microscope (AFM) provided the CRS surface conditions. The results show that Tween-20 is a good inhibitor in 1.0 M HCl, and the inhibition efficiency (IE) increases with the inhibitor concentration, while decreases with increasing the hydrochloric acid concentration and temperature. Effect of immersion time was also studied and discussed. The adsorption of inhibitor on the CRS surface obeys the Langmuir adsorption isotherm equation. Both thermodynamic and kinetic parameters have been obtained by adsorption theory and kinetic equations. The inhibition effect is satisfactorily explained by the parameters. Polarization curves show that Tween-20 is a mixed-type inhibitor in hydrochloric acid. The results obtained from weight loss and polarization are in good agreement, and Tween-20 inhibition action could also be evidenced by surface AFM images.     

Adsorption and inhibitive properties of some new Mannich bases of Isatin derivatives on corrosion of mild steel in acidic media

Adsorption of four derivatives of piperidinylmethylindoline-2-one on mild steel surface in 1 M HCl solution and its corrosion inhibition properties has been studied by a series of techniques, such as polarization, electrochemical impedance spectroscopy (EIS), weight loss and quantum chemical calculation methods. The values of activation energy (E_a) for mild steel corrosion and various thermodynamic parameters were calculated and discussed. Potentiodynamic polarization measurements showed that all inhibitors are mixed type. The degree of surface coverage was determined by using weight loss measurements and it was found that adsorption process of studied inhibitors on mild steel surface obeys Langmuir adsorption isotherm.     

Corrosion inhibition of mild steel in hydrochloric acid solution by some double Schiff bases

The inhibition effect of four double Schiff bases on the corrosion of mild steel in 2 M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. The inhibitors were adsorbed on the steel surface according to the Langmuir adsorption isotherm model. From the adsorption isotherm, some thermodynamic data for the adsorption process were calculated and discussed. Kinetic parameters activation such as E_a, ΔH∗, ΔS∗ were evaluated from the effect of temperature on corrosion and inhibition processes. Quantum chemical calculations have been performed and several quantum chemical indices were calculated and correlated with the corresponding inhibition efficiencies.     

Experimental and molecular dynamics studies on corrosion inhibition of mild steel by 2-amino-5-phenyl-1,3,4-thiadiazole

The corrosion inhibition of mild steel in 0.5 M H₂SO₄ and 1.0 M HCl by 2-amino-5-phenyl-1,3,4-thiadiazole (APT) has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results show that the inhibition efficiency increases with the increase of APT concentration in both acids, and the higher inhibition efficiency is obtained in 0.5 M H₂SO₄. The adsorption of APT molecules on the steel surface obeys Langmuir adsorption isotherm in both acids, and occurs spontaneously. The molecular dynamics method has also been used to simulate the adsorption of ATP molecule and solvent ions on the iron surface. The results show that with the adsorption of sulfate ions the Fe + anion + APT system has the higher negative interaction energy comparing to the case of the adsorption of chloride ions.     

Thermodynamic, electrochemical and quantum chemical investigation of some Schiff bases as corrosion inhibitors for mild steel in hydrochloric acid solutions

The corrosion inhibition of mild steel in 1.0 M HCl solution by four Schiff bases was investigated using weight loss and electrochemical measurements and quantum chemical calculations. All compounds showed >90% inhibition efficiency at their optimum concentrations. The activation energy (E_a) of corrosion and other thermodynamic parameters were calculated to elaborate the mechanism of corrosion inhibition. The adsorption of the inhibitors on the mild steel surface follows Langmuir isotherm model. Polarization studies indicated that all studied inhibitors are mixed type. The computed quantum chemical properties viz., electron affinity (EA) and molecular band gap (ΔE_MBG) show good correlation with experimental inhibition efficiencies.     

A cationic gemini-surfactant as effective inhibitor for mild steel in HCl solutions

A cationic gemini-surfactant, namely 1,4-bis (1-chlorobenzyl-benzimidazolyl)-butane (CBB) was synthesized and its inhibition effect on the corrosion of mild steel in 0.5 M HCl solution was investigated by weight loss and electrochemical techniques. The results showed that CBB acts as an excellent corrosion inhibitor in 0.5 M HCl by suppressing simultaneously the cathodic and anodic processes via chemical adsorption on the surface of steel, which followed the Langmuir adsorption isotherm. The inhibition efficiency increased with the increase of CBB concentration and temperature. The adsorption mechanism of the compound was discussed in terms of thermodynamic and kinetic parameters deduced from the experimental data.     

Electrochemical effect of cationic gemini surfactant and halide salts on corrosion inhibition of low carbon steel in acid medium

In this paper, the corrosion inhibition of cationic gemini surfactant, in the absence and presence of halide salts (NaCl, NaBr and NaI) on steel in HCl was investigated at 20 ± 1 °C. The effects of pH, immersion time and salt concentration on the corrosion inhibition of steel were studied using weight loss, open circuit potential and electrochemical impedance spectroscopy. Inhibition efficiency increases by increasing surfactant concentration. Synergistic effect between surfactant and salts was studied. The inhibition efficiency increases by increasing salt concentration. This composite inhibitor containing gemini surfactant and halide was efficient and low-cost for steel corrosion inhibition in HCl.     

The effect of some bis-thiadiazole derivatives on the corrosion of mild steel in hydrochloric acid

The inhibition effect of bis-thiadiazole derivatives (BTDs) against the corrosion of mild steel in 1 M HCl solution was studied by weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. All the BTDs exhibited >90% inhibition efficiency at concentration as low as 40 ppm. The adsorption of BTDs obeyed Langmuir adsorption isotherm. Both thermodynamic and activation parameters were calculated and discussed. Polarization curves indicate that they are mixed type of inhibitors. All the BTDs were adsorbed physically at lower concentration where as chemisorption was favoured at higher concentration.     

Cefotaxime sodium: A new and efficient corrosion inhibitor for mild steel in hydrochloric acid solution

The corrosion inhibition of mild steel in 1 M HCl solution by cefotaxime sodium has been studied by Tafel polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The inhibitor showed 95.8% inhibition efficiency at optimum concentration 300 ppm. Results obtained revealed that inhibition occurs through adsorption of the cefotaxime on metal surface without modifying the mechanism of corrosion process. Potentiodynamic polarization studies suggest that it is a mixed type of inhibitor. Electrochemical impedance spectroscopy techniques were also used to investigate the mechanism of corrosion inhibition.     

Tryptamine as a corrosion inhibitor of mild steel in hydrochloric acid solution

The inhibitor effect of tryptamine on the corrosion of mild steel in 0.5 M hydrochloric acid at 30 °C was investigated using linear polarization, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency increases with an increase in concentration of tryptamine. At 500 ppm tryptamine the inhibition efficiency calculated by these techniques is around 97%. Cathodic and anodic polarization curves of mild steel in the presence of different concentrations of tryptamine at 30 °C reveal that it is a mixed type inhibitor. Tryptamine follows Langmuir adsorption with adsorption free energy of −35.07 kJ mol⁻¹.     

Investigation on some Schiff bases as corrosion inhibitors for mild steel

In the present work, the effect of some newly synthesized Schiff bases containing sulphur nitrogen as heteroatom was investigated on mild steel corrosion in acidic media. Electrochemical studies of the mild steel samples were performed in an aerated solution of 0.1 M HCl + dimethyl sulphoxide (DMS) as co-solvent. DMS is also behaving as a corrosion inhibitor for mild steel. At low inhibitor concentration and short immersion time one can see only the inhibitive effect of DMS as anodic inhibitor for mild steel. At high concentration and long immersion time inhibition efficiencies are increased and cathodic inhibition is observed.     

The inhibitive effect of some bis-N,S-bidentate Schiff bases on corrosion behaviour of 304 stainless steel in hydrochloric acid solution

The inhibition effect of four new Schiff bases on the corrosion of 304 stainless steel in 1 M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. Polarization curves indicated that all studied Schiff bases act as mixed type (cathodic/anodic) inhibitors. The adsorption of the inhibitors was well described by the Langmuir adsorption isotherm and the adsorption isotherm parameters (K_ads, ΔG_ads) were determined at room temperature. Effect of temperature on the efficiency of the corrosion inhibition process was studied and the values of activation energy, pre-exponential factor (λ), enthalpy of activation and entropy of activation were calculated to elaborate the mechanism of corrosion inhibition. Differences in inhibition efficiency between four tested inhibitors are correlated with their chemical structures.     

Synergistic effect of halide ions on improving corrosion inhibition behaviour of benzisothiozole-3-piperizine hydrochloride on mild steel in 0.5 M H2SO4 medium

The synergistic effect of iodide ions and benzisothiozole-3-piperizine hydrochloride (BITP) on corrosion inhibition of mild steel in 0.5 M H₂SO₄ solution has been studied by both chemical and electrochemical methods. The corrosion performance of BITP in 1.0 M HCl and 0.5 M H₂SO₄ media was examined and compared. The adsorption of BITP and its combination with iodide ions on mild steel surface followed Langmuir adsorption isotherm via chemisorption mechanism. The calculated values of synergism parameter (S_θ) were found to be greater than unity. This result clearly showed the existence of synergism between iodide ions and BITP molecules.     

Adsorption properties and inhibition of mild steel corrosion in hydrochloric solution by some newly synthesized diamine derivatives: Experimental and theoretical investigations

New diamine derivatives, namely 2-[{2-[bis-(2-hydroxyethyl)amino]ethyl}(2-hydroxyethyl)amino]ethanol (DAME) and 2-[{2-[bis-(2-hydroxyethyl)amino]ethyl}(2-hydroxyethyl)amino]propanol (DAMP) were synthesised and their inhibitive action against the corrosion of mild steel in 1 M HCl solution were investigated at 308 K. The detailed study of DAME is given using gravimetric measurements and polarization curves method. Results show that DAME is a good inhibitor and inhibition efficiency reaches 91.7% at 10⁻³ M. Tafel polarization study revealed that DAME acts as a mixed-type inhibitor. The inhibitor adsorption process in mild steel/DAME/hydrochloric acid system was studied at different temperatures (308-353 K) by means of weight loss measurements. The adsorption of DAME on steel surface obeyed Langmuir’s adsorption isotherm. The kinetic and thermodynamic parameters for mild steel corrosion and inhibitor adsorption, respectively, were determined and discussed. The comparative study of inhibitive performance of the two diamine derivatives revealed that DAME is more effective than DAMP. Quantitative Structure-Activity Relationship (QSAR) approach has been conducted in attempt to correlate the corrosion inhibition properties of these diamine derivatives with their calculated quantum chemical parameters.     

The effect of ionic liquids with imidazolium and pyridinium cations on the corrosion inhibition of mild steel in acidic environment

Ionic liquids with chemical formula 1,3-dioctadecylimidazolium bromide and N-Octadecylpyridinium bromide were synthesized by conventional and microwave-assisted reactions, respectively. Ionic liquids tested as corrosion inhibitors after polarization curves displayed corrosion protection efficiency within 82-88% at 100 ppm for mild steel in a 1 M aqueous solution of sulfuric acid. Standard free energy indicated that corrosion inhibition occurred by a chemical adsorption process. Surface analysis (SEM, EDX) completed by XRD and Mössbauer spectroscopy indicated the presence of carbon species pertaining to inhibitor and corrosion products, which was rationalized in an inhibition mechanism.