Acridine-based thiosemicarbazones as novel inhibitors of mild steel corrosion in 1 M HCl: synthesis,electrochemical, DFT and Monte Carlo simulation studies

Electrochemical, surface morphology, density functional theory and Monte Carlo simulation methods were employed in investigating the effects of (2E,2′E)-2,2′-(3,3,6,6-tetramethyl-9-phenyl-3,4,6,7-tetrahydroacridine-1,8(2H,5H,9H,10H)-diylidene)bis(N-phenylhydrazinecarbothioamide) (IAB-NP), (2E,2′E)-2,2′-(3,3,6,6-tetramethyl-9-phenyl-3,4,6,7-tetrahydroacridine-1,8(2H,5H,9H,10H)-diylidene)bis(N-(2,4-difluorophenyl)hydrazinecarbothioamide)IAB-ND) and (2E,2′E)-2,2′-(3,3,6,6-tetramethyl-9-phenyl-3,4,6,7-tetrahydroacridine-1,8(2H,5H,9H,10H)-diylidene)bis(N-(2-fluorophenyl) hydrazinecarbothioamide) (IAB-NF) on mild steel corrosion in 1 M HCl solution. From the studies, compounds IAB-NP, IAB-ND and IAB-NF inhibit mild steel corrosion in the acid and the protection efficiencies were found to increase with the increase in concentration of each compound. At the optimum inhibitor concentration of 1.5 × 10⁻⁴ M, the inhibition efficiencies (%) of the compounds are in the order IAB-NF (90.48) > IAB-ND (87.48) > IAB-NP (85.28). Potentiodynamic polarization measurements revealed that all the compounds acted as mixed-type corrosion inhibitors. Experimental data for the adsorption of the studied molecules on a mild steel surface in 1 M HCl fitted into the Langmuir adsorption isotherm and the standard free energies of adsorption (ΔG^o_ads) suggested both physisorption and chemisorption mechanisms. Scanning electron microscopy analyses confirmed the formation of a protective film on the mild steel surface by the inhibitor molecules, resulting in protection of the metal from corrosive electrolyte ions. The experimental findings were corroborated by both theoretical density functional theory and Monte Carlo simulation studies.

Three novel acridine-based thiosemicarbazones were investigated for their corrosion inhibition potentials on mild steel in 1 M HCl using combined electrochemical, DFT and Monte Carlo simulation techniques.     

Synthesis,characterization and electrochemical analysis of cysteine modified polymers for corrosion inhibition of mild steel in aqueous 1 M HCl

Butler''s cyclopolymerization protocol was used to synthesize homo and copolymers of cysteine residues and diallyldimethylammonium chloride (DADMAC) using water as a solvent and excellent yields were obtained. The structural composition of the polymers was determined using nuclear magnetic resonance (NMR) and Fourier-transform infrared (FT-IR) spectroscopies. The thermal stability of the synthesized polymers was determined using thermogravimetric analysis (TGA). The corrosion efficiencies and adsorption characteristics of these polymers on mild steel were evaluated using gravimetric weight loss and potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The copolymers of cysteine residues and DADMAC exhibited excellent inhibition efficiencies in arresting mild steel corrosion in 1 M hydrochloric acid (HCl) at 60 °C. The best fitted Langmuir, Temkin and Freundlich adsorption isotherms suggested that the adsorption process occurs through chemisorption and physisorption. The surface morphology of mild steel in the presence or absence of polymers was determined using atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). This systematic study might provide a way to design new inhibitor compounds that could be beneficial in the field of biomedical science as well as for anti-corrosion applications.

Mild steel framework embedded in corrosion inhibiting structural motifs.     

Adsorption and anti-corrosion characteristics of vanillin Schiff bases on mild steel in 1 M HCl: experimental and theoretical study

Herein, two Schiff base derivatives of vanillin and divanillin with 2-picolylamine, namely, 2-methoxy-4-((pyridin-2-ylmethylimino)methyl)phenol (compound A) and 3,3′-dimethoxy-5,5′-bis-((pyridin-2-ylmethylimino)methyl)-[1,1′-biphenyl]-2,2′-diol (compound B), respectively, were synthesized. Additionally, their adsorption characteristics and corrosion inhibition behavior were compared for mild steel in 1 M HCl using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss methods. Compound B was found to impart a better anti-corrosive effect (around 95% inhibition efficiency at 313 K) than compound A. The inhibitors act as effective mixed-type inhibitors and exhibit Langmuir-type adsorption behaviour. The kinetic–thermodynamic parameters together with the data obtained from density functional theory (DFT) and molecular dynamics (MD) simulations illustrate the mechanism of corrosion and mode of adsorption of both inhibitors on the metal surface. The better corrosion mitigation propensity of the dimeric form of the inhibitor (compound B) over the monomeric form (compound A) was tested experimentally and explained according to the theoretical data.

Two Schiff base derivatives of vanillin and divanillin with 2-picolylamine are synthesized and their anti-corrosive propensity for mild steel in aqueous HCl are compared.     

Functional polyaspartic acid derivatives as eco-friendly corrosion inhibitors for mild steel in 0.5 M H2SO4 solution

To improve the corrosion inhibition efficiency of eco-friendly polyaspartic acid (PASP) for mild steel in acidic solutions, PASP/N-(3-aminopropyl)imidazole (PD-1) and PASP/N-(3-aminopropyl)-imidazole-co-n-dodecylamine (PD-2) were chemically synthesized by the facile ring-opening reaction of polysuccinimide. Inhibition efficiencies of PD-1 and PD-2 for mild steel in a 0.5 M H₂SO₄ solution were investigated by electrochemical measurements (electrochemical impedance and polarization) and the weight loss method. In comparison with PASP, PD-1 and PD-2 show improved inhibition efficiencies due to the functional groups. In particular, PD-2 shows superior corrosion inhibition capacity, and the efficiency is up to 94% at a relatively low concentration of 100 mg L⁻¹ at 298 K, as determined by potentiodynamic polarization measurements. Surface analysis of mild steel with PD-2 as an inhibitor clearly indicates that the inhibitor molecules adsorb on the steel surface and efficiently inhibit the corrosion of mild steel. The present work provides very meaningful results in designing and preparing new polymer inhibitors with high inhibition efficiency.

To improve the corrosion inhibition efficiency of polyaspartic acid (PASP) for mild steel in acidic solutions, PASP/N-(3-aminopropyl)imidazole (PD-1) and PASP/N-(3-aminopropyl)-imidazole-co-n-dodecylamine (PD-2) were synthesized.     

Rheological,electrochemical, surface,DFT and molecular dynamics simulation studies on the anticorrosive properties of new epoxy monomer compound for steel in 1 M HCl solution

A new epoxy monomer, namely, tetraglycidyl-1,2-aminobenzamide (ER), was synthesized by condensation of the amines with epichlorohydrin in a basic medium. The obtained epoxy monomer was characterized by FT-IR and ¹H NMR spectroscopy. Rheological properties of this monomer were determined using an advanced rheometer. Subsequently, the synthesized ER monomer was investigated as corrosion inhibitor for carbon steel in 1 M HCl solution. The adsorption properties of ER were analyzed by electrochemical, surface investigation and theoretical computational studies using DFT and molecular dynamics (MD). Results showed a high dependence of the viscosity of ER on temperature and concentration, and also, that ER has better inhibition performance. A good agreement between the results derived from computational (MD and DFT) and experimental methods was observed. The thermodynamic parameters, along with the kinetic parameters, showed that the adsorption of ER molecules onto carbon steel surface obeyed the Langmuir isotherm model, and the adsorption at metal–electrolyte interfaces involved both chemical and physical adsorption, but predominantly chemisorption mechanism.

A new epoxy monomer, namely, tetraglycidyl-1,2-aminobenzamide (ER), was synthesized by condensation of the amines with epichlorohydrin in a basic medium.     

The inhibition of mild steel corrosion in 0.5 M H2SO4 solution by radish leaf extract

The inhibitory effect of radish leaf extract (RLE) on mild steel corrosion in 0.5 M H₂SO₄ was studied by the weight loss method and the electrochemical method. The results demonstrated that the efficiency of inhibition increased with an increase in the concentration of RLE and decreased with an increase in temperature. The inhibition performance reached 93% with 300 mg L⁻¹ at 298 K. RLE behaved as a mixed-type inhibitor based on the cathode. The inhibition mechanism involved the adsorption of the active ingredients of RLE on the mild steel surface to prevent corrosion. The adsorption followed the Langmuir adsorption isotherm, and physical and chemical adsorption coexisted. The results were supported by SEM, quantum chemical calculations, FTIR and UV-visible spectroscopy analyses.

The inhibitory effect of radish leaf extract (RLE) on mild steel corrosion in 0.5 M H₂SO₄ was studied by the weight loss method and the electrochemical method.     

Isoxazolidine derivatives as corrosion inhibitors for low carbon steel in HCl solution: experimental,theoretical and effect of KI studies

Two isoxazolidine derivatives namely 5-(benzo[d][1,3]dioxol-5-ylmethyl)-2-tetradecyl isoxazolidine (BDMTI) and 5-(4-hydroxy-3-methoxybenzyl)-2-tetradecyl isoxazolidine (HMBTI) were synthesized and characterized using FTIR, C-NMR, H-NMR, and elemental analysis. The synthesized compounds were evaluated as corrosion inhibitors for API 5L X60 steel in 1 M HCl in the temperature range of 25–60 °C using gravimetric and electrochemical (Electrochemical Impedance Spectroscopy (EIS), Potentiodynamic Polarization (PDP) and Linear Polarization Resistance (LPR)) techniques. The effect of addition of a small amount of iodide ions on the corrosion inhibition performance of the compounds was also assessed. In addition, quantum chemical calculations and Monte Carlo simulations were employed to correlate the electronic properties of the compounds with the corrosion inhibition effect as well as to evaluate the adsorption/binding of the inhibitor molecules on the steel surface. Experimental results show that the two compounds inhibited the corrosion of carbon steel in an acid environment with HMBTI showing superior performance. The corrosion inhibition effect was found to be dependent on the inhibitors'' concentration and temperature. Addition of iodide ions improves the inhibition efficiency considerably due to co-adsorption of the iodide ions and the inhibitors on the steel surface which was competitive in nature as confirmed from the synergistic parameter (S₁) which was less than unity at higher temperature. Experimental and theoretical results are in good agreement.

Two isoxazolidine derivatives (BDMTI and HMBTI) were synthesized and characterized using FTIR, C-NMR, H-NMR and elemental analysis and evaluated as corrosion inhibitors for X60 steel in 1 M HCl solution.     

Natural parsley oil as a green and safe inhibitor for corrosion of X80 carbon steel in 0.5 M H2SO4 solution: a chemical,electrochemical, DFT and MC simulation approach

This work focuses on the use of natural parsley oil as a safe, eco-friendly and cost-effective inhibitor for dissolution of X80 carbon steel (X80CS) in 0.5 M H₂SO₄ solution. Electrochemical and chemical measurements and theoretical studies were utilized to determine the inhibitory vigor of parsley oil. The inhibition efficacy increases with an increase in the parsley oil concentration and a decrease in temperature. It reached 95.68% at 450 ppm of parsley oil. The inhibition process is explained by spontaneous adsorption of the oil on the X80CS. Adsorption is described by the Langmuir isotherm model. The polarization data demonstrate that parsley oil is categorized as a mixed inhibitor with a dominant control of the cathodic reaction. Parsley oil inhibits the pitting corrosion of X80CS in the presence of NaCl solution by moving the pitting potential to a more positive mode indicating protection against pitting attack. The thermodynamic parameters for activation and adsorption were computed and interpreted. The four chemical components in natural parsley oil were examined using density functional theory (DFT). Monte Carlo (MC) simulation was performed to study the adsorption of parsley oil on the X80CS surface. The outcomes confirmed that the Apiole molecule is the most effective in the inhibition process.

This work focuses on the use of natural parsley oil as a safe, eco-friendly and cost-effective inhibitor for dissolution of X80 carbon steel (X80CS) in 0.5 M H₂SO₄ solution.     

A combination of experiment and theoretical methods to study the novel and low-cost corrosion inhibitor 1-hydroxy-7-azabenzotriazole for mild steel in 1 M sulfuric acid

1-Hydroxy-7-azabenzotriazole (HOAT) was explored via experimental and theoretical computation methods as a corrosion inhibitor for mild steel in 1 M sulfuric acid. These data indicate that HOAT has good ability to suppress corrosion of the mild steel, with ideal agreement with between experimental and computational results. Besides, the electrochemical experiments show that HOAT is a mixed-type corrosion inhibitor for mild steel in 1 M H₂SO₄. Furthermore, HOAT adsorption on the surface of steel conforms to the Langmuir isotherm model. Finally, computational simulation was executed to deeply investigate the mechanism to HOAT inhibition corrosion of steel.

1-Hydroxy-7-azabenzotriazole (HOAT) was explored via experimental and theoretical computation methods as a corrosion inhibitor for mild steel in 1 M sulfuric acid.