Correlated experimental and theoretical study on inhibition behavior of novel quinoline derivatives for the corrosion of mild steel in hydrochloric acid solution

Cysteine as an Eco-Friendly Anticorrosion Inhibitor for Mild Steel in Various Acidic Solutions: Electrochemical, Adsorption, Surface Analysis, and Quantum Chemical Calculations

The corrosion of iron in acidic environments has a negative impact on global industry. Herewith, the inhibitory effect of cysteine (Cys.) on mild steel (MSL) corrosion in different acidic solutions (1 M HCl, 1 M H2SO4, and 1 M H3PO4) was investigated through weight loss, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy, scanning electron microscopy (SEM), and theoretical calculations. The measurement results indicated that the adsorption of Cys. molecules on the metal surface caused corrosion inhibition. As a result, a protective layer or insoluble compound, or both, is obtained, blocking the active sites, preventing corrosion. The effectiveness (IE %) of the Cys. was enhanced by increasing concentration and lowering temperature. The maximum IE % of inhibition at 1 × 10-2 M of Cys. obtained are 97.3, 89.7, and 84.4% in HCl, H3PO4, and H2SO4 solutions, respectively. At the same inhibitor concentration, the double-layer capacity decreased, and the charge-transfer resistance increased from 17.17 to 188.5, 3.564 to 31.91, and 1.325 to 8.715 Ω cm2 in HCl, H3PO4, and H2SO4 solutions, respectively. Adsorption and PDP studies confirmed that it obeys the Langmuir adsorption isotherm and acts as a mixed-type inhibitor of physicochemical nature. The corresponding thermodynamic and kinetic parameters were also calculated and discussed. Moreover, the inhibitory effect on the surface was inspected by SEM. The findings demonstrated that the order of IE % using Cys as anticorrosion agent for MSL is HCl > H3PO4 > H2SO4 solutions.

New benzisoxazole derivative: A potential corrosion inhibitor for mild steel in 0.5 M hydrochloric acid medium -insights from electrochemical and density functional theory studies

6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole. HCl (FPBH), a substituted benzisoxazole derivative, was prepared from isonipecotic acid and characterized using various spectroscopic techniques. Using electrochemical examinations such as potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopic (EIS) technique, the corrosion mitigation capabilities of this compound for mild steel (MS) in 0.5 M HCl medium were investigated. Theoretical studies were performed using quantum chemical calculations and density functional theory (DFT). PDP results exhibited the mixed-type behavior of FPBH and showed a maximum efficiency of 94.5 % at 1 × 10-3 M. The development of a protective adsorbed layer of FPBH decreases the corrosion current density (icorr) and corrosion rate (CR). The EIS technique revealed that the rise in the charge transfer resistance (Rct) values and reduction in the thickness of the double-layer capacitance (Cdl) reflected the drop in corrosion rate. The adsorption of FPBH took place through physisorption by conforming Langmuir's isotherm. The DFT method was performed on the optimized structure of FPBH to get additional evidence on the action mode of FPBH with the metal surface.

1-Butyl-3-methylimidazolium methane sulfonate ionic liquid corrosion inhibitor for mild steel alloy: Experimental, optimization and theoretical studies

The current research reports the performance of 1-butyl-3-methylimidazolium methane sulfonate ([C4MIM][OMs](IL)) as effective corrosion inhibitor for mild steel in 1 M H2SO4 electrolyte. For proper evaluation, weight loss, electrochemical study, theoretical modeling and optimization techniques were used. Weight loss and electrochemical methods shows that the inhibition performance of [C4MIM][OMs] on the metal surface strengthens as the concentration increases. Maximum inhibition efficiency of 85.71%, 92.5% and 91.1% at 0.8 g L-1 concentration of [C4MIM][OMs] were obtained from the weight loss, polarization and impedance studies, respectively. In addition, response surface methodology (RSM) a statistical tool was used for modeling and optimization of the empirical data. The RSM model validates the empirical findings. Also, DFT/MD-simulation investigations evidenced that [C4MIM][OMs] forms a barrier film on the mild steel surface. The result shows that the synthesized [C4MIM][OMs] could open up opportunities in corrosion and materials protection for sustainability.

The inhibitive action of 2-mercaptobenzothiazole on the porosity of corrosion film formed on aluminum and aluminum-titanium alloys in hydrochloric acid solution

2-Mercaptobenzothiazole (2-MBT) in a solution of 0.5 M HCl is an effective corrosion inhibitor for aluminum and aluminum-titanium alloys. Tafel polarization and electrochemical impedance spectroscopy (EIS) were employed to assess this heterocyclic compound's anticorrosive potential and complementary by scanning electron microscope (SEM) and calculating porosity percentage in the absence and presence of various inhibitor concentrations. Inhibition efficiency (IE%) was strongly related to concentration (10^-6-10^-3 M). Temperature's effect on corrosion behavior was investigated. The data exhibited that the IE% decreases as the temperature increases. An increase in activation energy (E_a) with increasing the inhibitor concentration and the decrease in the IE% value of the mentioned compound with raising the temperature indicates that the inhibitor molecules are adsorbed physically on the surface. Thermodynamic activation parameters for Al and Al-Ti alloy dissolution in both 0.5 M HCl and the inhibited solution were calculated and discussed. According to Langmuir's adsorption isotherm, the inhibitor molecules were adsorbed. The evaluated standard values of the enthalpy ([Formula: see text], entropy ([Formula: see text] and free energy changes ([Formula: see text] showed that [Formula: see text] and [Formula: see text] are negative, while [Formula: see text] was positive. The formation of a protective layer adsorbed on the surfaces of the substrates was confirmed with the surface analysis (SEM). The porosity percentage is significantly reduced in the inhibitor presence and gradually decreased with increasing concentration. Furthermore, the density functional theory (DFT) and Monte Carlo (MC) simulations were employed to explain the variance in protecting the Al surface from corrosion. Interestingly, the theoretical findings align with their experimental counterparts. The planarity of 2-MBT and the presence of heteroatoms are the playmakers in the adsorption process.

Antipsychotic drug waste: A potential corrosion inhibitor for mild steel in the oil and gas industry

In this study, the corrosion inhibition efficiency of thioridazine hydrochloride (TH), an antipsychotic drug, on mild steel (commonly used pipeline material in the oil and gas industry) in 1 M hydrochloric acid (HCl) was evaluated using electrochemical techniques and weight loss method. Electrochemical impedance spectroscopy (EIS) results suggest that TH significantly enhances the polarization resistance (R_p) of mild steel. Similarly, potentiodynamic polarization results showed that the corrosion current density (i_corr) of mild steel decreased significantly with addition of TH. To understand the long-term effect of TH, mild steel was tested for 7 days in 100 ppm TH containing electrolyte. EIS results showed that the R_p did not change significantly after 24 h exposure as compared to 2 h exposure; whereas the R_p increased by 28% after 7-day exposure. Weight loss measurements revealed that the inhibition efficiency of TH is remarkably high (98.8%) after 7-day exposure. The adsorption free energy calculation suggests that at the initial stage (1-day) of mild steel exposure, TH was physically adsorbed onto the surface. However, at a later stage (7- day) the binding of TH was chemical, and hence the corrosion protection increased with increase in the exposure period. As compared to the wide range of corrosion inhibitors reported in the literature, TH has shown to be highly effective for mild steel. Thus, it can be suggested that TH drug waste is a potential corrosion inhibitor for mild steel pipelines in the oil and gas industry.

Experimental and computational chemical studies on the corrosion inhibitive properties of carbonitrile compounds for carbon steel in aqueous solutions

The present work aims to study 6-amino-4-aryl-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile derivatives namely: 6-Amino-2-oxo-1,4-diphenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-H), 6-Amino-2-oxo-1-phenyl-4-(p-tolyl)-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-Me) and 6-Amino-4-(4-hydroxyphenyl)-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-OH) as corrosion inhibitors to provide protection for carbon steel in a molar hydrochloric acid medium. Chemical measurements such as (weight loss) and electrochemical techniques such as (Potentiodynamic polarization, electrochemical impedance spectroscopy, and Electron frequency modulation) were applied to characterize the inhibitory properties of the synthesized derivatives. The adsorption of these derivatives on the carbon steel surface was confirmed by Attenuated Total Refraction Infrared (ATR-IR), Atomic Force Microscope (AFM), and X-ray Photoelectron Spectroscopy (XPS). Our findings revealed that the tested derivatives have corrosion inhibition power, which increased significantly from 75.7 to 91.67% on the addition of KI (PdC-OH:KI = 1:1) to inhibited test solution with PdC-OH derivative at 25 °C. The adsorption process on the metal surface follows the Langmuir adsorption model. XPS analysis showed that the inhibitor layer consists of an iron oxide/hydroxide mixture in which the inhibitor molecules are incorporated. Computational chemical theories such as DFT calculations and Mont Carlo simulation have been performed to correlate the molecular properties of the investigated inhibitors with experimental efficiency. The theoretical speculation by Dmol3 corroborates with the results from the experimental findings.

Inhibition of Mild Steel Corrosion by 4-benzyl-1-(4-oxo-4-phenylbutanoyl)thiosemicarbazide: Gravimetrical, Adsorption and Theoretical Studies

Gravimetric measurements were applied to study the inhibitory effect of 4-benzyl-1-(4-oxo-4-phenylbutanoyl)thiosemicarbazide (BOT) on the corrosion of mild steel in 1.0 M HCl. BOT has a good inhibitory efficacy of 92.5 percent at 500 ppm, according to weight loss results. The effect of inhibitor concentration on the mild corrosion behavior of steel was investigated and it was discovered that the higher the inhibitor concentration, the higher the damping efficiency. The results confirm that BOT is an effective corrosion inhibitor for mild steel in the presence of 1.0 M HCl. Furthermore, the higher protection efficiency with increasing temperature and the free energy value showed that BOT molecules participate in both chemisorption (coordination bonds between the active sites of BOT molecules and d-orbital of iron atoms) and physisorption (through the physical interactions on the mild steel surface). The adsorption mechanism on the mild steel surface obeys the Langmuir adsorption isotherm model. Quantum chemical calculations based on the DFT calculations were conducted on BOT. DFT calculations indicated that the protective efficacy of the tested inhibitor increased with the increase in energy of HOMO. The theoretical findings revealed that the broadly stretched linked functional groups (carbonyl and thionyl) and heteroatoms (sulfur, nitrogen and oxygen) in the structure of tested inhibitor molecules are responsible for the significant inhibitive performance, due to possible bonding with Fe atoms on the mild steel surface by donating electrons to the d-orbitals of Fe atoms. Both experimental and theoretical findings in the current investigation are in excellent harmony.

Expired Chicken Egg-White Extract’s Adsorption Behavior As a Corrosion Inhibitor for Carbon Steel in 1M HCl

The inhibitory activity of the expired egg-white carbon steel (CS) extract in HCl solution was studied in this article. The extract was examined using FT-IR, and the surface was examined using a scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDX). Weight loss techniques at various temperatures were used to examine corrosion investigations (298, 308, 318, and 328 K), concentrations (100, 200, 400, and 800 mg. L−1) of extracts, and electrochemical measurements (potentiodynamic polarization (PDP) and impedance spectroscopy (EIS) at 25°C and different concentrations. Results. Results obtained through EIS demonstrated a maximal inhibition efficiency of 90% at an inhibitor concentration of 800 mg. L−1. Moreover, the findings of the potentiodynamic polarization indicated that egg-white extract was a mixed type of inhibitor and slowed down both cathodic and anodic reactions. For weight loss analysis, an inhibitory potency (89, 83, 77, and 71%) at various temperatures (298, 308, 318, and 328 K) was demonstrated, respectively. It indicates that the temperature rise contributes to a decrease in the resistance of the carbon steel. The adsorption of the expired egg-white extract was spontaneous with physisorption and chemisorption according to the Langmuir isotherm model, according to adsorption isotherm studies.

Improving the sustainability of biodiesel by using imidazolium-based ionic liquid

Corrosion of biodiesel-filled fuel tanks has become a major problem in the use of biodiesel as a new green energy source. The ionic liquid 1-Hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C₁₀H₁₉N₂]⁺[C₂F₆NO₄S₂]⁻ was used to control corrosion of C-steel in non-edible biodiesel to resolve this problem. The anti-corrosion and antioxidant properties of the [C₁₀H₁₉N₂]⁺[C₂F₆NO₄S₂]⁻ were characterized using weight loss, electrochemical impedance spectroscopy, total acid number measurements beside SEM and EDX analysis. The findings show that [C₁₀H₁₉N₂]⁺[C₂F₆NO₄S₂]⁻ plays an important role in preventing C-steel corrosion in biodiesel with an efficiency close to 99 percent. The adsorption capability and antioxidant properties of [C₁₀H₁₉N₂]⁺[C₂F₆NO₄S₂]⁻ are the major contributors to the ionic liquid's anti-corrosion properties. We anticipate that this work will help to sustainable expand the use of biodiesel as a renewable energy source.

Molecular modelling of compounds used for corrosion inhibition studies: a review

Molecular modelling of organic compounds using computational software has emerged as a powerful approach for theoretical determination of the corrosion inhibition potential of organic compounds. Some of the common techniques involved in the theoretical studies of corrosion inhibition potential and mechanisms include density functional theory (DFT), molecular dynamics (MD) and Monte Carlo (MC) simulations, and artificial neural network (ANN) and quantitative structure-activity relationship (QSAR) modeling. Using computational modelling, the chemical reactivity and corrosion inhibition activities of organic compounds can be explained. The modelling can be regarded as a time-saving and eco-friendly approach for screening organic compounds for corrosion inhibition potential before their wet laboratory synthesis would be carried out. Another advantage of computational modelling is that molecular sites responsible for interactions with metallic surfaces (active sites or adsorption sites) and the orientation of organic compounds can be easily predicted. Using different theoretical descriptors/parameters, the inhibition effectiveness and nature of the metal-inhibitor interactions can also be predicted. The present review article is a collection of major advancements in the field of computational modelling for the design and testing of the corrosion inhibition effectiveness of organic corrosion inhibitors.

Synthesis and structures of divalent Co, Ni, Zn and Cd complexes of mixed dichalcogen and dipnictogen ligands with corrosion inhibition properties: experimental and computational studies

The structural and corrosion inhibition properties of four different transition-metal complexes of heteroleptic S-donor atom dithiophosphonate and N-donor atom phenanthroline ligands are reported. Full structural characterization of the Co, Ni, Zn and Cd complexes was achieved with the aid of single-crystal X-ray crystallography. Structural elucidation revealed the formation of a 4-coordinate Zn(ii) complex, and 6-coordinate Ni(ii) and Cd(ii), as well as a novel dithiophosphonato Co(ii) complex. The ability of the complexes with this ligand type to act as inhibitors of mild steel corrosion in 1 M HCl solution is reported for the first time. Corrosion inhibition potentials of the complexes were assessed using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and density functional theory (DFT). The open circuit potential (OCP) time profile showed the system achieved a steady-state potential before the first 600 s after submerging the working electrode in the corrosive medium. The studied metal complexes are good inhibitors of mild steel corrosion in 1 M HCl and were found to retard the corrosion rate by forming an adsorbed pseudocapacitive film on the steel surface. The order of inhibition efficiencies was in the order Ni (94.14%) > Cd (92.28%) > Zn (91.14%) > Co (72.53%).