Exploring deep insights into the interaction mechanism of a quinazoline derivative with mild steel in HCl: electrochemical,DFT, and molecular dynamic simulation studies

A novel quinazoline derivative, 3-cyclopropyl-3,4-dihydroquinoline-2(1H)-One (CPHQ), was successfully designed and synthesized. Then, its corrosion inhibition behavior on carbon steel (CS) surface in 1.0?M HCl at different temperatures was investigated using chemical, electrochemical and theoretical techniques. The experiments confirmed that the studied inhibitor shows inhibition efficiency as high as 95% even at very low concentration of 5?×?10^?3 M. To ascertain the nature of adsorption of CPHQ molecules on CS surface, Langmuir adsorption isotherm model was best fitted. From potentiodynamic polarization (PDP) calculations, it was concluded that the CPHQ acted as a mixed type corrosion inhibitor. Electrochemical impedance spectroscopy (EIS) studies revealed that increase in CPHQ concentration, resulted in an increase in the polarization resistance with a simultaneous decrease in the double-layer capacitance values. PDP tests were also performed to understand the corrosion behavior of CS as a function of temperature without and with varying concentrations of CPHQ, at temperatures 303, 313, 323, and 333?K. It can be concluded that the corrosion inhibition effect was dependent on the concentration of the inhibitor and the solution temperature. In order to understand the basic insights of the action mode of CPHQ molecules, Density Functional Theory (DFT) method, and Molecular Dynamic (MD) simulations were also employed on the optimized structure of CPHQ.     

Theoretical Prediction and Experimental Study of Benzimidazole Derivate as a Novel Corrosion Inhibitor for Carbon Steel in 1.0 M HCl

Protection of Metals and Physical Chemistry of Surfaces - The inhibiting effect of benzimidazole derivate (DBI) on corrosion of carbon steel (CS) at temperature range of 303–333 K was...     

Novel Natural Based Diazepines as Effective Corrosion Inhibitors for Carbon Steel in HCl Solution: Experimental,Theoretical and Monte Carlo Simulations

Three new heterocyclic diazepines (CC–diCl, CC–Cl and CC–F) were synthesized for the first time from the natural product curcumin and evaluated as non-toxic corrosion inhibitors for carbon steel (CS) in 1 M HCl. The evaluation was carried out using electrochemical impedance spectroscopy, polarization curves (PDP) measurement, weight loss (WL) and scanning electron microscopy studies. The molecular modeling methods: density functional theory calculations and Monte Carlo simulations were performed to obtain a good insight into the inhibition process. Results obtained from electrochemical techniques and WL tests revealed that, the studied diazepines were effective corrosion inhibitors for CS in the tested medium. Among the evaluated diazepines, CC–diCl showed the highest efficiency. According to the PDP results, the diazepines behaved as mixed-type (cathodic and anodic) inhibitors. A complete thermodynamic study was also performed on the diazepine with the highest efficiency CC–diCl to gain a better understanding of the inhibition process. The adsorption of the diazepines onto CS surface obeyed a Langmuir adsorption isotherm. A good correlation was obtained between the molecular modeling studies and inhibition efficiency (IE%) of the tested diazepines.     

Advanced quantum chemical and electrochemical analysis of ravage drugs for corrosion inhibition of mild steel

The blocking of corrosive sites of soft (mild) steel has been studied using ravage drugs Pyrazinamide (Z), Isoniazid (H) and Rifampicin (R) in 0.5?M HCl medium. The degree of ability of these drugs to act as corrosion controlling agents was investigated by gravimetric measurements, potentiostatic polarization and electrochemical impedance spectroscopy. Their inhibition efficacy has, further been validated through theoretical and simulation studies. Though, all the drugs have shown good anticorrosive impact, but, rifampicin (R) has proven its greater efficacy as 97.06% at 1000?ppm and at 303?K. Polarization curves depict that the H and R drugs act through mixed mode of inhibition while Z drug is predominantly anodic in nature. The result of electrochemical impedance spectroscopy specifies that the corrosion reaction is resisted by charge transfer process. Morphology of un-corroded and corroded coupons was studied by scanning electron microscopy. The mechanism of adsorption is obeyed well through Langmuir isotherm and advocated a significant physiochemical type of interaction by the compounds on the metal surface. Thus, all the findings got via various experimental techniques along with that of obtained using Molecular Dynamics (MD) and Density Functional Theory (DFT) for the three compounds are in proper harmony.