الفهرس 
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Abstract
The present study investigates the effect of selected new nano-pyrazole derivatives (BPYR-Ps) on the corrosion inhibition of 304 stainless steel in the absence and presence of different concentrations (10-5, 10-7,10-9 10-11and 10- 13M) of BPYR-Ps inhibitors in a 1.0M HCl solution at 298K.
Measurements were conducted under different experimental conditions using several techniques, chemical techniques (weight loss) and electrochemical techniques including electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP).
The results of EIS indicated that the values of charge transfer resistance and inhibition efficiency tended to increase with higher inhibitor concentrations. This can be attributed to an increase in the thickness of the electrical double lay.
Polarization curves in 1.0M HCl, in the absence and presence of BPYR- Ps derivatives at 298K, indicated that these compounds acted as mixed-type inhibitors. They increased both the anodic and cathodic overpotentials and caused parallel shifts in the position of the Tafel lines in both directions. This suggests that these compounds had no impact on the corrosion mechanism and instead acted as blocking-type inhibitors by simply obstructing the active sites on the 304 stainless steel surface.
The weight loss method at different temperatures (298 −343K) evaluates the corrosion inhibition efficiency of the BPYR-Ps inhibitors, which improved as the inhibitor temperature increased.
The inhibition of corrosion on the surface of 304 stainless steel occurs through the adsorption of the inhibitors. The adsorption behavior of the studied
inhibitors follows the Langmuir isotherm.According to an analysis of typical Gibbs free energies of adsorption, the corrosion inhibition by BPYR-Ps derivatives is related to a process with both physisorption and chemisorption.
The DFT approach was used to calculate quantum chemical characteristics such as the energies of the highest occupied (EHOMO) and lowest unoccupied (ELUMO) molecular orbitals as well as the total energy (Etot). These parameters were obtained after geometric optimization, considering all nuclear coordinates..
To simulate the adsorption of BPYR-Ps derivatives on the Fe (111) surface in a 1.0M HCl, the molecular dynamics simulation technique can be employed.There exists a relationship between the structural properties of the studied inhibitor molecules and their inhibition efficiency. This relationship can be utilized to construct a model using the QSAR model, genetic function approximation (GFA), and neural network analysis (NNA) techniques.The QSAR model is used to predict the corrosion inhibition efficiency for the new nano pyrazole derivatives BPYR-P8, BPYR-P9, and BPYR-P10 (Model Validation). The predicted QSAR values for three inhibitors from the same family, namely BPYR-P8, BPYR-P9, and BPYR-P10, were found to be in good agreement with the experimental data, thus demonstrating the reliability of the suggested model for predicting the QSAR of inhibitors.
The parameters derived from quantum chemical calculations (DFT) and molecular dynamic simulations (MD) were in good agreement with the experimental data obtained from the weight loss method, DC technique, and AC technique.
The creation of a protective layer on the 304 SS surface was confirmed by SEM, EDX, AFM, XRD, static contact angle, and UV–vis analysis.
Finally, the three different electrochemical techniques exhibited similar behavior where, all tested BPYR-Ps derivatives exhibited inhibitory properties against the corrosion of 304 stainless steel in 1.0 M HCl. The inhibitory efficiency of the investigated inhibitors increased with higher concentrations, demonstrating that as the inhibitor concentration increased, the corrosion rate decreased while the inhibition efficiency increased.