A critical view of the QSAR model for the prediction of a new bispyrazole derivative BPYR-P as a corrosion inhibitor for 304 SS in a 1.0 M HCl solution

Abstract

Using the potentiodynamic polarization (PDP) technique, a set of seven newly synthesized bispyrazole derivatives (PYR-1 to PYR-7) were examined as corrosion inhibitors for 304 stainless steel (304 SS) in 1.0 M HCl solutions at different concentrations (10−13 to 10−5 M). The experimental results were used to create a predictive model for the anticorrosion properties of another inhibitor (BPYR-P) within the same family. The model was created by relating various physicochemical descriptors of the seven bispyrazol inhibitors to their experimental inhibitory efficiency using the quantitative structure-activity relationship (QSAR) methodology along with the genetic function approximation (GFA) technique. The predicted inhibition efficiency was validated by several electrochemical techniques, including electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP). The predicted QSAR values for BPYR-P showed good agreement with experimental data, establishing the reliability of the model in predicting the inhibitor's performance. The BPYR-P acts as an excellent corrosion inhibitor for 304 SS in a 1.0 M HCl solution, and its inhibition efficiency increases with the increase in concentrations. The double-layer capacitance (Cdl) decreases and the charge transfer resistance of 304 SS increases as the BPYR-P concentrations increase. The adsorption of predicted BPYR-P on a 304 SS surface displayed mixed-type inhibitor and obeyed the Langmuir adsorption isotherm. AFM, SEM-EDX, UV–visible spectra, contact angle measurement, XRD, parameters derived from quantum chemical calculations (DFT) and molecular dynamic simulations (MD) were in good agreement with the experimental data obtained.