Quinazolinone derivatives as suitable mitigator for corrosion inhibition of carbon steel in hydrochloric acid environment.

The corrosion inhibition behavior of carbon steel (CS) in 1.0 M HCl in the presence of 4-(2-(4-oxo-3-phenyl-3,4-dihydroquinazolin-2-yl) vinyl) phenyl benzenesulfonate (4-OPB) and4-(2-(3-(4-hydroxyphenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)vinyl)phenyl benzenesulfonate (4-HPB) was investigated through chemical evaluation via weight loss (WL) measurements, as well as electrochemical techniques, including AC impedance (EIS), and potentiodynamic polarization (PDP). The inhibition efficiency (IE) increased progressively with higher concentrations of the tested compounds and with temperature elevation, reaching a maximum of 93.2% and 90.1% at 21 × 10⁻3 M of 4-HPB and 4-OPB, respectively from WL tests at 25C. In the other hand, it reached 96.5%, 95.9% for 4-HPB and 4-OPB at 45oCand the same concentration, respectively. The findings indicated that these compounds adhere on the CS surface and create a protective film whose formation conforms to the Langmuir adsorption isotherm, consistent with chemisorption, as supported by the relatively high adsorption energy values (ΔG°ads < - 46 kJ mol⁻1), rise in % inhibition by raising the temperature and the lowering in activation energy (E*) in presence of inhibitors than in its absence. These chemical compounds function as mixed-type inhibitors, according to PDP studies. Surface characterization of the inhibited CS using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) demonstrated significant improvement in surface morphology. The collective results from all employed techniques exhibited strong agreement, validating the inhibitory performance of the studied compounds.