Insights into the corrosion resistance of a novel quinoline derivative on Q235 steel in acidizing medium under hydrodynamic condition: experimental and surface study

The study concentrated on the fabrication of an environmentally friendly inhibitor, namely ethyl 4-(4-methoxyphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate derivative of quinoline (MQC), in a single step, and assessed its inhibiting property in highly acidic fluid (15 % HCl) for protecting Q235 steel at 1500 rpm rotation speed. Weight reduction, Potentiodynamic polarization, and electrochemical impedance spectroscopy were utilized in the study to investigate the inhibiting impact of MQC. The estimated findings corroborated the inhibiting data of 93.54 and 98.38 % at 308 K with 100 mg/L/only MQC and MQC + KI/75 mg/L + 0.5 mM, respectively, and the impact of temperature upon the inhibitory capability possessed little impact at larger dose quantities. According to the electrochemical outcomes, the MQC is a mixed-type corrosion inhibitor. The findings of the SEM, EDX, and AFM examinations demonstrated that the MQC established a barrier over the surface of Q235 steel by adsorption, changing the hydrophilic and hydrophobic attributes of the Q235 steel surface. An additional XPS assessment demonstrated MQC molecule adsorption on the Q235 steel surface. Density functional theory (DFT) and molecular dynamic simulations (MD) calculations were further performed to justify the experimental results.