Electrochemical and thermodynamic studies of N-(phenol-p-ylmethylene)-2-amino-5-ethyl-1,3,4-thiadiazole as corrosion inhibitor complemented with theoretical investigations

Hydrochloric acid is an important mineral acid that is widely used in a variety of applications, including well acidification, water treatment, chemical cleaning, and acid pickling (HCl).Preventing corrosion of metal buildings has aroused much interest due to the huge financial and safety losses that corrosion has caused in many industries.Mild steel is an important structural material in a variety of industries because it is widely used owing to its low cost and excellent physical and mechanical properties.This study looked at the corrosion inhibitory properties of N-(phenol-p-ylmethylene)-2-amino-5-ethyl-1,3,4-thiadiazole (PAT) for mild steel in 1 M HCl.The anticorrosion efficacy of PAT as an inhibitor was studied using a variety of electrochemical techniques (electrochemical impedance spectroscopy and potentiodynamic polarization).For the studied inhibitor, the greatest inhibition efficiency was observed at an optimal dose of 0.5 mM.The thermodynamic behavior was studied at various temperatures.As a result, the experiment demonstrated that increasing the temperature reduces inhibitor efficiency and increases the corrosion rate.The experiment discussed the effect of temperature in the range of 30, 40, 50, and 60°C on the corrosion inhibitor and showed that the corrosion rate increased from 7.6 to 630.4 mpy.Furthermore, quantum chemistry calculations using density functional theory (DFT) were used to investigate the relationship between inhibition efficacy and inhibitor molecule structure.All of the calculated results agree with the experimental findings.