A combined computational and experimental study on the mild steel corrosion inhibition in hydrochloric acid by new multifunctional phosphonic acid containing 1,2,3-triazoles

Two triazole derivatives with phosphonic acid as pendent group, namely [3-(4-phenyl-[1–3]triazol-1-yl)-propyl]-phosphonicaciddiethylester (PTP) and [3-[4-(4-dimethylamino-phenyl)-[1–3]triazol-1-yl]-propyl]-phosphonic acid diethylester (DMPTP) were synthesized and fully characterized using NMR spectroscopy, Mass spectrometry, Infra-Red (FT-IR) spectroscopy and elemental analysis. The synthesized multifunctional heterocycles were investigated to inhibit the corrosion of mild steel in acidic solution HCl (1 M) by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and weight loss measurements. The results of the different corrosion measurement techniques are in good agreement. The potentiodynamic polarization analysis shows that the PTP and DMPTP derivatives are mixed-type inhibitors. In addition, EIS measurements were used to simulate the corrosion inhibition process by using a suitable equivalent circuit. The thermodynamic and kinetic parameters obtained demonstrated that both inhibitors adsorb to the surface of mild steel according to the Langmuir model’s isotherm. A layer adsorbed onto the surface of the mild steel has been confirmed by FT-IR, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) techniques. Moreover, Density Functional Theory (DFT) analysis and Molecular Dynamics simulations (MD) have been carried out, the computational results agreeing with the experimental ones.