The corrosion inhibition behavior of polyaniline nanoparticles (nPANI) doped with dodecyl benzene sulfonic acid (DBSA) as a dispersed phase in hydrochloric acid (HCl) solution on stainless steel 316 (SS316) has been studied using potentiodynamic polarization, electrochemical impedance spectroscopy and capacitance measurements (Mott–Schottky approach). The results show that the passive film formed in the nPANI solution has lower donor density and larger impedance than the passive film formed in the DBSA solution, which is attributed to the adsorption nature of nPANI and its ion-exchange properties. The adsorption of the studied compounds on the stain steel surface follows the Langmuir adsorption isotherm. The surface analyses were evaluated with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Quantum chemical parameters correlate well with the experimental results, which support higher inhibition efficiencies of PANI due to the high ability of electron-donating of benzenoid and quinoid rings. Additionally, based on Monte Carlo and molecular dynamics simulations, the magnitudes of adsorption energies also correspond to experimental inhibition efficiency results.

Keywords