Synthesis, characterization and electrochemical behavior for API 5L X70 carbon steel in 5% sulfamic acid medium using PVVH/PEMA blend filled with gold nanoparticles

In the present work, we synthesized the polymer blend of Poly (vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate), and Poly (ethyl methacrylate) (PEMA) by solution casting method and then filled it with different concentrations of gold nanoparticles (Au-NPs). The present composite was employed as corrosion inhibitors for API 5L X70 carbon steel in 5% sulfamic acid solution by electrochemical methods such as potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) techniques. The quantum chemical computations utilized by DFT process produced an acceptable theoretical interpretation for the adsorption and inhibition performance of the composite on the carbon steel surface. PP plots demonstrated that the examined samples act as a miscellaneous type inhibitor. With raising its concentrations, the inhibition productivity rises up to 91.3% in case of blend/ 3% AuNPs as observed from the EIS results. The inhibition mechanism follows Langmuir adsorption isotherm. It was discussed as concerns the nanocomposite investigated adsorption on steel metal surface and confirmed using SEM. Bode plots exposed that, the total impedance elevated with raising examined polymer concentration and the constant addition to the phase angle move was clearly associated with the increasing of the examined polymer concentration adsorbed on carbon steel species. A significant agreement was attained among the quantum chemical variables (DFT and Mulliken atomic charges) and the experimental computations, indicating the efficiency of the nanocomposite to act as effective corrosion inhibitor.