Computational, kinetic, and electrochemical studies of polyaniline functionalized ZnO and ZnO-SiO2 nanoparticles as corrosion protection films on carbon steel in acidic sodium chloride solutions

Abstract

Two novel nanocomposites based on polyaniline functionalized ZnO and ZnO-SiO2 nanoparticles (ZnO@PANi and ZnSiO@PANi) were synthesized, characterized, and evaluated as protective films for steel pipelines in the pickling process at 25–55 °C. The prepared nanocomposites were described using different spectroscopic characterization methods including UV–vis, FTIR, DLS, XPS methods, and other physicochemical techniques including XRD, FESEM, and HR-TEM. The novelty of these films is in the fact that the ZnO and ZnO-SiO2 nanoparticles are functionalized by polyaniline which is electrochemically stable in acidic solution and has high conductivity. Electrochemical systems such as open circuit potentials (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) were utilized to attain the kinetics and mechanistic findings of the corrosion protection route. The outcomes indicate that the two fabricated ZnO@PANi and ZnSiO@PANi are efficient acidic corrosion inhibitors. The protection performance of ZnSiO@PANi (98.6%) was more pronounced at a dose (150 mg/L) than ZnO@PANi (92.3%) and individual PANi (83.4%) as achieved from PDP findings. The effect of temperature and flowing conditions reinforces further the performance of both nanocomposites. Surface characterization using FESEM/EDS delivered more indication for the steel surface protection with the ZnO@PANi and ZnSiO@PANi nanocomposites. Molecular modeling using DFT calculations and MC simulations supported the experimental findings. The binding energies of the compounds and Fe interface follow the order of ZnO@PANi > ZnSiO@PANi, which is in good agreement with the empirical results. An important suggestion of these results is the probability of substituting traditional toxic small molecules with cost-effective and non-toxic polymeric nanocomposites as protective films for use in the oil and gas industry.