The electrochemical behavior of nanocomposite organic coating based on clay nanotubes filled with green corrosion inhibitor through a vacuum-assisted procedure

Abstract

In this study, the clay nanotubes were loaded with green corrosion inhibitor obtained from the basil aqueous extract through a vacuum-assisted procedure. The nanocontainers with long-term inhibitive performance were synthesized and introduced to the alkyd coating for corrosion protection of mild steel substrates against the saline solution. The basil loaded halloysite nanotubes (BHNs) were characterized by thermogravimetric analysis, field emission scanning electron microscopy, ultraviolet–visible spectroscopy, X-ray diffraction (XRD), and Fourier transformation infrared spectroscopy analyses. Results showed that the successful loading of basil molecules in the halloysite nanotubes (HNT) was achieved under vacuum condition. Active corrosion inhibition performance of BHNs was investigated by electrochemical and visual tests in saline solution (NaCl 3.5 wt%). The results of electrochemical impedance spectroscopy (EIS) and polarization tests revealed the considerable inhibitive action of the synthesized nanocontainers in 3.5 wt % NaCl solution. Also, scanning electron microscopy, XRD, and energy dispersion spectrometer results confirmed the deposition of a surface inhibitive film on the samples which dipped in the BHNs extract solution. The corrosion inhibition performance of nanocomposite alkyd coatings based on HNTs and BHNs was investigated by EIS and visual tests. The best corrosion resistance was observed in the presence of 0.5 wt % HNTs in the nanocomposite coating. Also, it was found that BHNs significantly improved the corrosion resistance of nanocomposite organic coating over time. The barrier and active performance of BHNs were proposed as the protective mechanism of nanocomposite coating in the presence of the nanocontainers.