Syzygium polyanthum (Wight) Walp. leaf extract as a sustainable corrosion inhibitor for carbon steel in hydrochloric acidic environment

This study focuses on an investigation of the corrosion inhibition behavior of Syzygium polyanthum (Wight) Walp. leaf extract (SPWE) of carbon steel in 1.0 M hydrochloric acid medium. Electrochemical methods demonstrated a corrosion inhibition efficiency of 94.65 ± 0.94 % when 2000 ppm extract is added to the corrosive solution. Furthermore, surface analysis results indicated that with the absence of an inhibitor, the steel surface suffered severe corrosion, while the corrosion density was slow, and a film was observed on the surface after applying the SPWE into a corrosive environment. The film formed by the chemical and physical adsorption of compounds such as polyphenol, flavonoid, alkaloid, and tannin onto the carbon steel surface has been qualitatively and quantitatively analyzed in this study. Notably, increased immersion time and reaction temperature led to significant desorption of molecules, reflecting characteristic of physical adsorption. However, the corrosion inhibition efficiency of SPWE remained effective, particularly within the temperature range of 25–35 °C. Therefore, this study provides an efficient inhibitor for carbon steel corrosion in 1.0 M hydrochloric acidic environment that could be possibly added to the corrosion inhibitor system.