Anticorrosive potential of Garcinia mangostana L. peel extracts-doped hybrid sol-gel films on low carbon steel in salty water

This study investigates the corrosion inhibition potential of Garcinia mangostana peel extracts using ethanol (MPE) and water (MPW) as corrosion inhibitors for low carbon steel in aqueous 3.5 wt.% NaCl. To ensure the purity of MP extracts, complementary spectroscopy techniques such as FT-IR, NMR, and TGA were adopted to characterize their structure as well as phytochemical analyses. MPE extract exhibited higher total phenolic content, total flavonoid content, total condensed tannin content, and antioxidant activity compared to MPW. Hybrid sol-gel matrices were synthesized using APTES and TEOS silanol precursors, where prepared films were applied via dip-coating. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) studies revealed that 50 ppm MPE-doped hybrid sol-gel coating achieved the highest inhibition efficiency (81.64%), followed by 75 ppm MPW-doped sol-gel coating (73.87%). Both extracts incorporated coating systems rendered mixed-type corrosion protection, predominantly influencing the cathodic reaction. SEM analysis surfaced an improvement in the surface morphology of low carbon steel in the presence of both inhibitors. The projected corrosion inhibition mechanism has also been discussed regarding anticorrosion behavior. Hence, the present work affords a value-added application by exploiting mangosteen peel as a waste material towards potential anticorrosion applications.