Extracts of curcumin-incorporated hybrid sol–gel coatings for the corrosion mitigation of mild steel in 0.5 M HCl

Curcumin was extracted from turmeric using two solvents (ethanol and water), doped with hybrid (TEOS-APTES) sol–gel coatings for the corrosion protection of mild steel. Characterization of curcumin extracts was carried out using integral analyses, namely FTIR, NMR, DSC, TGA, total phenolic content, and antioxidant assay. Corrosion-inhibitive ability of coatings doped with curcumin extracts (25, 50, 75, and 100 ppm) were evaluated via electrochemical impedance spectroscopy and potentiodynamic polarization measurements. It was evident that sol–gel incorporated with 100 ppm ethanol extract provided more than 90% of inhibition efficiency. Coated mild steel surfaces were characterized using FTIR, SEM/EDX, and water contact angle analysis where coatings incorporated with curcumin extracts were found to be hydrophobic (θ = 100.2°).