Evaluation of Vitis vinifera seed oil as a green corrosion inhibitor for high-carbon steel and ferrovanadium alloys in sulfuric acid

The corrosion inhibition performance of Vitis vinifera seed oil (VVSO) was investigated on high-carbon steel (HCS) and ferrovanadium (FV) alloy in 0.25 M H₂SO₄ solution using gravimetric, potentiodynamic polarization, open circuit potential (OCP) measurements and optical microscopy. Gravimetric studies revealed superior inhibition efficiency on HCS, where corrosion rates decreased progressively with increasing VVSO concentration, reaching 95% efficiency at 0.5% VVSO after 360 hours of exposure. In comparison, FV alloys exhibited moderate inhibition, peaking at 73.95% at 2% VVSO. Potentiodynamic polarization results confirmed mixed-type inhibition behavior, with significant reductions in corrosion current density for HCS, correlating with efficiencies exceeding 70%. Conversely, for FV alloys, the highest inhibition efficiency of 72.95% was recorded at 2% VVSO, suggesting adsorption saturation at higher concentrations. Open circuit potential studies highlighted shifts to less negative potentials, indicative of enhanced corrosion resistance. For HCS, stabilization occurred around -0.490 V at 0.5% VVSO, forming a protective layer, while for FV, the potential stabilized at -0.495 V at 3% VVSO, demonstrating uniform inhibitor adsorption and reduced anodic dissolution. Overall, VVSO demonstrated concentration-dependent inhibition, exhibiting superior protection on HCS and moderate efficacy on FV as evident in the difference between the optical images of the inhibited and non-inhibited alloy surfaces. The findings underscore the potential of VVSO as an eco-friendly and effective corrosion inhibitor, with optimal performance influenced by substrate material and inhibitor concentration.