Rapeseed cake meal extract as an eco-friendly green sustainable inhibitor for the corrosion of cold rolled steel in trichloroacetic acid solution.

• Rapeseed cake meal extract (RCME) is an excellent inhibitor for steel corrosion in trichloroacetic acid (TCA) solution with a maximum inhibition efficiency of 92.7 %. • The adsorption of RCME obeys Langmuir isotherm at 20 and 30 °C, Temkin isotherm at 40 °C, and Freundlich isotherm at 50 °C. • RCME acts as a cathodic inhibitor through "blocking effect of active sites". • SEM, AFM, CLSM, XPS, XRD and TOF-SIMS confirm that RCME can strongly adsorb onto the surface of CRS to form a protective film. • QC calculations and MD simulations indicate that the active centers are predominantly located on benzene rings, O- or N-containing heterocyclic rings. The inhibitory properties of rapeseed cake meal extract (RCME) on the corrosion of cold rolled steel (CRS) in trichloroacetic acid (TCA) were systematically investigated using gravimetric, electrochemical, surface characterizations and theoretical calculations. The results demonstrate that RCME exhibits excellent inhibitory performance with a maximum inhibition efficiency of 92.7 % for 100 mg L⁻¹ RCME at 20 °C. The adsorption of RCME obeys Langmuir isotherm at 20 and 30 °C, Temkin isotherm at 40 °C, and Freundlich isotherm at 50 °C. RCME acts as a cathodic inhibitor. The charge transfer resistance is increased with the addition of RCME, while the double-layer capacitance decreases. SEM, AFM, CLSM, XPS, XRD and TOF-SIMS analyses confirm that the active components in RCME adsorb onto the surface of CRS, forming a protective film that effectively inhibits the corrosion of CRS by TCA. Along with the increase in the concentration of RCME, the surface tension of the inhibited solution gradually decreases, while the electrical conductivity increases before stabilizing. HPLC-MS and FTIR analyses reveal rutin, linolenic acid, linoleic acid and adenine are the effective substances in RCME. Quantum chemical (QC) calculations and molecular dynamic (MD) simulations indicate that the active centers of the effective inhibitor molecules are predominantly located on benzene rings, O- or N-containing heterocyclic rings, and functional groups such as C=O and C=C. Additionally, their main chains adsorb onto the Fe (001) surface in an approximately flat manner, involving both chemical and physical adsorption processes. [Display omitted] [ABSTRACT FROM AUTHOR]