Rapeseed cake meal extract as an efficient plant-based inhibitor for the corrosion of steel in Cl2CHCOOH: Experiments and molecular modeling calculations

In alignment with the principles of environmentally sustainable practices, the inhibition mechanism of rapeseed cake meal extract (RCME) on steel in dichloroacetic acid (Cl 2 CHCOOH) was investigated through the combination of experimental methodologies and molecular modeling calculations. The results indicate that RCME achieves a peak inhibition efficiency of 92.3 % in 0.10 M Cl 2 CHCOOH at 40 °C. The adsorption of steel surfaces is consistent with Langmuir adsorption isotherm, which includes both physical and chemical adsorption processes. Theoretical simulations show that amino acids and purine compounds in RCME contain active centers that facilitate the creation of chemical bonds with Fe atoms, thereby collectively exerting inhibitory performance. When these two types of compounds interact in 1:9 ratio within RCME, reduced free volume fraction is observed, effectively diminishing the diffusion rate and mobility of corrosive ions. Microscopic morphological analyses conducted using metallographic microscopy, SEM, AFM, and CLSM reveal noteworthy diminishment in the corrosion degree of steel surface after the introduction of RCME. XPS and TOF-SIMS provide evidence that carbon, nitrogen, and oxygen elements present in RCME can form bonds with Fe atoms. RCME functions as a mixed inhibitor in Cl 2 CHCOOH with the electrochemical inhibition mechanism of "active site blocking effect". Following the incorporation of RCME, charge transfer resistance rose, efficiently inhibiting the occurrence of electrochemical corrosion reactions. • Rapeseed cake meal extract (RCME) is an effective inhibitor for steel in Cl 2 CHCOOH. • L-lysine and adenine synergistically function as active ingredients in RCME. • SEM, AFM and CLSM show that RCME effectively inhibits corrosion of steel surface. • XPS and TOF-SIMS analysis indicate that RCME can form chemical bonds with iron atoms. • RCME functions as a mixed inhibitor that controls the "active site blocking effect".

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