Akebia trifoliate koiaz peels extract as environmentally benign corrosion inhibitor for mild steel in HCl solutions: Integrated experimental and theoretical investigations

[Display omitted] •Eco-friendly pectin components were extracted from akebia trifoliate koiaz peels.•The extract showed 90% inhibition efficiency for mild steel corrosion in HCl medium.•Electrochemical investigations suggest a protective barrier formation at the solution/steel interface.•Adsorption of inhibitor on the steel surface follows the Langmuir isotherm.•Molecular simulation was used for interpreting the inhibition phenomena. In this account, pectin components were obtained from akebia trifoliate koiaz peels with the acid extraction technology. The chemical constituent of the akebia trifoliate koiaz peels extract (ATKPE) was analyzed and its anti-corrosion performance for mild steel in HCl medium was investigated by electrochemical methods, surface analysis and theoretical calculations. Experimental results show that ATKPE exhibits excellent corrosion inhibition characteristic, and its inhibition efficiency can be as high as 90% when the concentration of ATKPE is 800 mg/L. Electrochemical measurements show that ATKPE is a mixed-type corrosion inhibitor consisting with Langmuir adsorption model. In addition, SEM, AFM and contact angle observations suggests that the ATKPE may attach firmly to the metal surface by forming a barrier film. XPS and ATR-FTIR results further verify the bonding interaction between the functional groups and steel substrate. Meanwhile, quantum chemical calculations and molecular dynamics (MD) simulations were performed to reveal the inhibition mechanism at molecular/atomic level. In brief, our findings demonstrate a novel environmentally benign, efficient corrosion inhibitor for steel protection in acidic media.