A green complex film based on the extract of Persian Echium amoenum and zinc nitrate for mild steel protection in saline solution; Electrochemical and surface explorations besides dynamic simulation

• Published in: Journal of molecular liquids 2019-10, Vol.291, p.111281, Article 111281
• Main Authors: Tabatabaei majd, Mehdi, Bahlakeh, Ghasem, Dehghani, Ali, Ramezanzadeh, Bahram, Ramezanzadeh, Mohammad
• Format: Article
• Language: English
• Subjects: AFM; Corrosion; GIXRD; Hybrid film; MD/MC/Quantum mechanics
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2019.111281

This study introduces a novel and effective inhibition system based on Persian Echium amoenum (PEA) and zinc nitrate for mild steel protection in 3.5 wt% NaCl solution. The functional groups and complexes in the structure of PEA and PEA:Zn containing solutions were surveyed by UV–Vis analysis. The composition and morphology examination of surficial films were carried out by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), atomic force microscope (AFM), nuclear magnetic resonance spectroscopy (NMR), grazing incidence X-ray diffraction (GIXRD) analysis, and static contact angle (CA) measurements. Electrochemical impedance spectroscopy (EIS) and potentiodynamic spectroscopy (PDS) were carried out to study the performance of each PEA:Zn ratios and understand the mechanism of inhibition. Moreover, the computational studies were utilized to have a better conception from the mechanism of chelation. Results of electrochemical analyses showed that the 200 ppm PEA +600 ppm Zn sample has the highest performance and efficiency (95%). Moreover, the electronic-scale quantum mechanics (QM) computations proposed the donor-acceptor interactions of inhibiting species with the metallic surface. This means that the protective PEA-Fe-Zn complexes have been formed through the injection of the lone pair electrons of organic structures into the empty d-orbitals of the metallic ions of Zn and Fe. [Display omitted] •A novel hybrid complex film based on PEAZn2+ was developed on mild steel surface.•600 ppm PEA + 200 ppm Zn sample showed 91% efficiency in 3.5 wt% saline media.•The QM results proposed the donor-acceptor interactions of inhibitors with metal.