Investigative Study of Corrosion Inhibition of Newbouldialeavis is Extracts on Mild Steel in 1M NaOH and KOH Solutions


Authors : J. J. O. Ajali; V.E. Ojukwu; O. E. Achugbu; C. C. Ejiofor; C. N. Onyenanu; L.N. Emembolu; J.T. Nwabanne

Volume/Issue : Volume 8 - 2023, Issue 6 - June

Google Scholar : https://bit.ly/3TmGbDi

Scribd : https://tinyurl.com/53sjysv3

DOI : https://doi.org/10.5281/zenodo.8150009

Abstract : The corrosion inhibition of Newbouldialeavis (NL) leaf extract on mild steel in alkaline media was investigated in this study. The plant leaf extract's functional groups comprise of oxygen and nitrogen atoms (O-H, N-H, C-N, C-O, C=O, and CN) as well as aromatic rings, according to FTIR data.Phytochemical analysis showed the presence of tannins, saponins, phytates, phenolics, flavonoids, cardiac glycosides and alkaloids. The results also showed that mild steel exhibits a considerable shift to passivation within the examined potential range. The inhibitors' molecules created an excellent protective coating on the mild steel, according to SEM micrographs. Adsorption of plant extracts on metal surfaces was spontaneous and occurred via the physical adsorption process.The measurements of gravimetric, thermometric, potentiodynamic polarization and electrochemical impedance spectroscopy results showed that the inhibition efficiency rose with increasing concentration of inhibitors and decreased with increasing temperature. The findings of the potentiodynamic polarization indicated that the plant leaf extracts were mixed-type inhibitors because Ecorr value greater than 85mV confirms that the NL extract is a mixed-type inhibitor. The findings of electrochemical impedance spectroscopy demonstrated that adding inhibitors enhanced the charge-transfer resistance of the corrosion process and hence the inhibition performance. The inhibition effiency (IE%) in the presence of 200mg/l and 1000mg/l of NL inhibitor was gotten to be 71.2% and 87.9% respectively for 1M KOH medium and 95.6% and 97.1% respectively for 1M NaOH medium. Quantum chemical parameters indicated that the inhibitor molecules' active ingredients slowed the corrosion of mild steel as was confirmed by density functional theory.

Keywords : Alkaline corrosion, electrochemical impedance spectroscopy, Density Functional Theory (DFT), potentio dynamic polarization or quantum chemical calculations.

The corrosion inhibition of Newbouldialeavis (NL) leaf extract on mild steel in alkaline media was investigated in this study. The plant leaf extract's functional groups comprise of oxygen and nitrogen atoms (O-H, N-H, C-N, C-O, C=O, and CN) as well as aromatic rings, according to FTIR data.Phytochemical analysis showed the presence of tannins, saponins, phytates, phenolics, flavonoids, cardiac glycosides and alkaloids. The results also showed that mild steel exhibits a considerable shift to passivation within the examined potential range. The inhibitors' molecules created an excellent protective coating on the mild steel, according to SEM micrographs. Adsorption of plant extracts on metal surfaces was spontaneous and occurred via the physical adsorption process.The measurements of gravimetric, thermometric, potentiodynamic polarization and electrochemical impedance spectroscopy results showed that the inhibition efficiency rose with increasing concentration of inhibitors and decreased with increasing temperature. The findings of the potentiodynamic polarization indicated that the plant leaf extracts were mixed-type inhibitors because Ecorr value greater than 85mV confirms that the NL extract is a mixed-type inhibitor. The findings of electrochemical impedance spectroscopy demonstrated that adding inhibitors enhanced the charge-transfer resistance of the corrosion process and hence the inhibition performance. The inhibition effiency (IE%) in the presence of 200mg/l and 1000mg/l of NL inhibitor was gotten to be 71.2% and 87.9% respectively for 1M KOH medium and 95.6% and 97.1% respectively for 1M NaOH medium. Quantum chemical parameters indicated that the inhibitor molecules' active ingredients slowed the corrosion of mild steel as was confirmed by density functional theory.

Keywords : Alkaline corrosion, electrochemical impedance spectroscopy, Density Functional Theory (DFT), potentio dynamic polarization or quantum chemical calculations.

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