Resumo

OYEWOLE, Olamide; ADEOYE, John Busayo; TUNBOSUN, Abayomi  e  CELESTINE, Chukwuma Chukwuemeka. Optimization and Performance Evaluation of Lemon Leaves Extract as Inhibitor for Mild Steel Corrosion in a 1.0 M HCl Solution. Port. Electrochim. Acta [online]. 2023, vol.41, n.6, pp.409-424.  Epub 31-Dez-2023. ISSN 0872-1904.  https://doi.org/10.4152/pea.0602.

This study examined the use of LLE as an inhibitor for MS in a HCl medium, using the optimization approach. In order to determine the metabolites presence, phytochemical analyses were performed on the plant extract. Three variables factors were considered for the optimization: inhibitor C (0.2- 0.8 g/L); T (30-50 ºC); and time (2-6 h). Morphological structure was determined using SEM. Phytochemical analysis results showed the presence of saponins, alkaloids and flavonoids, which confirmed the extract as a good inhibitor. The optimal process conditions were T of 48.30 ºC, time of 2.49 h and C of 0.66 g/L, for obtaining the highest IE of 84.2 %. Meanwhile, the validated OPL gave an IE of 85.6 %. The results observed from SEM showed that a more protective film was formed on the MS surface, in the validated process level. LLE adsorption obeyed Langmuir’s isotherm, and the thermodynamic parameters were: ∆Gads (-17.05, -18.74 and -15.35 kJ/mol-1) and ΔH (41.73, -15.41 and -1.58 kJ/mol-1). ∆Gads negative values indicated LLE spontaneous adsorption, which was physisorption. It can be concluded that LLE would be recommendable as a low-cost inhibitor for MS corrosion in 1 M HCl.

Palavras-chave : corrosion; inhibition; LLE; SEM; optimization; phytochemical analyses; RSM.

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