Phytochemical screening, total phenolic and flavonoid methanolic extract of pomegranate bark (Punica granatum L): Evaluation of the inhibitory effect in acidic medium 1 M HCl

Abstract The evaluation of the polyphenolic chemical composition in the methanolic extract of Punica granatum L. bark considered as a waste, using phytochemical screening (phenols, flavonoids, saponosides, sterols and polyterpenes), quantitative tests and UV analysis, which indicate an important amount of total phenolic content (272.82 ± 3.05 µg/mg GAE/g sample) while the minor fraction of total flavonoids (38.26 ± 1.78 µg/mg QE/g sample). The inhibition effect of the methanolic extract on the mild steel corrosion in 1 M HCl at 298 K has been investigated using the following tools and methods: electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss measurements. After varying different concentrations of the extract, the optimal inhibition efficiency (88%) was correlated to the concentration of 1 g/L. The adsorption phenomenon of the extract on mild steel surface in acidic medium has been studied showing the follow-up of the Langmuir adsorption model. The polarization curves indicated that the extract might be classified as a mixed type inhibitor. The waste generated by Punica granatum L. bark could be valorized and explored as a very efficient new corrosion inhibitor, eco-friendly to the environment with low cost.