Phenolic fraction of Ammi visnaga extract as environmentally friendly antioxidant and corrosion inhibitor for mild steel in acidic medium

The present study aims to prepare a phenolic extract of Ammi visnaga from its areal part and qualitative measurement of flavonoids and tannins present in the extract using Folin Ciacalteu and Quettier-Deleu methods. Antioxidant activities of different fractions of the extract was measured using DPPH^•, FRAP, β-carotene and total antioxidant capacity techniques. The n-butanol and ethyl acetate fractions designated as F3 and F6, respectively. Corrosion inhibition effect of quercetin and catechin and F3 and F6 was studied for mild steel in 1 M HCl using electrochemical procedures. Electrochemical studies showed that quercetin and catechin standards showed antagonistic effect towards mild steel acidic corrosion. Among the tested species, the F6 and F3 fractions showed highest efficiencies of 93% and 88%, at 0.15 g L⁻¹ concentration, respectively. Potentiodynamic and electrochemical impedance spectroscopy (EIS) studies showed that tested species act as mixed-type corrosion inhibitors, respectively. Adsorption of catechin on metallic surface in acidic medium obeyed the Temkin and El-Awady models.