Evaluation of Phytochemical, Polyphenol Composition and Anti-corrosion Capacity of Cucumis anguria L. Leaf Extract on Metal Surface in Sulfuric Acid Medium

Cucumis anguria L. (C. anguria L.) commonly known as Indian gherkin is originally from Africa, though now seen widely in southeast, northeast and north of Brazil. The leaf was examined for phytochemicals and its role in inhibiting corrosion of mild steel in 1 M H2SO4. The phytochemical quantification of total phenols (TPC) (89.32 mg/g), total flavonoid (TFC) (35.88 mg/g), tannins (8.99 mg/g) and steroids (18.21 mg/g) were identified. A detailed analysis of phenolic constituents had shown the presence of significant amount of myricetin (358.54 mu g/g), quercetin (294.25 mu g/g), salicylic acid (288.21 mu g/g), chlorogenic acid (252.31 mu g/g) and kaempferol (201.01 mu g/g). This interesting identification paved way taking an initiative for finding the anticorrosive nature of the extract through electrochemical and non-electrochemical (weight loss) studies. The weight loss study highlighted a significant change in weight when incubated at 330 +/- 1 K with inhibitor (250 ppm) than without inhibitor providing us an optimum concentration of inhibitor. Later the surface analysis was made using Raman, XRD, SEM-EDX and AFM. Raman spectroscopy confirmed the existence of a protective film created by C. anguria L. leaf extract on metal surface (mild steel). The maximum inhibition efficiency of 92.39% was reached using 250 ppm of the C. anguria L. leaf extract inhibitor.