Dandelion (Taraxacum officinale) Root Extract as a Green Corrosion Inhibitor of Steel in 3% NaCl

This study investigates the potential of dandelion (Taraxacum officinale) root ethanol extract as a green corrosion inhibitor for two types of steel (TH-550 and TS-275) in a chloride-rich environment. Steel samples were chemically prepared and immersed in a 3% NaCl solution, both without and with the extract at concentrations of 0.5, 1.0, and 1.5 g/L. Morphology and composition of steel samples after 24 h in blank and inhibited solutions, examined by SEM and EDX, revealed the inhibitive effect of dandelion extract, since corrosion products were not visible on the steel surfaces after 24 h in the inhibited solution, unlike the blank steel surfaces. Based on the weight loss, dandelion extract inhibited corrosion processes of S2 in a chloride-rich environment at all examined concentrations; on the other hand, it acted as a corrosion inhibitor of S1 in 3% NaCl only at the concentrations of 1.0 and 1.5 g/L. According to corrosion current, corrosion potential and polarization resistance determined by potentiodynamic tests, dandelion root extract is a mixed corrosion inhibitor with a dominant anodic reaction, which decreases corrosion rate by adsorbing onto anodic sites and prevents steel dissolution. According to ATR-FTIR analysis, hydroxyl groups within the inulin molecule could act as the dominant metal-complexing groups. Therefore, the adsorption properties of dandelion root extract are most probably related to this specific site. Based on electrochemical impedance spectroscopy, the enhancement of corrosion resistance in the steel samples was evident in all the inhibited solutions examined compared to a pure 3% NaCl solution.